A RAPID RESPONSE ASSESSMENT

BLUE CARBON
THE ROLE OF HEALTHY OCEANS IN BINDING CARBON

1This report is produced as an inter-agency collaboration between UNEP, FAO and IOC/UNESCO, with special invited contribution of Dr. Carlos M. Duarte, Institut Mediterráni d’Estudis Avançats, Spain.

Nellemann, C., Corcoran, E., Duarte, C. M., Valdés, L., De Young, C.,
Fonseca, L., Grimsditch, G. (Eds). 2009. Blue Carbon. A Rapid Response
Assessment. United Nations Environment Programme, GRID-Arendal,
www.grida.no
ISBN: 978-82-7701-060-1
Printed by Birkeland Trykkeri AS, Norway
Disclaimer
The contents of this report do not necessarily reflect the views or policies of UNEP or contributory organisations. The designations employed and the presentations do not imply theexpressions of any opinion whatsoever on the part of UNEP or contributory organisations
concerning the legal status of any country, territory, city, company or area or its authority, orconcerning the delimitation of its frontiers or boundaries.

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BLUE CARBON
THE ROLE OF HEALTHY OCEANS IN BINDING CARBONA RAPID RESPONSE ASSESSMENT

Christian Nellemann (Editor in chief)
Emily Corcoran
Carlos M. Duarte
Luis Valdés
Cassandra De Young
Luciano Fonseca
Gabriel Grimsditch

4

PREFACE

The most crucial, climatecombating coastal ecosystems
are disappearing faster thananything on land and much may
be lost in a couple of decades.

If the world is to decisively deal with climate change, every source of emissions and every
option for reducing these should be scientifically evaluated and brought to the interna­
tional community’s attention.
The burning of fossil fuels is generating levels of what one
might term ‘brown’ and ‘black’ carbon in the atmosphere andunless checked may take global temperatures above a thresholdof 2˚C. Dramatic reductions are possible by accelerating energy
efficiency measures and boosting the deployment of cleaner
energy generation and renewables such as solar, wind and geothermal. Over the past few years science has been illuminatingother sources of emissions and other opportunities for action.
Deforestation for example now accounts for close to 20% of
global greenhouse gas emissions.
In a matter of weeks, governments will meet in Copenhagen
where there is an urgency to Seal the Deal on a new and forwardlooking agreement. Part of that package of measures needs toinclude ‘green’ carbon – the carbon stored in the globe’s forests
and their soils and especially in the tropics. Financing a partnership for Reduced Emissions from Deforestation and forest
Degradation (REDD) can play an important role in keeping thatgreen carbon where it belongs while also assisting the development and employment objectives of developing economies bygiving an economic value to these vital ecosystem services.
Science is now also telling us that we need to urgently address
the question of ‘blue’ carbon. An estimated 50% of the carbon in
the atmosphere that becomes bound or ‘sequestered’ in natural
systems is cycled into the seas and oceans – another example ofnature’s ingenuity for ‘carbon capture and storage’. However, aswith forests we are rapidly turning that blue carbon into browncarbon by clearing and damaging the very marine ecosystems
that are absorbing and storing greenhouse gases in the first place.

This in turn will accelerate climate change, putting at risk communities including coastal ones along with other economicallyimportant assets such as coral reefs; freshwater systems andmarine biodiversity as well as ‘hard’ infrastructure from ports
to power-stations. Targeted investments in the sustainable
management of coastal and marine ecosystems – the natural
infrastructure – alongside the rehabilitation and restoration ofdamaged and degraded ones, could prove a very wise transaction with inordinate returns.
This report, produced by some of the world’s leading scientists
and in collaboration with the FAO and IOC-UNESCO, findsthat the most crucial, climate-combating coastal ecosystems
cover less than 0.5% of the sea bed. But they are disappearing
faster than anything on land and much may be lost in a coupleof decades. These areas, covering features such as mangroves,
salt marshes and seagrasses, are responsible for capturing andstoring up to some 70% of the carbon permanenty stored in themarine realm.
If we are to tackle climate change and make a transition to a resource efficient, Green Economy, we need to recognize the roleand the contribution of all the colours of carbon. Blue carbon,
found and stored away in the seas and oceans, is emerging as
yet another option on the palette of promising opportunities
and actions, one that can assist in delivering a bright rather
than a dark brown and ultimately black future.
Achim Steiner
UN Under-Secretary General and Executive Director, UNEP
5

EXECUTIVE SUMMARY

The objective of this report is to highlight the critical role of the oceans and ocean ecosys­
tems in maintaining our climate and in assisting policy makers to mainstream an oceans
agenda into national and international climate change initiatives. While emissions’ re­ductions are currently at the centre of the climate change discussions, the critical role ofthe oceans and ocean ecosystems has been vastly overlooked.
Out of all the biological carbon (or green carbon) captured in
the world, over half (55%) is captured by marine living organisms – not on land – hence it is called blue carbon. Continually increasing carbon dioxide (CO2) and other greenhouse gas
emissions are contributing to climate change. Many countries,
including those going through periods of rapid growth, areincreasing their emissions of brown and black carbon (suchas CO2 and soot) as a result of rapid economic development.
Along with increased emissions, natural ecosystems are being
degraded, reducing their ability to absorb CO2. This loss of capacity is equivalent to one to two times that of the annual emissions from the entire global transport sector.
Rising greenhouse gases emissions are producing increasing
impacts and changes worldwide on weather patterns, food production, human lives and livelihoods. Food security, social, economic and human development will all become increasingly
jeopardized in the coming decades.
Maintaining or improving the ability of forests and oceans
to absorb and bury CO2 is a crucial aspect of climate change
mitigation. The contribution of forests in sequestering carbon
is well known and is supported by relevant financial mechanisms. In contrast, the critical role of the oceans has been overlooked. The aim of this report is to highlight the vital contribution of the oceans in reducing atmospheric CO2 levels through6

sequestration and also through reducing the rate of marine andcoastal ecosystem degradation. It also explores the options fordeveloping a financial structure for managing the contribution
oceans make to reducing CO2 levels, including the effectiveness of an ocean based CO2 reduction scheme.
Oceans play a significant role in the global carbon cycle. Not
only do they represent the largest long-term sink for carbon but
they also store and redistribute CO2. Some 93% of the earth’s
CO2 (40 Tt) is stored and cycled through the oceans.
The ocean’s vegetated habitats, in particular mangroves, salt
marshes and seagrasses, cover <0.5% of the sea bed. These
form earth’s blue carbon sinks and account for more than
50%, perhaps as much as 71%, of all carbon storage in ocean
sediments. They comprise only 0.05% of the plant biomass onland, but store a comparable amount of carbon per year, andthus rank among the most intense carbon sinks on the planet.
Blue carbon sinks and estuaries capture and store between
235–450 Tg C every year – or the equivalent of up to half ofthe emissions from the entire global transport sector, estimatedat around 1,000 Tg C yr–1. By preventing the further loss anddegradation of these ecosystems and catalyzing their recovery,
we can contribute to offsetting 3–7% of current fossil fuel emissions (totaling 7,200 Tg C yr–1) in two decades – over half ofthat projected for reducing rainforest deforestation. The effectwould be equivalent to at least 10% of the reductions needed tokeep concentrations of CO2 in the atmosphere below 450 ppm.
If managed properly, blue carbon sinks, therefore, have the potential to play an important role in mitigating climate change.
The rate of loss of these marine ecosystems is much higher
than any other ecosystem on the planet – in some instances
up to four times that of rainforests. Currently, on average, between 2–7% of our blue carbon sinks are lost annually, a seven-fold increase compared to only half a century ago. If moreaction is not taken to sustain these vital ecosystems, most may
be lost within two decades. Halting degradation and restoring
both the lost marine carbon sinks in the oceans and slowing
deforestation of the tropical forests on land could result in
mitigating emissions by up to 25%.
Sustaining blue carbon sinks will be crucial for ecosystembased adaptation strategies that reduce vulnerability of human coastal communities to climate change. Halting the decline of ocean and coastal ecosystems would also generate
economic revenue, food security and improve livelihoods inthe coastal zone. It would also provide major economic anddevelopment opportunities for coastal communities aroundthe world, including extremely vulnerable Small Island Developing States (SIDS).
Coastal waters account for just 7% of the total area of theocean. However the productivity of ecosystems such as coral
reefs, and these blue carbon sinks mean that this small area
forms the basis of the world’s primary fishing grounds, supplying an estimated 50% of the world’s fisheries. They provide
vital nutrition for close to 3 billion people, as well as 50% ofanimal protein and minerals to 400 million people of the least
developed countries in the world.

The coastal zones, of which these blue carbon sinks are central for productivity, deliver a wide range of benefits to human society: filtering water, reducing effects of coastal pollution, nutrient loading, sedimentation, protecting the coastfrom erosion and buffering the effects of extreme weather
events. Coastal ecosystem services have been estimated to be
worth over US$25,000 billion annually, ranking among themost economically valuable of all ecosystems. Much of thedegradation of these ecosystems not only comes from unsustainable natural resource use practices, but also from poor
watershed management, poor coastal development practices
and poor waste management. The protection and restorationof coastal zones, through coordinated integrated management would also have significant and multiple benefits forhealth, labour productivity and food security of communities
in these areas.
The loss of these carbon sinks, and their crucial role in managing climate, health, food security and economic development in the coastal zones, is therefore an imminent threat.
It is one of the biggest current gaps to address under climatechange mitigation efforts. Ecosystem based management
and adaptation options that can both reduce and mitigate
climate change, increase food security, benefit health andsubsequent productivity and generate jobs and business areof major importance. This is contrary to the perception thatmitigation and emission reduction is seen as a cost and not
an investment. Improved integrated management of thecoastal and marine environments, including protection andrestoration of our ocean’s blue carbon sinks, provides one of
the strongest win-win mitigation efforts known today, as it
may provide value-added benefits well in excess of its costs,
but has not yet been recognized in the global protocols andcarbon trading systems
7

KEY OPTIONS:In order to implement a process and manage the necessary funds for the protection,
management and restoration of these crucial ocean carbon sinks, the following options
are proposed:

Establish a global blue carbon fund for protection
and management of coastal and marine ecosystems and ocean carbon sequestration.
a. Within international climate change policy instruments, create mechanisms to allow the future use of carbon credits formarine and coastal ecosystem carbon capture and effective storage as acceptable metrics become available. Blue carbon could
be traded and handled in a similar way to green carbon – suchas rainforests – and entered into emission and climate mitigation protocols along with other carbon-binding ecosystems;
b. Establish baselines and metrics for future environmentallysound ocean carbon capture and sequestration;c. Consider the establishment of enhanced coordination andfunding mechanisms;
d. Upscale and prioritize sustainable, integrated and ecosystem-based coastal zone planning and management, especiallyin hotspots within the vicinity of blue carbon sinks to increase
the resilience of these natural systems and maintain food andlivelihood security from the oceans.

1

Immediately and urgently protect at least 80% of
remaining seagrass meadows, salt marshes andmangrove forests, through effective management.
Future funds for carbon sequestration can contribute to maintaining management and enforcement.

2

8

3

Initiate management practices that reduce and remove threats, and which support the robust recovery
potential inherent in blue carbon sink communities.

Maintain food and livelihood security from theoceans by implementing comprehensive and integrated ecosystem approaches aiming to increase
the resilience of human and natural systems to change.

4

Implement win-win mitigation strategies in theocean-based sectors, including to:a. Improve energy efficiency in marine transport, fishing and aquaculture sectors as well as marine-based tourism;
b. Encourage sustainable, environmentally sound ocean basedenergy production, including algae and seaweed;c. Curtail activities that negatively impact the ocean’s ability toabsorb carbon;
d. Ensure that investment for restoring and protecting the capacity of ocean’s blue carbon sinks to bind carbon and provide
food and incomes is prioritized in a manner that also promotes
business, jobs and coastal development opportunities;
e. Catalyze the natural capacity of blue carbon sinks to regenerate by managing coastal ecosystems for conditions conducive
to rapid growth and expansion of seagrass, mangroves, and salt
marshes.

5

CONTENTS
5
6

PREFACEEXECUTIVE SUMMARY11

INTRODUCTION

15EMISSIONS AND SEQUESTRATION– THE BINDING OF CARBON

23

BLUE PLANET: OCEANS AND CLIMATE

35

BLUE CARBON – THE ROLE OF OCEANS
AS CARBON SINKS

45

THE WORLD’S OCEAN CARBON SINKSIN RAPID DECLINE

51

OCEANS’ BLUE CARBON SINKS AND
HUMAN WELLBEING61

ECOSYSTEM BASED ADAPTATION AND
MITIGATION

65

POLICY OPTIONS

70
72
73
74

GLOSSARY
ACRONYMSCONTRIBUTORSREFERENCES

910

INTRODUCTION
Of all the Green carbon captured annually in the world, that is the carbon captured byphotosynthetic activity, over half (55%) is captured by marine living organisms (Falkow­
ski et al., 2004; Arrigo, 2005; González, et al., 2008; Bowler, 2009; Simon et al., 2009).
This oceanic carbon cycle is dominated by micro-, nano-, and picoplankton, including
bacteria and archaea (Burkill, 2002). Even though plant biomass in the oceans is only
a fraction of that on land, just 0.05%, it cycles almost the same amount of carbon eachyear (Bouillon et al., 2008; Houghton, 2007); therefore representing extremely efficientcarbon sinks. However, while increasing efforts are being made to slow degradation onland, such as through protection of rainforests as a means to mitigate climate change, therole of marine ecosystems has to date been largely ignored.

Knowledge of the role of natural ecosystems in capturing CO2
is an increasingly important component in developing strategies to mitigate climate change. Losses and degradation ofnatural ecosystems comprise at least 20–30% of our total emissions (UNEP, 2008a; 2009). While overall emissions from theburning of fossil fuels needs to be severely reduced, mitigatingclimate change can also be achieved by protecting and restoring
natural ecosystems (Trumper et al., 2009). Even from a narrow perspective of emission reductions alone, they can play asignificant role. As steep reduction of fossil fuel emissions may
compromise the development potential of some countries, it iscritical that options are identified that can help mitigate climatechange with neutral or even positive impacts on development.
It is therefore absolutely critical to identify those natural ecosystems that contribute most to binding our increasing emissionsof carbon or CO2 and enhance this natural capacity (Trumper etal., 2009). Some of these are in the oceans.
Some 93% of the earth’s carbon dioxide – 40Tt CO2 – is stored
in the oceans. In addition, oceans cycle about 90 Gt of CO2 yr–1

(González et al., 2008), and remove over 30% of the carbon
released to the atmosphere.
Resilient aquatic ecosystems not only play a crucial role in binding carbon, they are also important to economic development,
food security, social wellbeing and provide important buffers
against pollution, and extreme weather events. Coastal zones
are of particular importance, with obvious relations and importance to fisheries, aquaculture, livelihoods and settlements (Kayand Alder, 2005) – over 60% of the world’s population is settled
in the coastal zone (UNEP, 2006, 2008b). For many coastal
developing countries, the coastal zone is not only crucial for
the wellbeing of their populations, it could also, as documented
in this report, provide a highly valuable global resource for climate change mitigation if supported adequately.
This report explores the potential for mitigating the impactsof climate change by improved management and protection ofmarine ecosystems and especially the vegetated coastal habitat,or blue carbon sinks.
11

1 020Atmosphere

750

121

92

60

Land use change

8

0.5

60

90
610

1.5
Rivers

Biosphere
-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

--

-

-

-

-

- -

-

-

-

-

-

-

-

-

-

- Soil

-

-

-

-

-

-

-

-

-

1 580

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

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-

-

0.8

-

-

-

-

-

96.1
-

-

-

- - - - - - - - - - - - - - - - - - - - - - - - Oil
and
gas
300
fields 3000- -- Coal fields - - - - - - - -Carbon fluxes and stocks
- -

-

-

-

-

-

- -

1 020

8

-

-

Storage:- Gigatonnes of C -Fluxes: Gigatonnes of C per year

Source: IPCC.
12

-

- -

-

-

-

- -

-

-

-

-

-

-

-

-

-

-

-

-

-

Carbon cycle

Ocean surface
1 020

Definition: Measuring Carbon

50
Dissolved organic C
40-- - -- - --3 - --

650

650
Labiledissolved
organic C

Marine
biota

4
100

6

Units of Carbon used. This report will use Tg C, but readers will also see values for C and CO2, provided in a wide
range of formats. The following information may assist
in wider reading.
Name

FactorSymbolOne thousand
One million
One billion
One trillion

103
106
109
1012
1015

k (Kilo)M (Mega)
G (Giga)
T (Tera)P (Peta)

1km2 = 100ha
1 ton = 2,240lbs
1 (metric) ton = 1,000kg or 1x106g
Blue carbon sinks capture CO2 through photosynthesis
from the air and water and store it as carbon.

Deep ocean

The rate of converting C to CO2 is 44/12; i.e. 1 aton of C
is equivalent to 3.67t CO2

38 1000.2

 Figure 1: Carbon Cycle. Oceans are crucial in the global
150

Sediments

carbon cycle. It was here where life first evolved; they are
the source of our wealth and development. The living
oceans capture over half of all the Green carbon – the carbon bound by living organisms through photosynthesis.

13

14

EMISSIONS AND SEQUESTRATION– THE BINDING OF CARBON
Anthropogenic climate change is caused by the rising content of greenhouse gases andparticles in the atmosphere. Firstly by the burning of fossil fuels, releasing greenhousegases such as CO2, (“brown carbon”) and dust particles (part of “black carbon”); secondly
by emissions from clearing natural vegetation, forest fires and agricultural emissions, in­cluding those from livestock; and thirdly – by the reduced ability of natural ecosystems tobind carbon through photosynthesis and store it – so called green carbon (Trumper et al.,2009). The uptake of CO2 into a reservoir over long (several decades or centuries) timescales, whether natural or artificial is called carbon sequestration (Trumper et al., 2009).
Fact box 1. The colours of carbon: Brown, Black, Blue and Green
Climate Change has driven widespread appreciation of atmospheric CO2 as the main greenhouse gas and of the role of anthropogenic CO2 emissions from energy use and industry inaffecting temperatures and the climate – we refer to these emissions as “brown carbon” for greenhouse gases and “black carbon” for particles resulting from impure combustion, such assoot and dust. The Emissions Trading System of the European
Union (EU-ETS) is a “black-brown carbon” system as it does notincorporate forestry credits. The Kyoto Protocol’s Clean Development Mechanism (CDM) does in principle include forestry
credits, but demand (in the absence of a linking directive anddemand from the EU-ETS) and prices have always been too low
to encourage success, so CDM has also become, for all practical
purposes, another “black carbon” mechanism.
Terrestrial carbon stored in plant biomass and soils in forest land,
plantations, agricultural land and pasture land is often called “green
carbon”. The importance of “green carbon” is being recognizedthrough anticipated agreement at the United Nations Framework
Convention on Climate Change Conference of the Parties (COP)in Copenhagen, December 2009, which includes forest carbon– through various mechanisms, be they REDD and afforestation,
REDD-Plus, and/or others (e.g. ‘Forest Carbon for Mitigation’). The

world’s oceans bind an estimated 55% of all carbon in living organisms. The ocean’s blue carbon sinks – particularly mangroves,
marshes and seagrasses capture and store most of the carbon
buried in marine sediments. This is called “blue carbon”. These
ecosystems, however, are being degraded and disappear at rates
5–10 times faster than rainforests. Together, by halting degradationof “green” and “blue” carbon binding ecosystems, they represent
an emission reduction equivalent to 1–2 times that of the entire
global transport sector – or at least 25% of the total global carbon
emission reductions needed, with additional benefits for biodiversity, food security and livelihoods. It is becoming increasingly clearthat an effective regime to control emissions must control the entire “spectrum” of carbon, not just one “colour”.
In the absence of “Green Carbon”, biofuel cropping can become
incentivized, and can lead to carbon emissions if it is not done correctly. The conversion of forests, peatlands, savannas and grasslands to produce food-crop based biofuels in Brazil, Southeast Asiaand the United States creates a biofuel carbon debt by emitting 14
to 420 times more CO2 than the annual reductions in greenhousegases these biofuels provide by replacing fossil fuels. In contrast,
biofuels produced from waste biomass and crops grown on degraded agricultural land do not accrue any such carbon debt.
15

BROWN, BLACK, GREEN AND BLUE CARBON
Brown and black carbon emissions from fossil fuels, biofuels
and wood burning are major contributors to global warming.
Black carbon emissions have a large effect on radiation transmission in the troposphere, both directly and indirectly via
clouds, and also reduce the snow and ice albedo.
Black carbon is thought to be the second largest contributor to
global warming, next to brown carbon (the gases). Thus, reducing black carbon emission represents one of the most efficient
ways for mitigating global warming that we know today.
Black carbon enters the ocean through aerosol and river deposition. Black carbon can comprise up to 30% of the sedimentaryorganic carbon (SOC) in some areas of the deep sea (Masielloand Druffel, 1998) and may be responsible for 25% of observed

Actual and projected energy demand

Projections

Oil

12

9

Coal

6

Gas
3

0
1980

NuclearHydropower

Biomass

GREEN CARBON

Green carbon is carbon removed by photosynthesis and stored
in the plants and soil of natural ecosystems and is a vital part of
the global carbon cycle. Sofar, however, it has mainly been considered in the climate debate in terrestrial ecosystems, though
the issue of marine carbon sequestration has been known for
at least 30 years.

Unlike many plants and most crops, which have short lives orrelease much of their carbon at the end of each season, forest biomass accumulates carbon over decades and centuries. Furthermore, forests can accumulate large amounts of CO2 in relatively
short periods, typically several decades. Afforestation and reforestation are measures that can be taken to enhance biological carbon sequestration. The IPCC calculated that a global programme
involving reduced deforestation, enhanced natural regenerationof tropical forests and worldwide re-afforestation could seques-

Other
renewables
1990

2000

2010

2020

2030

Note: All statistics refer to energy in its original form (such as coal) before beingtransformed into more convenient energy (such as electrical energy).
Source: International Energy Agency (IEA), World Energy Outlook 2008.

Figure 2: Projected growth in energy demand in coming decades.
16

The total CO2 emissions of are estimated to be between 7,200
Tg C yr–1, and 10,000 Tg C yr–1 (Trumper et al., 2009), andthe amount of carbon in the atmosphere is increasing by approximately 2,000 Tg C yr–1 (Houghton, 2007).

A sink is any process, activity or mechanism that removes agreenhouse gas, an aerosol or a precursor of a greenhouse gas
or aerosol from the atmosphere. Natural sinks for CO2 are forexample forests, soils and oceans.

Gigatonnes of oil equivalent

15

global warming over the past century. Black carbon tends toremain in the atmosphere for days-weeks (Hansen and Nazarento, 2004) whereas CO2 remains in the atmosphere for approx 100 years (IGSD, 2009).

 Figure 3: World greenhouse emission by sector. All transport
accounts for approximately 13.5% of the total emissions, while
deforestation accounts for approximately 18%. However, estimates of the loss of marine carbon-binding ecosystems havepreviously not been included.

World greenhouse gas emissions by sector
SectorTransportation

End use/activity
13.5%

Road

Gas
9.9%

Residential buildings

9,9%Commercial buildings

5.4%

Electricity & heat

24.6%

N
E

Unallocatedfuel combustion
Iron & steel

3.5%
3.2%
Aluminium/Non-ferrous metals 1.4%

E

R

G

Y

Air
1.6%
Rail, ship & other transport 2.3%

Other fuelcombustion1%
Machinery
Pulp, paper & printing
1%

Food & tobacco

Chemicals

1%
4.8%

Cement3,8%Other industry

5,0%

T&D losses
Coal mining

1,9%
1,4%

Fugitive emissions 3.9%
Industrial processes 3.4%

Oil/gas extraction,
Refining & processing

6.3%

Land use change

Deforestation
Afforestation
Reforestation
Harvest/Management
Other

18.3%
-1.5%
-0.5%
2.5%
-0.6%

Industry

Agriculture
Waste

9%

10.4%

18.2%

13.5%
3.6%

Agricultural energy use

1.4%

Agriculture soils

6%

Livestock & manure

5.1%

Rice cultivation
Other agriculture
Landfills
Wastewater, other waste

1.5%
0.9%
2%
1.6%

Carbon dioxide
(CO2)

77%

HFCs,
PFCs,
SF6
1%

Methane(CH4) 14%
Nitrous oxide(N2O) 8%All data is for 2000. All calculations are based on CO2 equivalents, using 100-year global warming potentials from the IPCC
(1996), based on a total global estimate of 41 755 MtCO2 equivalent. Land use change includes both emissions and absorptions.
Dotted lines represent flows of less than 0.1% percent of total GHG emissions.
Source: World Resources Institute, Climate Analysis Indicator Tool (CAIT), Navigating the Numbers: Greenhouse Gas Data andInternational Climate Policy, December 2005; Intergovernmental Panel on Climate Change, 1996 (data for 2000).

17

Black Carbon emissions
Share by sector and geographic
distribution

East Asia
Western Africa

South America

Southern Asia
South-East Asia
Southern Africa
East Africa
USA

Central America

Former USSR

OceaniaJapan

East Europe
Middle East

CanadaNorthern Africa
6%

Residential - coal and others

10%

Industry and power generation

10%

Transport - non road

14%

Transport - road

18%

Residential - biofuel

42%

Open biomass

ter 60–87 Gt of atmospheric carbon by 2050, equivalent
to some 12–15% of projected CO2 emissions from fossil
fuel burning for that period (Trumper et al., 2009).
It is becoming better understood that there are criticalthresholds of anthropogenic climate change, beyond
which dangerous thresholds will be passed (IPCC,
2007a). For example, to keep average temperature rises
to less than 2°C, global emissions have to be reduced
by up to 85% from 2000 levels by 2050 and to peakno later than 2015, according to the IPCC (Trumper etal., 2009).

Black Carbon emissions
Teragrams per year (2000)
1570
800
380
200
120
Sources: Bond et al., 2000.

18

But while the loss of green carbon ecosystems have attracted much interest, for example by combating the Figure 4: Combustion sources of black carbon.
(Source: Dennis Clare, State of the World 2009, www.
worldwatch.org).

Green Carbon

Tropical,
Subtropical,
Savannas,
Shrublands
Temperate
ForestBorealForestDeserts and
Dry Shrubland

Temperate
Grasslands,
Savannas
Shrublands

Tropical,
Subtropical
Forests
TundraGigatonnesof C stored interrestrial
biomes
547.8

loss of tropical rainforests, the fact that near 55% of all
green carbon is captured by living organisms not on land,but in oceans, has been widely ignored, possibly our greatest deficit in mitigating climate change. The carbon captured by marine organisms is herein called “blue carbon”.

285.3

178.0

BLUE CARBON

Blue carbon is the carbon captured by the world’s oceans
and represents more than 55% of the green carbon. The
carbon captured by living organisms in oceans is stored in
the form of sediments from mangroves, salt marshes andseagrasses. It does not remain stored for decades or centuries (like for example rainforests), but rather for millennia.
In this report, the prospects and opportunities of binding
carbon in oceans is explored.

183.7

Tonnes of C stored per hectare

314.9

325

130

384.2

50

 Figure 5: 45% of green carbon stored in natural terrestrial

ecosystems and the remaining 55% is captured by living organisms in oceans by plankton and ocean’s blue carbon sinks.

Source: UNEP-WCMC, 2009.

155.4

19

20

21

Look again at that dot.
That’s here. That’s home. That’s us.
On it everyone you love, everyone you know, everyone
you ever heard of, every human being who ever was,lived out their lives. The aggregate of our joy andsuffering, thousands of confident religions, ideologies,
and economic doctrines, every hunter and forager,
every hero and coward, every creator and destroyer ofcivilization, every king and peasant, every young couple
in love, every mother and father, hopeful child, inventor
and explorer, every teacher of morals, every corrupt
politician, every ‘superstar’, every ‘supreme leader,’every saint and sinner in the history of our species lived
there – on a mote of dust suspended in a sunbeam.
Carl Sagan 1997.
Image from the solar system taken by the Voyager 1 spacecraft (NASA/JPL).
22

BLUE PLANET:OCEANS AND CLIMATEThe existence of the vast ocean is the main defining characteristic of our planet, mak­ing earth unique in the solar system and the only Blue Planet. Although water is notuncommon in the universe, oceans are probably extremely rare. Other planets in the so­lar system have evidence of ice, ancient water
How inappropriate to call this planet earthbasins and valleys, or even subsurface liquid
when it is quite clearly Ocean.
water, but planet earth is the only one which
Arthur C. Clarke
has liquid surface water; probably due to our
privileged position in respect to the sun: not close enough to evaporate and escape, nor
far enough to freeze. Water is also linked to the origin of life, in which early organic
molecules rested protected from temperature swings and from the sun’s destructive
ultraviolet radiation, and where they could move freely to combine and evolve. This
successful combination of water and life changed the composition of the atmosphereby releasing oxygen and extra water vapour, and shaped our landscape, through ero­sion, weathering and sedimentation, in a continuous interchange of water between theocean, the land and the atmosphere.

Water moves in a continuous cycle that begins and ends inthe ocean. This hydrologic cycle is powered by solar radiation,
which provides energy for evaporation. Then precipitation,transpiration from plants, runoff into streams and infiltration
to ground water reservoirs complete the cycle, which will startover again when most of the initial evaporated water reaches
the ocean. Although during the cycle, water can be present indifferent states as ice, liquid or vapor, the total water content
of the ocean has remained fairly constant since its formation,with an average residence time of approximately 3,000 years.
At the moment, 97.25% of the water in planet earth is in theform of liquid salty water in the oceans, with only 2.05%
forming ice covers and glaciers, 0.68% groundwater, 0.01%

rivers and lakes, and 0.001% in the atmosphere (Campy and
MaCaire, 2003).
Oceans have been influencing the climate and the ecology ofthe planet since the very beginning of life on earth. Over time,
both the physical oceans and living organisms have contributed to the cycling of carbon. Plankton in marine ecosystems
produces more organic material than is needed to maintainthe food chain. The excess carbon slowly accumulates on thesea bed during geological time (biological pump) (Longhurst,
1991; Siegenthaler and Sarmiento, 1993; Raven and Falkowski,1999). With that process, sediment and fossilized carbonate
plankton have changed the shape of our coasts.
23

ATMOSPHERIC CIRCULATION PATTERNS

Low
Latitudes

CO2

PHYSICAL PUMPTransport of CO2
by Vertical
Mixing and Deep
Water Masses

Vertical Mixing
Local Action
Short-time
Scale

CO2

SOLUBILITY PUMPTransport of CO2
through the
air-sea interface

CO2

CO2

CO2

CO2
AIR-SEA INTERFACE CO2 EXCHANGESHigh
Latitudes

CO2
Deep Water Masses
Formation
Global Action
Long-time
Scale
Nutrients(Ammonia)

Respiration
Food Web

Phytoplankton
CO2
Nutrients

Primary
Production

OxygenOrganic Carbon

tsen )tri ateNu Nitr(

Egestion
Decomposition

CO2
Bacteria
Remineralization

Particulate Carbon(Organic and Inorganic)
Sinking

Carbon Deposition

BIOLOGICAL PUMP
Vertical gravitational
settlings ofbiogenic debris
Carbon Burial

24

CO2

CO2

nts
trieate)
u
N itr
(N

Bacteria
Oxidation
Sources:
R. Chester, 2003; H. Elderfield, 2006; R.A. Houghton, 2007; T.J.
Lueker et al, 2000;J.A. Raven and P.G. Falkowski, 1999.

 Figure 6: Carbon cycling in the world’s oceans. The
flow of carbon dioxide across the air-sea interface isa function of CO2 solubility in sea water (Solubility
Pump). The amount of CO2 dissolved in sea water
is mainly influenced by physico-chemical conditions(sea water temperature, salinity, total alkalinity) andbiological processes, e.g. primary production. The
solubility pump and the biological pump enhance theuptake of CO2 by the surface ocean influencing its values for dissolved CO2 and transferring carbon to deep
waters. All these mechanisms are strongly connected,
subtly balanced and influential to the ocean’s capacity
to sink carbon. The net effect of the biological pumpin itself is to keep the atmosphere concentration of
CO2 around 30% of what it would be in its absence(Siegenthaler and Sarmiento, 1993).

Oceans are absorbing both heat and carbon from the atmosphere,
therefore alleviating the impacts of global warming in the environment. Covering more than two-thirds of the earth’s surface, theoceans store the sun’s energy that reaches earth’s surface in theform of heat, redistribute it, from the coast to the mid-ocean, shallow to deep waters, polar to tropical, and then slowly release it backto the atmosphere. These storage and circulation processes prevent
abrupt changes in temperature, making coastal weather mild andsome high latitude areas of the globe habitable. However this hugeheat storage capacity can have undesirable consequences with theadvent of climate change. With global warming, the ocean is absorbing a large portion of the excess heat present in the atmosphere(almost 90%), resulting in a measurable increase of surface watertemperatures (an average of approximately 0.64oC over the last 50
years) (Levitus et al., 2000; IPCC, 2007b). As water warms, it ex-

Oceans carbon fluxes

Mol of carbon per square metre
Net carbon
release

1
0.5
-0.5
-1
Net carbon
uptakeSource: Marine Institute, Ireland, 2009.

Figure 7: Carbon fluxes in the oceans. (Source: adapted from Takahashi et al., 2009).
25

Thermohaline circulation
Deep water formation
Deep water formation

Pacific
Ocean

Surfacecurrent
Deep current

Pacific
Ocean

Practical salinity unit
31 34 36 39

IndianOcean

Atlantic
Ocean

Deep water formation(1 psu = 1 gram of salt per kilogram of water)

Source : NASA, 2009.

Figure 8: Thermohaline circulation is a 3-dimensional flow involving surface and deep ocean waters, which
is driven by differences in water temperature and salinity. (Image source: NOAA/NCDC).
pands causing the ocean surface to rise (UNEP, 2008b). Overtime, this heat will descend to greater ocean depths, increasing
expansion and triggering further changes in sea level.
Melting of sea ice in the Arctic, inland glaciers and continental ice sheets of Greenland and Antarctica is changing the salinity of sea water and in some cases also contributing to sea
level rise (UNEP, 2008b). So, melting and warming will havefurther consequences on ocean circulation, as ocean currents
are driven by the interactions between water masses through abalance with temperature and salinity, which controls the density. Changes in oceanic currents could expose local climatesto abrupt changes in temperature. Higher water temperatures
also lead to increased evaporation, making more energy available for the atmosphere. This has direct consequences on
26

extreme weather events, as warming sea temperatures boost
the destructive energy of hurricanes, typhoons, etc. Tropicalsea-surface temperatures have warmed by only half a degree
Celsius, while a 40% increase in the energy of hurricanes has
been observed (Saunders and Lea, 2008).
Warmer, low salinity surface waters together with the annual seasonal heating are extending and strengthening the seasonal layers in the water-column (stratification), limiting the vertical movement of water masses. This phenomenon together with changes
in wind regimes has implications for some of the most productive parts of earth’s oceans (Le Quéré et al., 2007), where upwelling of deep waters and nutrients enhances primary production,
supporting massively abundant surface ecosystems. If reductionof upwelling occurs to any degree, marine ecosystems, fisheries

and communities will be negatively affected. It is important tohighlight that enhanced stratification is already a fact in temperate seas at mid-latitudes, where stratification is diminishing thetotal annual primary production as a result of the reduction in the
supply of nutrients to the surface layers (Cushing, 1989; Valdésand Moral, 1998; Valdés et al., 2007). Warming temperatures arealso changing the geographical ranges of marine species. Changes in depth range are occurring, as species shift down in thewater column to escape from warming surface waters. There isalso evidence that the distribution of zooplankton, fish and othermarine fauna has shifted hundreds of kilometers towards higher
latitudes, especially in the North Atlantic, the Arctic Ocean, andthe Southwest Pacific Ocean (Cheung et al., 2009)

ning of the industrial era (Sabine and Feely, 2007). In so doing,
the ocean acted as a buffer for earth’s climate, as this absorptionof CO2 mitigates the effect of global warming by reducing its
concentration in the atmosphere. However, this continual intake
of CO2 and heat is changing the ocean in ways that will havepotentially dangerous consequences for marine ecology and biodiversity. Dissolved CO2 in sea water lowers the oceans’ pH level,causing acidification, and changing the biogeochemical carbonate balance (Gattuso and Buddemeier, 2000; Pörtner et al.,2004). Levels of pH have declined at an unprecedented rate insurface sea water over the last 25 years and will undergo a further
substantial reduction by the end of this century as anthropogenic
sources of CO2 continue to increase (Feely et al., 2004).

Another important role played by the ocean is the storage andexchange of CO2 with the atmosphere, and its diffusion toward
deeper layers (solubility pump) (Fact box 2) (Siegenthaler andSarmiento, 1993). The ocean has absorbed approximately onethird of the total anthropogenic CO2 emissions since the begin-

As the ocean continues to absorb further heat and CO2, its ability
to buffer changes to the atmosphere decreases, so that atmosphereand terrestrial ecosystems will face the full consequences of climate change. At high latitudes, dense waters sink, transferring
carbon to the deep ocean. Warming of the ocean surface inhibits
this sinking process and therefore reduces the efficiency of CO2transport and storage. Furthermore, as water warms up, the solubility of CO2 declines, therefore less gas can be stored in the sea
water. With acidification, warming, reduced circulation and mixing, there has been a significant change in plankton productivity
in the ocean, reducing the portion of the carbon budget that would
be carried down to the deep seafloor and stored in sediments.

Fact box 2. The ocean – a giant carbon pump
The solubility pump: CO2 is soluble in water. Through a gasexchange process CO2 is transferred from the air to the ocean,
where it forms of dissolved inorganic carbon (DIC). This is acontinuous process, as sea water is under-saturated with CO2
compared to the atmosphere. The CO2 is subsequently distributed by mixing and ocean currents. The process is more efficient at higher latitudes as the uptake of CO2 as DIC increases
at lower temperatures since the solubility of CO2 is higher incold water. By this process, large quantities of CO2 are removed
from the atmosphere and stored where they cannot contribute
immediately to the greenhouse effect.
The biological pump: CO2 is used by phytoplankton to grow.
The excess of primary production sinks from the ocean surface to the deep sea. In the very long term, part of this carbon
is stored in sediments and rocks and trapped for periods of
decades to centuries. In order to predict future CO2 concentrations in the atmosphere, it is necessary to understand the waythat the biological pump varies both geographically and temporally. Changes in temperature, acidification, nutrient availability, circulation, and mixing all have the potential to changeplankton productivity and are expected to reduce the trade-offof CO2 towards the sea bed.

So, the ocean system is being threatened by the anthropogenic
activities which are causing global warming and ocean acidification. As waters warm up and the chemical composition of theocean changes, the fragile equilibrium that sustains marine biodiversity is being disturbed with serious consequences for themarine ecology and for earth’s climate. There is already someclear evidence that the global warming trend and increasing
emissions of CO2 and other greenhouse gases are affecting environmental conditions and biota in the oceans on a global scale.
However, we neither fully appreciate nor do we understand how
significant these effects will be in the near and more distant future. Furthermore, we do not understand the mechanisms andprocesses that link the responses of individuals of a given species with shifts in the functioning of marine ecosystems (Valdés
et al., 2009). Marine scientists need urgently to address climatechange issues, particularly to aid our understanding of climatechange effects on ecosystem structure, function, biodiversity,and how human and natural systems adapt to these changes.
27Fact box 3. The role of ocean viruses and bacteria in the carbon cycle
Free living marine microorganisms (plankton, bacteria and viruses) are hardly visible to the human eye, but account for up to
90% of living biomass in the sea (Sogin et al., 2006; Suttle, 2007).
These microscopic factories are responsible for >95% of primary
production in oceans, producing and respiring a major part of the
reduced carbon or organic matter (Pomeroy et al., 2007).
PlanktonMore than 36.5Gt of CO2 is captured each year by planktonic
algae through photosynthesis in the oceans (Gonzalez, et al.
(2008). Zooplankton dynamics are a major controlling factor in
the sedimentation of particulate carbon in open oceans (Bishop
and Wood, 2009). Of the captured CO2, and an estimated 0.5Gt
C yr–1 is stored at the sea bed (Seiter et al., 2005).
Marine viruses and bacteria – significant in the carbon budget
Marine viruses require other organic life to exist, but in themselves have a biomass equivalent to 75 million blue whales(11.25Gt). The estimated 1x1030 viruses in the ocean, if stretchedend to end, would span farther than the nearest 60 galaxies (Suttle, 2007). Although the story of marine viruses is still emerging,
it is becoming increasingly clear that we need to incorporate viruses and virus-mediated processes into our understanding ofocean biology and biogeochemistry (Suttle, 2007).
Interactions between viruses and their hosts impact several important biological processes in the world’s oceans including biogeochemical cycling. They can control carbon cycling due to cell lysis
and microbial diversity (by selecting for various hosts) (Wiggington,2008). Every second, approximately 1x1023 viral infections occur inthe ocean and cause infection of 20–40% surface water prokaryotes
every day resulting in the release of 108–109 tonnes of carbon per28

day from the biological pool within the oceans (Suttle, 2007). It isthought that up to 25% of all living carbon in the oceans is madeavailable through the action of viruses (Hoyle and Robinson, 2003).
There is still a critical question as to whether viruses hinder or
stimulate biological production (Gobler et al., 1997). There is an
ongoing debate whether viruses (1) shortcircuit the biologicalpump by releasing elements back to the dissolved phase (Poorvin et al., 2004), (2) prime the biological pump by accelerating
host export from the euphotic zone (Lawrence and Suttle, 2004)or (3) drive particle aggregation and transfer of carbon into thedeep sea through the release of sticky colloidal cellular components during viral lysis (Mari et al., 2005).
Bacteria
Ocean bacteria are capable of taking up CO2 with the help of
sunlight and a unique light-capturing pigment, proteorhodopsin,which was first discovered in 2000 (Beja et al., 2001). Proteorhodopsin can be found in nearly half of the sea bacteria. Knowledgeof marine bacteria may come to be of major importance to ourunderstanding of what the climate impact of rising CO2 emissions means for the oceans.
Life deep below the sea bed
Life has been shown to exist in the deep biosphere, even 800m
below the sea floor. It is estimated that 90 Gt of microbial organisms (in terms of carbon mass) are living in the sediments androcks of the sea bed, with bacteria dominating the top 10 cm, butmore than 87% made up by a group of single cell microorganisms
known as Archaea. It is still not clear what their ecological functions are, or even how they survive in such a low flux environment,
living on previously digested fossil remains (Lipp et al., 2008).

SEVEN DETRIMENTAL WAYS IN WHICH THE
OCEANS THEMSELVES WILL BE AFFECTED
BY CLIMATE CHANGE
The ecology of the planet is closely linked to different ocean processes, most of which are
directly affected by climate change.

OF
1 MELTING
ARCTIC SEA ICE

Arctic sea-ice reductions have significant impacts on climate,
wildlife and communities. The opening of open water acrossthe Arctic ocean will have unknown consequences in terms ofchanges in water circulation and redistribution of species fromthe Atlantic and Pacific oceans. As sea ice coverage declines, albedo diminishes and more radiation is absorbed by the sea water, ina feed-back process that enhances warming and melting sea ice.

Sea ice anomaly in Northern Hemisphere

Million square kilometres, from 1978-2000 average
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
2000

2002
2001

2004
2003

2006
2005

2008
2007

2010

2009

Source : NOAA, 2009.

Figure 9: Loss of the ice sheet.

29

Sea level anomalies

-0.25

-0.20

-0.15 -0.10

-0.05

0

0.05

0.10

0.15

0.20

0.25 and more

(Metres)

Source: IPCC, 2007.

Figure 10. Sea level anomalies (see text).

CIRCULATION AND
2 OCEANTHERMAL EXPANSION

Melting and warming will have consequences on ocean circulation, as ocean currents are driven by the interactions
between water masses though balance in temperature andsalinity, in other words, their density. Additionally melting of
inland glaciers and continental ice sheets on Greenland andAntarctica, and the thermal expansion of ocean waters are
causing sea level rise.
30

FREQUENCY AND
3 INCREASEDSEVERITY OF STORM EVENTSHigher water temperatures lead to increased evaporation,
making more energy available for the atmosphere, which
boosts the destructive force of extreme weather events likehurricanes, typhoons etc.

Figure 11. Trends in number of reported disasters (see text).

Number of disasters per year
450

Trends in number of reported disasters
Much of the increase in the number of hazardous
events reported is probably due to significant
improvements in information access and also to
population growth, but the number of floods andcyclones reported is still rising compared toearthquakes. Is global warming affecting thefrequency of natural hazards?

400
All disasters
350

All disasters include:
drought, earthquake,
extreme temperatures,
famine, flood, insect
infestation, slides,
volcanic eruption, wave
and surge, wild fires,wind storm.

300

250

250

200

200

Earthquakes
versus climatic disasters
150

150

Floods100

100

Earthquakes

50

50

0

Earthquakes

Cyclones

0

1900
1920
1940
1960
2000
1980
Source: CRED Annual Disaster Statistical Review 2006, 2007.

2010

1980

1985

1990

1995

2000

2005

2010

Figure 12. Projected population flooded in coastal areas by 2080 (see text).

Population flooded in coastal areas in 2080
Million people per year (logarithmic scale)1000

no additional efforts undetaken
more protection efforts than today
strong efforts to protect coastal populations against floods

100

Note: The upper margin of each band shows the amount ofpeople affected in the A2 scenario according to which global
population will reach 14 thousand million by 2080 with thelowest GDP of all IPCC scenarios. Therefore little capacity
exists to adapt, and more people will be affected by floods.
The lower end of each curve shows the impact for the A1/B1
scenario assuming the highest per captia income and world
population at 8 thousand million, allowing for higher
investments in the protection of the population.

10

1

Sea-level rise

0.1
0

0.25

0.50

0.75

1.00

Metres

Source: H. Ahlenius, GEO Ice and Snow, 2007, based on Nicholls, R.J. andLowe, J.A., 2006.

31

STRATIFICATION AND
4 WATER-COLUMNLOSS OF COASTAL PUMPS

Warming and melting is enhancing seasonal water-column stratification in the ocean on a global scale, mainly in temperate seas.
Some coastal ”flushing” mechanisms – so-called dense-shelf watercascading – may also be weakened with climate change, resulting
in slower “cleaning” of polluted coastal waters, more algae blooms
and dead zones, and lack of transport of food particles to organisms
living in the deep sea and on the sea floor. The resulting reduction
in nutrient flux will cause a decline in primary production and possibly in ocean productivity.

6 OCEANACIDIFICATIONThe ocean is absorbing excess CO2 from the atmosphere which is causing changes in the biogeochemical carbonate balance of the ocean, and thus significant acidification of ocean waters. The ocean is thus
somehow alleviating the impacts of global warmingin the biosphere. With climate change and ocean acidification a large reduction in the ability of the ocean
to take up atmospheric CO2 is expected. The reduction of pH and calcium carbonate saturation levels in
the oceans will affect thousands of species from thewide range of marine organisms which need carbonate in their development and for forming shells andSHIFTS IN DISTRIBUTION OF SPECIES
skeletons. The structure of marine ecosystems are exAND MIGRATORY ROUTES
pected to be severely impacted by acidification withThe distribution of plankton, fish and other marine fauna has shiftpotential extinctions and large-scale reduction in bioed hundreds of kilometers toward higher latitudes, especially in thediversity and ecosystem services, primarily because
North Atlantic, the Arctic Ocean, and the Southwest Pacific Ocean.
19581982- 1981- 19991982 has- 19991982
2000- 1999- 2002
2000 - 2002of the speed
2000 -at2002
which these water chemistry changes
Additionallyocean warming
noticeable
effectsonthe migratory
are occuring.
routes of many species.

581

1958 - 1981

1982 - 1999

2000 - 2002

Global ocean acidification
Oceanic CO2
concentration

1958–1981

1982–1999

2000–2002

Mean number of species
Meanpernumber
CPRnumberofsamplespeciesMeanpernumberCPR
sampleofsample
species per CPR sample
Meanofspecies
per CPR
0.0

0.0

0.1

0.1 0.0
0.1
Source: based on0.0
Ahlenius, H., 2008; Personalcommunication 0.1
with Chris Reid, SAHFOS, November 2007.

Ocean water
acidity

atm

pH

380

8.14

360

8.12

340

8.10

320

8.08

300

8.06

Figure 13. Plankton migration shift.
 Figure 14. As carbon concentrations in the atmosphere increase, so

do concentrations in the ocean, with resultant acidification as a naturalchemical process.
32

1985 1990 1995 2000 20051985 1990 1995 2000 2005

Source: IPCC, 2007.

1994
Figure 15. Ocean
acidification – ascarbon concentrations increase in
the atmosphere, so
do concentrationsin the oceans, withresultant acidification.

1994

2100

2100

Aragonite saturation

Aragonite saturation
Supersaturation

Supersaturation

Undersaturation

Undersaturation

Map by Hugo Alhenius.
Source:Donner,S.D., etal.,J.C.,
2005;
Orr, J.C., 2005.
Sources: Donner,S.D.,
et al., 2005;
Orr,
2005.

Map by Hugo Alhenius.
Sources: Donner, S.D., et al., 2005; Orr, J.C., 2005.

OF CORAL REEFS AND
7 LOSSASSOCIATED MARINE BIODIVERSITY

Coral bleaching is a phenomenon caused primarily by above-average water temperatures and high radiationfrom the sun, that stress the micro-algae (“zooxanthellae”) living symbiotically in corals and giving them
their spectacular colours. When these micro-algae become stressed, the coral expels them, so that the coral’s
white calcareous skeleton is visible through the transparent tissue – hence the term ‘bleaching’. Bleachedcorals are very weak and prone to disease, algal overgrowth and mortality if the stress is high or continues
over longer time periods. In 1998, a mass global bleaching event caused the mortality of an estimated 16%of the world’s coral reefs, and unfortunately because of rising sea temperatures mass bleaching events are
predicted to increase in frequency and intensity. Loss of coral reefs also means loss of revenue and food forcoastal communities who depend on them.
33

34

BLUE CARBON – THE ROLE OF
OCEANS AS CARBON SINKS
Vegetated coastal habitats – mangrove forests, salt-marshes and seagrass meadows –have much in common with rain forests: they are hot spots for biodiversity, they provide
important and valuable ecosystem functions, including a large carbon sink capacity, andthey are experiencing a steep global decline (Duarte et al., 2008, Duarte, 2009). Indeed,
the world is losing its coastal habitats four times faster than its rain forests (Duarte et al.,2008, Duarte, 2009) and the rate of loss is accelerating (Waycott et al., 2009). However,whereas society is well informed of the benefits and threats associated with rainforests,
there is a comparative lack of awareness on the status and benefits of vegetated coastal
habitats. This is perhaps because of a “charisma” gap, where these often submerged, outof sight coastal habitats, are not as appealing to the public as their terrestrial counterparts(Duarte et al., 2008). Yet, because of their similar functions and threats, coastal habitats
can be considered as blue carbon sinks.

BLUE CARBON SINKSOne key function of vegetated coastal habitats is their role ascarbon sinks. Benefiting from the excellent conditions available to support plant growth, vegetated coastal habitats rank
amongst the most productive habitats in the world, comparable
in production to the most productive agricultural crops (Table 1,
Duarte and Chiscano, 1999). Much of their production is used
to support ecosystem functions (Duarte and Cebrián, 1996).
However, blue carbon sinks are strongly autotrophic, whichmeans that these ecosystems fix CO2 as organic matter photosyntheticaly in excess of the CO2 respired back by biota (Duarte
and Cebrián, 1996; Gattuso et al., 1998; Duarte et al., 2005a),thus removing CO2 from the atmosphere. Some of this excesscarbon is exported and subsidises adjacent ecosystems, including open ocean and beach ecosystems (Duarte and Cebrián,
1996; Heck et al., 2008; Bouillon et al., 2008). The remaining

excess production of mangrove forests, salt-marshes and seagrass meadows is buried in the sediments, where it can remain
stored over millenary time scales (Mateo et al., 1997), thereby
representing a strong natural carbon sink. This is most evident
in the case of seagrass meadows, which accumulate enoughmaterials as to significantly raise the seafloor, forming matsthat can exceed 3 metres in depth.
In addition to burying a fraction of their own production, blue
carbon sinks reduce flow, alter turbulence and attenuate wave
action (Koch et al., 2006), thereby promoting sedimentation
and reducing sediment resuspension (e.g. Gacia and Duarte,2001). Recent research has shown that the canopies of seagrassmeadows trap particles entrained in the flow, which lose momentum upon impacting on the leaves, thereby promoting thesedimentation of suspended material to the seafloor (Hendriks35

Habitat lost
since 1940s

30%

25%

20%

15%

10%

5%
Source: UNEP-WCMC, 2009;
Valiela et al., 2001

Mangroves

Loss rate per
year inrecent times

0%

30%

25%

Habitat lost
since 1940s

20%

15%

10%

5%
Source: UNEP-WCMC, 2009;
Duarte et al., 2008.

36

Salt Marshes
0%

Habitat loss
rate per year
in recent times

Habitat lost
since 1940s
30%

25%

20%

15%

10%

Loss rate per
year inrecent times

5%
Source: UNEP-WCMC, 2009;
Waycott et al., 2009.

Seagrass
0%

Figure 16a–c: Distribution of the world’s blue carbon sinks – seagrasses, mangroves, and salt marsh communities (Source: UNEP-WCMC).
et al., 2007). Isotopic analyses of the organic carbon accumulated in sediments of vegetated coastal habitats have shown thata significant fraction derives from plankton (Gacia et al., 2002).
On the continental shelf and in estuaries, terrestrial sources ofcarbon are also significant (Bouillon et al., 2008), adding to thecarbon sink capacity of these blue carbon sinks.
A consequence of the capacity of vegetated coastal habitats toaccumulate materials in the seafloor is that they act as efficientcarbon sinks, globally responsible for the burial of 120–329 Tg
C yr–1, which accounts for at least half of the lower estimate
for global carbon burial in marine sediments (Table 1). Blue
carbon sinks therefore play a major role in the oceanic carbon
cycle (Duarte et al., 2005a). The carbon burial capacity of marine vegetated habitats is phenomenal, 180 times greater than
the average burial rate in the open ocean.
Carbon burial in the ocean represents slightly over 10% of the oceanic carbon sink capacity (up to 25% using maximum estimates,
Table 1, see below), estimated, from observations and inverse

models, to be about 2,000 Tg C year–1 (Sarmiento and Gruber,
2002). However, this 2,000 Tg C year–1 is the carbon annuallytransferred from the atmosphere to the oceans, where it is largely
stored as dissolved inorganic carbon. The long-term residenceof anthropogenic CO2 in the oceans is uncertain, as this carbon
does not penetrate deep enough to remain in the ocean overextended time scales. Indeed, half of the anthropogenic carbon
stored in ocean waters is contained within the top 400 metres,
where it may equilibrate back to the atmosphere within a few decades, and the amount present in the deep ocean – where it may
remain over much longer time scales – is below the detection
limit (Sabine et al., 2004). Only a minute amount of the carbon
taken up by the oceans is preserved in the deep-sea sediments,
where it is effectively buried over long periods of time, representing 6 Tg C yr–1, with a carbon burial per unit area of seafloor 180
times lower than the rate for blue carbon sink sediments (Table1). In addition, there are concerns that the capacity of the watercolumn of the oceans to act as a sink for atmospheric carbon
will weaken in the future, and there is evidence that it may havestarted to do so (Doney et al., 2009). Hence, only carbon seques37

tered in marine sediments, as in the case of blue carbon sinks,
can be safely considered to represent a long-term marine carbon
storage. Blue carbon sinks, which cover less than 0.2% of the seafloor, contribute about 50% (71% using maximum estimates, see
Table 1) of the total burial of organic carbon in ocean sediments
and therefore rank amongst the most intense carbon sinks inthe biosphere (Duarte et al., 2005a). Yet coastal vegetated habitats
have been neglected from accounts of the global carbon cycle andglobal inventories of natural carbon sinks.
Blue carbon sinks are built by plants and trees (otherwise
known as angiosperms such as mangroves, salt-marsh plants
and seagrasses) but the coastal ocean also contains vast areas
covered by algal beds. Most macroalgal beds (including kelp
forests) do not bury carbon, as they grow on rocky substrates
where burial is impossible.

UNCERTAINTY AND UPPER ESTIMATES OF
CARBON SINK BY BLUE CARBON SINKS

There is uncertainty about these global rates, due to uncertainties in their areal extent as well as variability in carbon burial
rates among individual ecosystems, although independent
estimates for some ecosystems, such as mangrove forests,
agree remarkably well (Bouillon et al., 2008). For instance, estimates of the area covered by mangroves, probably the best
constrained amongst vegetated coastal habitats, ranges from
0.11 to 0.24 million sq km (Bouillon et al., 2008). Estimatesof the area covered by seagrass meadows, the least constraint
estimate, range from a documented area of 0.12 million sq km(Green and Short, 2003), to an upper estimate of 0.6 million
sq km (Duarte and Chiscano, 1999) as the South East Asianarchipelagos, such as Indonesia, are likely to hold vast, uncharted seagrass meadows (Duarte et al., 2009). Indeed, thecoastal area with sufficient submarine irradiance as to support
seagrass meadows has been estimated at 5.2 million sq km(Gattuso et al., 2006). Hence, a thorough inventory of blue
carbon sinks may well yield a cover twice as large as the mean
area considered in current, conservative global assessments(Table 1). Individual blue carbon sink ecosystems also vary
greatly in their capacity to bury carbon, with the maximum
reported rate corresponding to 17.2t C ha–1 yr–1 in a salt marsh(Table 1). The maximum carbon burial rates for any one habitat type are 3 to 10 times higher than the global mean value
for these ecosystems (Table 1), providing evidence of the very38

large carbon sink capacity of some specific vegetated coastal habitats. Indeed,
the maximum reported carbon sink capacity of salt-marsh, mangrove and seagrass ecosystems (Table 1) exceeds by over 10, 6 and 2 fold that of undisturbed
Amazonian forest, estimated at 1.02 t C ha-1 (Grace et al., 1993). For instance,
carbon burial by salt marshes, which cover a small area of the conterminous
USA, has been estimated to account for 21% of the total carbon sink of all USA
ecosystems (Bridgham et al., 2006). Hence, an upper estimate of the carbon
capture capacity of blue carbon sinks can be derived by combining maximum
estimates of the area covered globally with upper estimates of the carbon buried per unit area (Table 1). These calculations yield an upper estimate for the
carbon capture capacity of blue carbon sinks at 329 Tg C year–1, accounting for
71% of the burial of organic carbon in the ocean (Table 1).
Table 1. Mean and maximum (in brackets) estimates of the area covered by blue
carbon sinks and the annual organic carbon burial rates. Carbon burial rates arepresented per hectare (mean,range and , the upper confidence limit of the meanof individual ecosystem estimates, in brackets) and globally (as reported rangesof mean rates of global carbon burial derived using different methods and, inbrackets, an upper estimate derived using the maximum area and the upper confidence limit of the mean burial rate). The data is for vegetated coastal areas andtheir percentage contribution to carbon burial in the coastal and global ocean (inbrackets the burial rate and percentage contribution of vegetated habitats calculated from the upper estimates). Total burial rates of organic carbon in estuarine
and shelf sediments and deep-sea sediments are provided for comparison. Data
derived from reviews by Cebrián and Duarte (1996), Duarte et al. (2005a), andBouillon et al. (2008).
Component
Vegetated habitats
Mangroves
Salt Marsh
Seagrass
Total vegetated habitats
Depositional areas
Estuaries
Shelf
Total depositional areas
Total coastal burial% vegetated habitats
Deep sea burial
Total oceanic burial% vegetated habitats

Area
Million km2

Organic Carbon burial
Tg C y-1
Ton C ha-1 y-1

0.17 (0.3)
0.4 (0.8)
0.33 (0.6)
0.9 (1.7)

1.39, 0.20 – 6.54 (1.89)
1.51, 0.18 – 17.3 (2.37)
0.83, 0.56 – 1.82 (1.37)
1.23, 0.18 – 17.3 (1.93)

17 – 23.6 (57)60.4 – 70 (190)
27.4 – 44 (82)
114 – 131 (329)

1.8
26.6

0.5
0.2

330.0

0.00018

81.0
45.2
126.2
237.6 (454)46.89 (0.72)
6.0
243.62 (460)45.73 (0.71)
39Fact box 4. Ocean carbon in the global cycle?

40

Several studies suggest that the oceans have taken up around2,000–2,200 Tg C yr–1 over the past two decades (Gurney etal. 2002, Plattner et al. 2002, Sabine et al. 2004, Bender et al.
2005, Miller et al. 2005, Manning and Keeling 2006). The uptake increased slightly from around an estimated 1800 in the
1980s, to 2,200 Tg C yr–1 in the 1990s and the first half decadeof the twenty-first century (McNeil et al. 2003, Canadell et al.
2007). However, only a portion of this carbon is actually stored
permanently in the oceans, as much is recycled and releasedback within a few decades. Coastal ecosystems are currently
storing an amount of carbon equivalent to around 25% of theestimated annual increase of approximately 2,000 Tg C yr-1 inthe atmosphere.

mented (including slowing deforestation and wide afforestation
programmes), would by 2050 according to the IPCC amount to approximately 12–15% of the required emission reductions. Preventing
the loss of the oceans blue carbon sinks would mean a significant
contribution to reducing climate change, even compared to slowing
deforestation of tropical rainforests. Afforestation programmes ofmangroves could enhance this even further. The upper estimate ofstorage in oceans is approximately 450 Tg C yr–1 – equivalent near
10% of the required emission reductions. Hence, “Blue” and “Green”
carbon combined could bind at least 25% of the projected required
emission reductions.

Currently, fossil fuel emissions are estimated at 7,200 Tg C yr–1,
which results inapproximately 2,000 Tg C yr-1 increase in theatmosphere per year. Losses of seagrass communities, mangroves, and salt marshes have accelerated from around 0.9%
per year in the first three quarters of a century to up to 7% peryear in the more recent decades. Under current scenarios, mostblue carbon sinks will be lost in the next two decades leading
to a loss of annual carbon binding capacity equivalent to 4–8%
of the total anthropogenic input. Hence, total emissions would
therefore have to be reduced by an additional 4–8% by 2030 toretain the status quo, or 10% by 2050. In comparison, the total
gain estimated from the UN REDD programme if fully imple-

7200 ± 300
6400 ± 300
5200 ± 300
Fossil fuel emissions
Atmospheric increase –2900 ± 100 –3200 ± 200 –4200 ± 100–1900 ± 600 –2200 ± 700 –2200 ± 400
Oceanic uptake–800 ± 800–100 ± 800–400 ± 700
Net terrestrial flux
1500 ± 800
1600 ± 800
1500 ± 800
Land-use change
Residual terrestrial flux –1900 ± 1100 –2600 ± 1100 –2300 ± 1100

1980s
(Tg C yr–1)

1990s(Tg C yr–1)

2000–2005(Tg C yr–1)

Table 2. The Global carbon budget Tg C yr–1 – around 2,200 Tg C
are captured per year in oceans, but only a portion of it is stored,
mainly in sediments in oceans blue carbon sinks, such as mangroves, marshes and seagrass communities (Canadell et al., 2007;
Houghton, 2007).

Blue carbon sink

Salt marshes

Fact box 5. Geo-engineering proposals
for mitigating CO2
Mangroves

Seagrasses

0.2
0.4
0.3
1.8
Shelf
Estuaries
Deep Sea

26.6

Organic carbon burial rate
Teragrams per year
Maximum
Marine habitat area
Million square
kilometres

330

Minimum
Average
17.5

6.5

1.80
Source: Cebrián and Duarte,
1996; Duarte et al., 2005a;
and Bouillon et al., 2008.

0.0002

Interest has been growing in the use of geo-engineering to provide a technically and potentiallycommercially viable mitigating solution to combat
increasing atmospheric CO2 concentrations (see
IPCC, 2005 for an overview). Several of these proposals intend to enhance the function of the ocean
as a carbon sink, or to store CO2 in subsea geological formations. Some of these suggestions mightsound dramatic and farfetched, but if the concepts
are scientifically sound and technically feasible, theyshould not be disregarded. However, evaluatingthese new innovations is in most cases not a simple
story, as they pose significant ecological, economic, political and ethical challenges (Nature News,
2009) giving cause for concern. With too many unknown variables and current modeling limitations,assessment of the risks and consequences of these
proposals will be a challenge.
There are two main approaches. The first is to reduce energy entering the earth’s system by blocking radiation so it cannot be absorbed in the first
instance (e.g. spraying aerosols to increase cloud
cover, use of solar shades, increasing reflective capacity of urban areas); the second is to reduce theconcentration of CO2 in the atmosphere by transferring it into long term storage reservoirs, thereby
facilitating the escape of energy from the earth(Lenton and Vaughn, 2009; IEA, 2004). These approaches are at varying degrees of development;
while some have been through in-situ experimentation, others are still just theoretical. Current research shows that most ocean geo-engineering
concepts are high risk for undesirable side-effects(e.g. increase in ocean acidification), have limited
application, uncertain outcome and potentiallynon-reversible impacts on the marine environment.
This highlights the need to apply a precautionary
approach when investigating ocean geo-engineering interventions.

Figure 17: Blue carbon sinks.
41

Table 3. An overview of the main ocean carbon cycle geo-engineering proposals, the concept behind these ideas and current status
of investigation.
ProposalConcept

Status of research

Ocean fertilization

Primary production in some areas of the ocean is limited by macro or micro nutrients (such as iron, silica,
phosphorus or nitrogen). By increasing the availabilityof these nutrients, primary productivity could be increased resulting in an acceleration of the natural rateof CO2 uptake by the oceans from 2 Gt C yr–1 (Huesemann, 2008) and increase CO2 storage in the deep sea.
Any CO2 stored in this way would be removed from theglobal carbon cycle for up to 1,000 years.
Promoted by commercial groups and enterprises (e.g.
Climos) and with potential for trading credits on thevoluntary carbon market.

• Approximately 13 small scale in situ experiments havebeen conducted since 1993, but have proven inconclusive about the CO2 sequestration effectiveness ofocean fertilization;• To make a viable contribution to reducing atmospheric CO2 concentrations, ocean fertilization would haveto be carried out over large areas, and potentiallywould need to be sustained on a millennial timescale(Lenton and Vaughan, 2009);• International concern has been expressed, inter alia,
about the high ecological risks. International bodies
and experts have called for restrictions and caution(e.g. IMO, 2007; CBD 2008; Gilbert et al., 2008; Seibel and Walsh 2001);• Parties to the London Convention agreed that, given
the present state of knowledge, ocean fertilization
activities other than legitimate scientific researchshould not be allowed. An assessment framework for
future scientific research and in-situ experiments isunder development (IMO, 2008).

Altering ocean mixing

Use of 200m long ocean pipes to enhance the mixing
and upwelling of nutrient rich waters (e.g. Lovelock and
Rapley, 2007);
Enhance downwelling by using floating pumps tocool waters and form and thicken sea ice (Zhou andFlynn, 2005)• Never reached field trial stage;• Calculations indicate sequestration flux that would beachieved is trivial on any meaningful timescale; andcostly (Lenton and Vaughan, 2009).

Increasing ocean alkalinity

Increasing the alkalinity of the oceans by:• Adding carbonate, thereby increasing the capacityof the water to absorb CO2 (Kheshgi, 1995). Harvey(2008) suggested the use of finely ground limestone,
other proposals foresee the use of thermally decomposed limestone (Cquestrate, 2009);• Enhancing the solubility of CO2 in the oceans by a process equivalent to the natural silicate weathering reaction. HCl is electrochemically removed from the ocean
and neutralized through reaction with silicate rocks.

• This is as yet highly theoretical, but under active research, e.g. by Cquestrate, which is an opensource
project to explore the idea, encouraging evidence
based debate and investigation (Cquestrate, 2009);• It is possible that the CO2 emissions generated frompreparing the carbonate material would match theCO2 sequestered (Lenton and Vaughan, 2009).

42

Proposal

Concept

Status of research

The increase in ocean alkalinity resulting from theremoval of HCl causes atmospheric CO2 to dissolve
into the ocean where it will be stored primarily as
HCO3-. (House et al., 2007);• These are the only marine geo-engineering proposals
that would remove CO2 from the atmosphere withoutcausing an increase of ocean acidification.
Geological carbon storage

Injection of CO2 into deep geological formations suchas saline aquifers or depleted oil and gas reservoirs below the sea floor• In operation since 1996. Measures and guidance(e.g. to reduce the risk from leakages) were adopted
by international bodies (IMO/London Convention,
OSPAR). Studies have being conducted to research
and model long term consequences and how securesuch storage would be (e.g. Gilfillan et al., 2009,
Statoil Sleipner Project)

Dissolution injectionof CO2 into the watercolumnCO2 injection onto thesea floor

CO2 is transported by ship or pipeline offshore and theninjected into the water column at great depth (>1000m
or deeper) where the CO2 dissolves and remains isolated from the atmosphere for centuries. (UNESCOIOC/SCOR, 2007);
CO2 is placed directly onto the sea floor at depths greater than 3000m, where the CO2 would form long-lasting‘lakes’ with low dissolution rates.

• Both concepts been subject to years of theoreticalresearch/modeling and some small scale field experiments, but have yet been deployed or fully tested(UNESCO-IOC/SCOR, 2007). Research indicatesthat there would be a gradual release of injected CO2
back to the atmosphere over a timescale of hundredsof years to millennia (depending on depth and local
site conditions);• There is no known mechanism for preventing catastrophic acute release of injected CO2 (UNESCOIOC/SCOR, 2007), there are significant environmental risks and impacts associated with these proposed
methods of storage (IPCC, 2005; Sedlacek et al.,2009). Injection of CO2 into the water column or on
the sea bed affects marine organisms nearby andocean chemistry (e.g. by increasing acidity). In thelight of the potential for severe environmental impact, the placement of carbon dioxide streams in thewater column or on the sea bed has been prohibitedin 2007 via the amendment of the London Convention Protocol and in a legally binding decision agreed
under OSPAR (OSPAR, 2007).

43

44

THE WORLD’S OCEAN CARBONSINKS IN RAPID DECLINE
Vegetated marine coastal habitats, blue carbon sinks, rank amongst the most threat­ened marine ecosystems (Duarte et al., 2008; Duarte 2009). Coastal eutrophication,
reclamation, engineering and urbanisation have lead to the loss of a substantial fractionof the earth’s blue carbon sinks since the 1940s (Duarte et al., 2008; Duarte 2009)
A recent assessment indicates that about one-third of the global seagrass area has been already lost, and that these losses areaccelerating, from less than 0.9% year–1 in the 1970’s to morethan 7% year–1 since 2000 (Waycott et al., 2009). About 25%of the area originally covered by salt-marshes has been globally
lost (Bridgham et al., 2006), with current loss rates at about 1
to 2% year–1 (Duarte et al., 2008). Valiela et al. (2001) estimatedthat a total of about 35% of the area once covered by mangroves
had been lost globally since the 1940s, with current loss rates

Southern Ocean carbon sink change

Fact box 6. Is the ability of the Southern Oceans
to bind carbon also weakening?

Gigatonnes of carbon per year
1.5

The Southern Oceans are recognised as an important carbon
sink currently taking up approximately 15% of anthropogenic CO2(CSIRO, 2007). Models predict that as the atmospheric concentration of CO2 increases, so should the ocean’s absorbtive capacity.
This seems to be happening in most areas, but not so in the Southern Ocean (CSIRO, 2007; Le Quéré et al., 2007; Lenton and Metzl,
2009). Whilst scientists agree on the data, there is some debate as
to why this may be – possibly decreased ozone with increased GHG
leading to stronger winds and therefore greater mixing, but despite
the cause, this trend has potentially serious implications for amtmospheric CO2 concentrations in coming years.

1.0
0.5
0.0
-0.5

at about 1 to 3% year–1. Hence, about one-third of the area coveredby blue carbon sinks has been lost already and the rest is severely
threatened. Marine vegetated habitats, blue carbon sinks, rank
amongst the most threatened habitats in the Biosphere, with global
loss rates 2 to 15 times faster than that of tropical forests (0.5% year–1,
Achard et al., 2002). The loss of blue carbon sinks represents, inaddition to the impacts on biodiversity and coastal protection involved, the loss of a natural carbon sink, eroding the capacity of thebiosphere to remove anthropogenic CO2 emissions.

Expected-1.0-1.5
Observed-2.0
1970
Source : NASA, 2008.

1980

1990

2000

 Figure 18: Declining ability of the Southern ocean’s ability toabsorb CO2.
45

25Blue carbon sink burial rates
tons of carbon per hectare per year

Salt marshes

20

15

Mangroves
10

Estuaries
5

Seagrass
Deep sea

- - -

-

-

Shelf
0
-

-

-

Teragrams of carbon per hectare per year
-

-

-

-

-

-

-

-

-

-

-

Maximum burial rate
-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Sources: Cebrian and Duarte, 1996; Duarte et al., 2005.
-

-

-

-

-

-

-

-

-

-

-

-

-

-

Average burial rate

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

46

-

-

-

-

-

-

Total annual blue carbon sink burial rates
Estuaries
100

Salt
marshes

80

60

Shelf
Seagrasses
40

Mangroves

Deep sea
20

- - -

-

0
-

-

-

-

-

-

-

-

-

-

-

-

-

-

Maximum burial rate
-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Sources: Cebrian and Duarte, 1996; Duarte et al., 2005.
-

-

-

-

-

-

-

-

-

-

-

-

-

-

Average burial rate

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Teragrams of carbon per year

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Figure 19a–b:
The capacity ofocean’s blue carbon sinks.
47

48

49

50

OCEANS’ BLUE CARBON SINKSAND HUMAN WELLBEING
Aquatic ecosystems provide services that contribute to human welfare, both directly andindirectly. These may be recognized by their direct benefits, such as sources of employ­ment, income and food security, tourism, scientific research and mineral extraction; bytheir indirect benefits, such as climate regulation and transportation; and by their intrin­
sic value, such as the conservation of biodiversity and social identities and their continu­
ation to support future generations (Kay and Alder, 2005).
It is estimated, that the average annual value of services fromthe world’s coastal ecosystems exceeds US$25,000 billion peryear (Martínez et al., 2007). Hence, the coastal zone is of major
economic importance today much as it has been throughout
human history.

as resources come under greater pressure, and availability andaccess to, for example, fish supplies will become an increasingly
critical development issue (Cochrane et al., 2009; FAO, 2008).

Climate change is projected to impact across ecosystems, societies and economies, increasing pressures on all livelihoods andfood supplies, including those in the fisheries and aquaculture
sector. Maintenance of food quality will have a more pivotal role

The climate change induced alterations which the oceans will
experience, including increasing temperatures, acidification andchanges in currents will ultimately affect fisheries and aquaculture. Fish distributions are predicted to change, and already we

IMPACTS TO FOOD SECURITY THROUGH
THE OCEANS AND COASTSFish catch
Fish catch
Tonnesperper
Tonnessquarekilometre
kilometresquareand more
55 and
more
to 55
33 to
to 33
11 to
0.5 toto 11
0.5
0.25 toto 0.50.5
0.25
0.2 to 0.25
0.25

Sources:Usbased
based
on Alhenius,
Alhenius,
H., 2008;
2008; FAO,
FAO, 2008.
2008.
Sources:on
H.,
Source: based on Alhenius, H., 2008; Sea Aroundproject,
personal communication
October 2007 (University of British Columbia).

Figure 20: The worlds most productive fishing grounds are confined tomajor hotspots in around 7.5% of
the ocean surface, where over halfof the fish are caught.
51

91 000

Current ranges of total valuation estimatesof blue carbon sinks per hectare

MangrovesFigure 21: Although coastal ecosystems
are already among the most valuable on
the planet, the current estimates of theeconomic value for some of the oceans
blue carbon sinks are surprisingly low.
How should human perception ofthese important ecosystems change as
we learn of the vast benefits of maintaining healthy coasts and oceans?

15 000

Seagrass

Coral reef
10 0005 000

Deep seaSalt
marshes

Coastalplankton
-

- -

0
-

-

-

-

-

-

-

-

Ranges of different values
found in literature
-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Ecosystem service value per hectare
US dollars
-

-

-

-

-

Sources: Martinez et al. 2007; Gunawardean andRowan, 2005; Spurgeon, 2004; Costanza, 1997.
-

-

-

-

-

-

-

52

-

-

-

-

-

-

-

- - -- - - - - --- -- - - - -- -- - - - - - - -- - - --

-

-

-

-

Fact box 7. Healthy aquatic ecosystems contribute to food security and livelihoods• Fisheries and aquaculture contribute significantly to food security and livelihoods, but depend on healthy aquatic ecosystems.
These contributions are often unrecognized and undervalued.
• Over 500 million people in developing countries depend, directly or indirectly, on fisheries and aquaculture for their livelihoods. Fish (including shellfish) provides essential nutrition for
3 billion people and at least 50% of animal protein and essential
minerals to 400 million people in the poorest countries.
• Aquaculture is the world’s fastest growing food production
system, growing at 7% annually – but the production of externally fed aquaculture (48% of total aquaculture production) is largely dependent upon marine fisheries for feed.
• Fish products are among the most widely traded foods, withmore than 37% by volume of world production traded internationally.
• Natural barriers such as sand dunes, mangrove forests andcoral reefs dampen the impacts of a range of coastal hazards, including storm/cyclone surges and tsunami waves,
helping to protect coastlines from their full impact.
Source: PaCFA, 2009are seeing shifts in species distributions in the North Sea withnearly two thirds of the commercially important species shifting northward in mean latitude or deeper in depth or both since1970 (Perry et al., 2005; Dulvey et al., 2008). Recent projectionsof changes in the distribution ranges of more than 1,000 commercially important fish species, based on climate change scenarios to 2050 predict numerous species extinctions in sub-polar
regions, the tropics and semi-enclosed seas (Cheung et al., 2009).
Climate change will also impact the levels of invasive marine organisms, which often damage commercial fish stocks. Studies
predict species invasion will be profound in the Arctic and Southern Oceans (Cheung et al., 2009). Indeed, together these changes
could result in a significant turnover of species of more than 60%
of present biodiversity. This has the potential to disrupt a range ofmarine ecosystem services including food provisioning.
Climate change will impact across all the four dimensions(availability, stability, access and utilization) of food security.
Availability of aquatic products will vary through changes in ecosystems, production, species distribution and habitats. Changes
will occur at regional and local levels in freshwater and marine
systems due to ecosystem shifts and changing aquaculture options, which depend on availability of key inputs. Production53Larimitchthys polyactis catchin early 2000s...

North Korea

South Korea

China

Ryokyo Iss.
Diaoyutai Iss.

Japan

Figure 22: (a) Current (early 2000s) and (b) climate-shifted distributions of the small yellow
croaker Larimichthys polyactis (Sciaenidae). The
climate-shifted distribution was predicted by adynamic bioclimate envelope model describedby Cheung et al. (2008), under a hypotheticalincrease in average global ocean temperature of
2.5°C. Boundaries of Exclusive Economic Zones
are delineated by the dashed lines.

Taiwan...and predicted
catch shift

North Korea

South Korea

Japan

China

Ryokyo Iss.
Diaoyutai Iss.
Taiwan54

Tonnes0

200 500 900 1400 1600 or more

Sources: Cheung, W., C., et al., 2008.

from aquatic resources, whether through fisheries or aquaculture, may be impacted by the adaptive capacity of management
measures controlling temporal and spatial access.

directly hamper people’s access to food by constraining individuals’ expression of their entitlements and rights to food.

Stability of supply will be impacted by changes in seasonality,
increased variance of ecosystem productivity, increased supply
risks and reduced supply predictability – issues that may also
have large impacts on supply chain costs and their flexibility torespond to variation.

Utilization of nutrients (i.e. their nutritional value) from fisheryproducts will be affected through changing supply quality andmarket chain disruptions. In some cases, a period of adjustment will be required to move to species that are not traditionally consumed. These issues are most critical for countries witha high per capita consumption of aquatic proteins.

Access to fish for food will be affected by changes in the distribution of fish species and in livelihoods combined with transferred
impacts from other sectors (increases in prices of substitute foodproducts), competition for supply, and information asymmetries.
Policies and measures tackling climate change impacts may in-Harmful algal blooms (HABs), which affect fisheries, and insome cases result in making shellfish and finfish toxic to humans
are expected to vary in frequency, distribution and timing withclimate change. HABs are primarily composed of dinoflagellates(algae/phytoplankton) that can swim up and down the water col-Species turnover
Figure 23.

Biodiversity impact intensity
0 0.30 0.60 1.20 1.80 4.00 or more

Change in the initial species richness in2005 relative to 2001-2005 average(high-range climate change scenario)

Source: redrawn from Cheung W.W.L. et al., 2009.

55

be felt through changes in capture, production and marketingcosts, changes in sales prices and possible increases in risks ofdamage or loss of infrastructure, fishing and aquaculture tools
and housing. Fishery-dependent communities may also face
increased vulnerability in terms of less stable livelihoods, decreases in availability and/or quality of fish for food, and safety
risks, for example, fishing in harsher weather conditions andfurther from their landing sites.

umn. It is predicted that when oceanic waters become more stratified, these algae are expected to survive better than other phytoplankton, and therefore the frequency of harmful algal bloom
events could increase (Moore et al., 2008). Their range is expected
to extend to higher latitudes as sea temperatures rise due to climate change. HABs have already been observed more frequently
in northern Europe (Tester, 1994). The timing and duration of
HAB events is also predicted to change as sea temperatures willreach their maximum earlier and for longer periods of time, with
optimal growing conditions lasting longer (Moore et al., 2008).
These combined changes will expose more people for longer time
periods and over wider geographic ranges to the toxins associatedwith harmful algal blooms either as aerosols or as accumulationsin shellfish and finfish (Moore et al., 2008).

WHO ARE THE MOST VULNERABLE TO
CLIMATE CHANGE IMPACTS ON OCEANS?

As mentioned in the previous chapters, impacts on the oceansfrom growing climate change are likely to include rising sea
levels, increasing acidity, increasing frequency and intensity of
extreme weather events, and decline in fisheries. The impacts ofthese physical and biological changes on fisheries and aquaculture communities will be as varied as the changes themselves(FAO, 2008; Cochrane et al., 2009). Both negative and positive impacts could be foreseen, their strength depending on thevulnerability of each community; combining potential impacts(sensitivity and exposure) and adaptive capacity. Impacts would
56

Impacts on aquaculture could also be positive or negative, arising from direct and indirect impacts on the natural resources
they require, primarily water, land, seed, feed and energy. As
fisheries provide significant feed and seed inputs, the impacts ofclimate change on them will also, in turn, affect the productivity
and profitability of aquaculture systems, thus jeopardizing foodsecurity (Cochrane et al., 2009). Vulnerability of aquaculturebased communities will stem from their resource dependency
and also on their exposure to extreme weather events. Climaticchanges could increase physiological stress on cultured stock,which would not only affect productivity but also increase vulnerability to diseases, in turn imposing higher risks and reducing
returns to farmers. Interactions between fisheries and aquaculture sub-sectors could create other impacts, for example extreme
weather events resulting in escapes of farmed stock and contributing to potential reductions in genetic diversity of the wild stock
and affecting marine biodiversity and ecosystems more widely.
These impacts will be combined with other aspects affecting
adaptive capabilities, such as the increased pressure that everlarger coastal populations place on resources, any political, institutional and management rigidity that negatively impacts oncommunities’ adaptive strategies, deficiencies in monitoringand early-warning systems or in emergency and risk planning,as well as other non-climate factors such as poverty, inequality,
food insecurity, conflict, and disease.
The degradation of these marine ecosystems by climate change,
poor coastal waste management, as well as from unsustainable
natural resource extraction practices including bottom trawling(UNEP, 2008b), will impact a broad range of aspects of foodand livelihoods security. Adaptation and mitigation to ensure
improved integrated coastal and aquatic resource management
is therefore essential both for restoring carbon sink capacity, as
well as for health, livelihoods, incomes and food security.

Vulnerability of national economies to potential
climate-induced changes in fisheries
High

Figure 24: Comparative vulnerability of national economies to climate impacts on fisheries. Vulnerability of national economies ofpotential climate change impacts on fisheries (which integrates exposure, sensitivity
and adaptive capacity) under IPCC scenario
B2 (local development, lower emissions).

Moderate
Low
Very low
No data available

19 of the 33 countries included in the High Vulnerability class are Least Developed Countries.
For some of the most strongly fishery dependent countries (Benin, Chad, Comoros, Maldives,
the Republic of Korea, São Tomé and Principe) vulnerability data are not available.
Source: E. H. Allison et al, Vulnerability of national economies to the impacts of climate changes on fisheries, Fish and Fisheries, 2009, 10, pp. 173-196.

The vulnerability of national economies to potential climate change impacts on fisheries was calculated combining composite indicators that evaluate the adaptive capacity of countries,
their exposure to climate change and their fisheries dependence.
The adaptive capacity indicator is calculated from indexes of health, education, governance and size of economy.
The country-specific mean surface temperature increase by 2050 for IPCC scenario B2 (local development, lower emissions) was considered as indicator of exposure to climate change.
The indicator of fisheries dependence was deduced from the national number of fishers (absolute and relative to the labour force) and landings, the income dependency on fisheries-derived
exports and per capita fish proteins as a proportion of total animal proteins consumed.

57

58

59

Recognizing that healthy and productive coastal
ecosystems, already increasingly stressed by land-basedsources of pollution, coastal development, and habitat
destruction, have a growing role in mitigating theeffects of climate change on coastal communities andeconomies in the near term…
We stress the need for sustainable management ofcoastal and marine ecosystems, including mangrove,
wetland, seagrass, and coral reefs, as protective andproductive buffer zones that deliver valuable ecosystem
goods and services that have significant potential for
addressing the adverse effects of climate change.
The Manado Declaration (WOC, 2009).

60

ECOSYSTEM-BASED ADAPTATION
AND MITIGATION
There is increasing awareness and evidence of the potential of restoring natural eco­systems as a way to mitigate climate change, but also ensuring the continued flow of
ecosystem services (MA, 2005; Trumper et al., 2009). These services, including, but notlimited to, extreme weather and tsunami buffering effects, enhanced food supply, pollu­
tion mitigation and health issues, are mainly concentrated in the coastal zone of oceans(UNEP, 2006; 2008b). Indeed, oceans blue carbon sinks, along with coral reefs and kelp
communities, all fulfil very important functions in the coastal zone while providing op­
portunities for jobs and coastal prosperity.
Unfortunately, blue carbon sinks are disappearing at an
alarming rate. Human activities such as deforestation, pollution by nutrients and chemicals from agricultural and industrial runoff, unsustainable coastal development, overfishing, invasive species infestations, oil spills, dredging, fillingor drainage that cause sediment-loading, mining, and loss of
biodiversity are impacting coastal ecosystems worldwide, far
exceeding the natural buffering capacity of these ecosystems(UNEP, 2006; 2008b).

MANAGEMENT OF BLUE CARBON SINKSAND THEIR RESTORATIONBlue carbon sinks are hot spots for carbon burial in the ocean
where they play a globally significant role that needs be incorporated into current inventories of natural carbon sinks. Abouthalf of their sink capacity may have been lost already, mainly
through the loss of these vegetated coastal habitats since the1940s. Efforts to recover the capacity of blue carbon sinks
needs be incorporated in current strategies to mitigate climatechange, thus providing an impetus for restoration efforts. The
recovery of blue carbon sinks will help countries mitigate theircarbon emissions while restoring valuable ecosystem services
and key natural resources. Integrated coastal management will
become central in this process to ensure both the carbon binding capacity and the goods and services rendered for food security, coastal livelihoods and sustainable coastal development.

There is sufficient evidence that reversing the global decline ofvegetated coastal habitats and recovering the lost area of blue carbon sinks would provide a very large improvement in the ecological status of the global coastal environment. This could result in
the recovery of important services, such as their capacity to oxygenate coastal waters, serve as nurseries, helping restore world
fish stocks, or shelter the shoreline from storms and extreme
weather events (Hemminga and Duarte 2000; Danielsen et al.,2005). At the same time by stopping the loss and degradation, we
would rebuild an important natural carbon sink, thereby contributing to mitigating CO2 emissions and, hence, climate change.
Because blue carbon sinks occur along the shorelines of allcontinents, except the Antarctic, states in regions with extensive shallow coastal areas across the world (e.g. India, south
east Asia, Black Sea, West Africa, Caribbean, Mediterranean,eastern USA, Russia) could explore the potential to mitigate
CO2 emissions and improve their coastal resources by protecting and restoring their blue carbon sinks. Expanding blue
carbon sinks is, therefore, a win-win strategy, (comparable tostrategies in place to protect and rebuild the carbon sink capacity of rainforests) which, helps to address the commitments ofstates under both the Biological Diversity and Climate Change
Conventions of the UN. For instance, the ongoing national wetland conservation action plan in China has been estimated to
involve a potential for increased carbon sequestration by 6.57
61

Gg C year–1 (Xiaonana et al., 2008). Andrews et al. (2008) calculated that the net effect of returning of returning some 26
sq km of reclaimed land in the UK to intertidal environments
could result in the burial of about 800 t C year−1.
A first step is the protection of these important blue carbon sinkhabitats, already in place in many countries (e.g. EU members,
USA, among others). This involves the regulation of activities
responsible for their global loss, including coastal reclamation,
deforestation of mangrove forests, excess fertilizer applicationon land crops and inputs of urban organic waste, siltation derived from deforestation on land, unsustainable fishing and fixing of coastlines through coastal development (Duarte, 2002;2009). Best practices for the management of blue carbon sinks
are available to help maintain these ecosystems healthy while
preserving their functions (e.g. Borum et al., 2004; Hamilton
and Snedaker 1984; Melana et al., 2000).
A second step should involve efforts for the large-scale restoration of the lost area, which is probably of the same order(if not larger) than the area currently still covered by these62

aquatic habitats (Duarte 2009; Waycott et al., 2009). For instance, some countries in SE Asia have lost almost 90% of
their mangroves since the 1940s (Valiela et al., 2001). Largescale restoration projects have been successfully conducted for
mangroves. The single largest effort probably being the afforestation of the Mekong Delta forest in Vietnam, completely destroyed by the use of Agent Orange in the 1970’s and replanted by the Vietnamese people (Arnaud-Haond et al., in press).
Salt-marsh restoration is also possible and has been appliedlargely in Europe and the USA (e.g. Boorman and Hazelden
1995). Restoring lost seagrass meadows is more complex, as
the labour required to insert transplants under the water increases cost. Seagrass restoration projects have consequently
remained comparatively limited in size (a few hectares) andnumber. However it is a viable option provided the benefits ofseagrass restoration can be used strategically, for example tocatalyze the great potential for natural recovery. This is a slow
process when unassisted (Duarte et al., 2005b), so has to besupported in parallel with actions to remove the pressures thatcaused the loss in the first place. Such efforts would provide
initial sources of growth and subsequently benefit from theexponential capacity of seagrass meadows to expand, throughthe growth of their rhizomes, over the seafloor. While green forest can only grow upwards, seagrasses can spread horizontallyat exponential rates.
The sequestration capacity of individual marine ecosystems varies substantially (Table 1). Not all blue carbon sinks are equallyeffective, with salt marshes having the highest carbon burial rate
per unit area, followed by mangroves and seagrass. Our current
understanding of what drives a high capacity for blue carbon
sink ecosystems includes high biomass and production, where
the plants produce large surplus of organic carbon (Duarte andCebrián, 1996), and their location in an area where land-basedmaterials can be intercepted, adding to the self-derived surplus
to result in large carbon burial rates (Bouillon et al., 2008). Restoration efforts must focus on the recovery of blue carbon sinks
with high sequestration capacity, considering these drivers andcatalyzing the capacity of these ecosystems to act as efficient carbon sinks. Additional research on the conditions that result inhigh carbon sink capacity of vegetated coastal habitats can help
guide successful restoration projects.
Most efforts to restore blue carbon sinks have been driven by theneed to restore coastal protection by vegetated habitats and theirvalue as habitats for key species (Boorman and Hazelden, 1995;
Fonseca et al., 2000; Danielsen et al., 2005). It is time that theirbeneficial role as carbon sinks is also taken into account and toinclude this in economic assessments of the benefits of restoring blue carbon sinks.

INTEGRATED ECOSYSTEM APPROACHES

Improving the resilience of the coastal and oceans communities,
both human and aquatic, to the impacts of climate change will
be key to sustaining the role of the oceans as providers of foodand livelihood security. Comprehensive and integrated ecosystem approaches to managing coasts, oceans, and uses of aquatic
resources should form the basis for climate change adaptationand mitigation strategies as they address the social, economic,
ecological and governance aspects underlying vulnerability to
climate change. Such integrated approaches would help to link
the multiple sectors depending on coastal and ocean resources tothose organizations with climate change and disaster risk management responsibilities; thereby assisting in climate proofing
sector-specific development strategies as well as ‘mainstreaming’
the aquatic-based sectors into climate change strategies.

The management of coastal carbon sinks –a forthcoming IUCN/Natural England/UNEP report
The issue of marine carbon sequestration is attracting growing attention globally, and a new collaborative report titled ‘The management ofcoastal carbon sinks’ by the International Union for the Conservationof Nature and Natural England, further examines the issue in closer
detail. This report documents the latest information from world-leading
scientists on the carbon management potential of a number of coastal
ecosystems: tidal salt marshes, mangroves, seagrass meadows, kelp
forests and coral reefs. It explores the latest science for each ecosystem,
explores their role in the carbon cycle, and outlines management options that would maintain and enhance the carbon sinking capability ofeach ecosystem. This report is planned released later this year (2009).

As is the case in land-based sectors, many mutually reinforcing synergies and benefits exist among mitigation actions and overall development goals for coastal and ocean
resources. These benefits include, for example, improved
fisheries and aquaculture production systems, biodiversity
conservation through increasing mangrove populations, andincreased energy efficiency in the shipping sectors. Efforts
should include areas of mutual benefit to food and livelihood
security and the responsibilities of these sectors to reduceand avoid emissions as well as to enhance natural removalsof greenhouse gases.
In order to avoid negative trade-offs between adaptationand mitigation within and among sectors, an ecosystemapproach and system-wide evaluation and planning of mitigation and adaptation strategies will need to include downstream impacts on other sectors. It is very clear from thisreport, that the carbon sink capacity of these valuable coastal
ecosystems should provide massive additional impetus for
improved integrated coastal zone management, protection
and restoration.
63

64

POLICY OPTIONSIn the discussions on climate change, marine ecosystems have not received sufficientattention considering their importance for both mitigation and adaptation. A major con­tributing factor has been the complexity of marine ecosystems, their status as an interna­
tional and common property resource, and the absence of robust mitigation metrics.

While numerous technical issues await full scientific and political consensus, international climate change instruments needto remain open to the development of agreed mechanisms andmeasures which support marine ecosystem coherence and resilience and build on the strong synergies between mitigation
and adaptation.
Marine ecosystems have, until very recently, been vastly overlooked in climate change mitigation and adaptation debates. Today’s economies are mainly based on burning of fossil fuels. For
many countries, there will be major challenges in developing
industry and expanding transport while reducing emissions. It
is absolutely critical that while emission reductions of brownand black carbon are made, we must also maintain, and expand,the ability of the biosphere, and in particular the oceans, to continue to capture and bind the carbon that we emit. There is anurgent need for new ways to reduce the impact of continuingemissions, not just by adapting, but also by ensuring that asmuch carbon as possible is taken up by the natural system – andstored. Oceans have acted as one of the largest natural carbon
sinks throughout history and their ability to continue this roleshould be enhanced. A word of caution is, however, warranted:
there is no ‘golden key’ to solve all problems. New innovate
short-term solutions, including geo-engineering options such as
fertilizing the oceans or pumping CO2 into the deep seas raise
serious ecological, economic, political and ethical challenges,

with many unknown variables and high risk of potential side effects (see Factbox 5). These proposals should not be dismissed,
but before being operationalized on a large or commercial scale,more research and careful, thorough evaluation is required.
Options that can both reduce and mitigate climate change, increase food security, benefit health and subsequent productivity and generate jobs and business are therefore of major importance. This is contrary to the perception that mitigation oremission reduction is seen as a cost and not an investment. Improved integrated management of the coastal and marine environments, including protection and restoration of our ocean’s
blue carbon sinks, provides one of the strongest win-win mitigation efforts known today. It may provide value-added benefits
well in excess of its cost, but has not yet been recognized in the
global protocols and carbon trading systems.
Blue carbon sinks cover only a fraction of the world’s oceans– and yet are critical and among the most effective carbon
sinks known today. They provide valuable ecosystem services
for fisheries, tourism and coastal economies. But they are disappearing at a rate higher than any other ecosystem on earth.
Less than two decades remain to secure them and restore them,with immediate carbon-binding effect and immediate returns
in terms of fisheries and added benefits from improved shoreline protection and ecosystem services.
65

66

67

Fact box 8. A 25% emission reduction could be gained from green and blue carbon
The most recent estimates indicate that human activities are currently responsible for annual global carbon emissions of around
7–10,000 Tg C yr–1, of which around 1,500 Tg C or around 15–
20% is the result of land use change. The remaining emissions
are from fossil fuel use and cement production (Canadell et al.,2007). This has led to an average annual rate of increase of CO2
concentrations in the atmosphere of 1–2 ppm or up to 2,000 Tg C
yr–1 for the years 1995–2005 compared with around 1.25 ppm forthe years 1960–1995 (IPCC, 2007b; Houghton, 2007).
Green carbon: Reducing deforestation rates by 50% by 2050
and then maintaining them at this level until 2100 would avoid
the direct release of up to 50 Gt C this century or approximately
555 Tg C yr–1, which is equivalent to 12–15% of the emissions

68

reductions needed to keep atmospheric concentrations of carbon
dioxide below 450 ppm (Trumper et al., 2009).
Blue carbon: According to this report, protection, improved management and restoration of the ocean’s blue carbon sinks would
result in preventing the annual loss of up to 450 Tg C yr–1, or equivalent to a corresponding 10% of the reductions needed.
Combined with the green carbon – REDD – the effect would be atleast 20–25% of the emission reductions needed – with huge benefits to food security, water resources, biodiversity – and the creation of jobs and incomes. But this would require a similar “REDD”
programme for oceans as has been established for rainforests – ablue carbon fund.

KEY OPTIONS:In order to implement a process and manage the necessary funds for the protection,
management and restoration of these crucial ocean carbon sinks, the following options
are proposed:

Establish a global blue carbon fund for protection
and management of coastal and marine ecosystems and ocean carbon sequestration.
a. Within international climate change policy instruments, create mechanisms to allow the future use of carbon credits formarine and coastal ecosystem carbon capture and effective storage as acceptable metrics become available. Blue carbon could
be traded and handled in a similar way to green carbon – suchas rainforests – and entered into emission and climate mitigation protocols along with other carbon-binding ecosystems;
b. Establish baselines and metrics for future environmentallysound ocean carbon capture and sequestration;c. Consider the establishment of enhanced coordination andfunding mechanisms;
d. Upscale and prioritize sustainable, integrated and ecosystem-based coastal zone planning and management, especiallyin hotspots within the vicinity of blue carbon sinks to increase
the resilience of these natural systems and maintain food andlivelihood security from the oceans.

1

Immediately and urgently protect at least 80% of
remaining seagrass meadows, salt marshes andmangrove forests, through effective management.
Future funds for carbon sequestration can contribute to maintaining management and enforcement.

2

3

Initiate management practices that reduce and remove threats, and which support the robust recovery
potential inherent in blue carbon sink communities.

Maintain food and livelihood security from theoceans by implementing comprehensive and integrated ecosystem approaches aiming to increase
the resilience of human and natural systems to change.

4

Implement win-win mitigation strategies in theocean-based sectors, including to:a. Improve energy efficiency in marine transport, fishing and aquaculture sectors as well as marine-based tourism;
b. Encourage sustainable, environmentally sound ocean basedenergy production, including algae and seaweed;c. Curtail activities that negatively impact the ocean’s ability toabsorb carbon;
d. Ensure that investment for restoring and protecting the capacity of ocean’s blue carbon sinks to bind carbon and provide
food and incomes is prioritized in a manner that also promotes
business, jobs and coastal development opportunities;
e. Catalyze the natural capacity of blue carbon sinks to regenerate by managing coastal ecosystems for conditions conducive
to rapid growth and expansion of seagrass, mangroves, and salt
marshes.

569

GLOSSARY
Acidification
See Ocean acidification.

Carbon sink
See Sink.

Afforestation
Afforestation is defined under the Kyoto Protocol as the direct
human-induced conversion of non-forest land to permanent forested land (for a period of at least 50 years) (Angelsen 2008).

Carbon source
See Source.

Archaea
Unique, single celled organisms which are genetically and metabolically distinct from bacteria.
Autotrophic
Of or relating to an autotroph, an organism capable of making
nutritive organic molecules from inorganic sources via photosynthesis (involving light energy) or chemosynthesis (involving
chemical energy).
BiofuelAny liquid, gaseous, or solid fuel produced from plant or animal organic matter. e.g. soybean oil, alcohol from fermented
sugar, black liquor from the paper manufacturing process,wood as fuel, etc. Second-generation biofuels are products suchas ethanol and biodiesel derived from ligno-cellulosic biomassby chemical or biological processes (IPCC 2007a).

Clean Development Mechanism (CDM)
A mechanism under the Kyoto Protocol designed to assist developed (Annex I) countries in meeting their emissions reduction targets. The mechanism reduces emissions through implementing projects in developing (Annex II) countries which arecredited to the Annex I countries who finance and implement
the project. The CDM aims to not only reduce emissions or increase sinks but also contribute to the sustainable developmentof the host country (Peskett et al. 2008).
Greenhouse gases
Greenhouse gases are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit
radiation at specific wavelengths within the spectrum of infrared radiation emitted by the earth’s surface, the atmosphereand clouds. This property causes the greenhouse effect. Water
vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and ozone (O3) are the primary greenhouse gases inthe earth’s atmosphere (IPCC 2007a).

Carbon cycle
The term used to describe the flow of carbon (in various forms,
e.g., as carbon dioxide) through the atmosphere, ocean, terrestrial biosphere and lithosphere (IPCC 2007c).

Kyoto Protocol
An agreement made under the United Nations Framework
Convention on Climate Change (UNFCCC). Countries that
ratify this protocol commit to reducing their emissions of carbon dioxide and five other greenhouse gases (GHG), or engaging in emissions trading if they maintain or increase emissions of these gases. The Kyoto Protocol now covers more than170 countries globally but only 60% of countries in terms ofglobal greenhouse gas emissions. As of December 2007, theUS and Kazakhstan are the only signatory nations not to have
ratified the act. The first commitment period of the Kyoto Protocol ends in 2012, and international talks began in May 2007
on a subsequent commitment period (Peskett et al. 2008).

Carbon sequestration
The process of increasing the carbon content of a reservoir
other than the atmosphere (Chopra et al. 2005).

Land Use, Land Use Change and Forestry (LULUCF)
A greenhouse gas inventory sector that covers emissions andremovals of greenhouse gases resulting from direct human-

Coastal ocean
The region extending from the beaches out across the continental shelf, slope, and rise (Brink, 1993).
Carbon Capture and Storage (CCS)
A process consisting of separation of CO2 from industrial andenergy-related sources, transport to a storage location, andlongterm isolation from the atmosphere (IPCC, 2007a).

70

induced land use, land-use change and forestry activities (UNFCCC 2009).
Leakage
In the context of climate change, carbon leakage is the resultof interventions to reduce emissions in one geographical area
(subnational or national) that lead to an increase in emissions
in another area. For example, if curbing the encroachment ofagriculture into forests in one region results in conversion offorests to agriculture in another region this is considered to be“leakage”. In the context of REDD, leakage is also referred to as‘emissions displacement’ (Angelsen 2008).
Mitigation
A human intervention to reduce the sources of or enhance the sinks
for greenhouse gases (Department of Climate Change 2008).
Ocean acidification
A decrease in the pH of sea water due to the uptake of anthropogenic carbon dioxide (IPCC 2007c).
Open ocean
Where the water depth exceeds 200m around the boundariesof the major continental land masses. This definition excludes
the marginal enclosed and semi-enclosed seas, but includes all
ocean regions bordering lesser island systems regardless of water depth (UNEP and IOC-UNESCO, 2009).
Permanence
The duration and non-reversibility of a reduction in GHG emissions (Angelsen 2008). This is an issue in the land use sector as carbon stored and sequestered in ecosystems is theoretically always
vulnerable to release at some undetermined point in the future.
Reforestation
Reforestation is “the direct human-induced conversion of nonforested land to forested land through planting, seeding and/or
the human-induced promotion of natural seed sources, on landthat was forested, but that has been converted to non-forested
land”. In the first commitment period of the Kyoto Protocol, reforestation activities have been defined as reforestation of lands
that were not forested on 31 December 1989, but have had forest
cover at some point during the past 50 years (Angelsen 2008).

Respiration
The process whereby living organisms convert organic matterto carbon dioxide, releasing energy and consuming molecularoxygen (IPCC 2007c).
Sequestration
The removal of atmospheric carbon dioxide, either throughbiological processes (for example, photosynthesis in plants
and trees, see Biosequestration), or geological processes (forexample, storage of carbon dioxide in underground reservoirs)(Department of Climate Change 2008).
Sink
Any process, activity or mechanism that removes a greenhousegas, an aerosol or a precursor of a greenhouse gas or aerosol
from the atmosphere (IPCC 2007c).
SourceAny process, activity or mechanism that releases a greenhousegas, an aerosol or a precursor of a greenhouse gas or aerosol
into the atmosphere (IPCC 2007c).
Sustainability
A characteristic or state whereby the needs of the present andlocal population can be met without compromising the abilityof future generations or populations in other locations to meettheir needs (Chopra et al. 2005).
United Nations Framework Convention on Climate
Change (UNFCCC)The United Nations Framework Convention on Climate
Change (UNFCCC) is the first international climate treaty.
It came into force in 1994 and has since been ratified by 189
countries including the United States. More recently, a numberof nations have approved an addition to the treaty: the Kyoto
Protocol, which has more powerful (and legally binding) measures (Kirby 2008).
UNFCCCSee United Nations Framework Convention on Climate Change.

71

ACRONYMS
CCDM
CO2EU-ETS
FAO
GEF
GHG
GRID
HAB
HCO3–
HCl
MEDEA
IPCC
°C
ppm
REDD
REDD-PlusSIDS
SOC
T C yr–1
Tg C yr–1
UNEP
UNEP-WCMCUNESCOIOC-UNESCO
USA
USD
yr–1

CarbonClean Development Mechanism
Carbon dioxide
The Emissions Trading System of the European Union
Food and Agriculture Organization of the UN
Global Environment Facility
Green house gas
Global Resource Information DatabaseHarmful Algal Bloom
Bicarbonate ion
Hydrochloric acid
Mediterranean Institute of Advanced Studies
Intergovernmental Panel on Climate Change
Degrees centigrade
Parts per million
United Nations Collaborative Programme on Reducing Emissions from
Deforestation and Forest Degradation in Developing Countries
Reducing emissions from deforestation and degradation, conservation ofexisting carbon stocks and enhancement of carbon stocks
Small Island Developing States
Sedimentary organic carbon
Tonnes of carbon per year
Tera grams of carbon per year
United Nations Environment Programme
UNEP-World Conservation Monitoring Centre
United Nations Educational, Scientific and Cultural Organisation
Intergovernmental Oceanographic Commission of UNESCO
United States of America
US Dollars
per year

PHOTO CREDITS
1 iStockphoto/Felix Möckel 1 iStockphoto/Nicholas Monu 4 iStockphoto/Jan Rysavy 9 iStockphoto/Andriy Myahkov 10 iStockphoto/Judson
Abts 14 iStockphoto/Susanna Pershern 18–19 Manu San Felix 20 iStockphoto/Keiichi Hiki 20 iStockphoto/David Parsons 20 iStockphoto/
JurgaR 20–21 iStockphoto/Tammy Peluso 28 iStockphoto/John Kounadeas 29 iStockphoto/thp73 34 iStockphoto/Sharon Metson 38–39
Carlos M. Duarte 40 iStockphoto/Jarosław Juszkiewicz 44 iStockphoto/Haider Yousuf 48 iStockphoto/Suzana Profeta 49 Jacqueline Alder
50 iStockphoto/brytta 53 iStockphoto/Rainforest Agencies 56 iStockphoto/Thomas Bradford 58–59 OCEANA/Juan Cuetos 59 OCEANA/Mar
Mas 59 OCEANA/Juan Cuetos 60 iStockphoto/jacus 62 iStockphoto/Lesley Jacques 63 iStockphoto/Omar Ariff 64 Jennifer Wolf/WolfHartt
Image/Marine Photobank 66 Topham Picturepoint/UNEP/David Tapia Munoz 66 iStockphoto/Sergey Dubrovskiy 66 iStockphoto/Antonio
D’Albore 67 iStockphoto/Serdar Yagci 67 iStockphoto/Galina Barskaya 67 iStockphoto/pidjoe 68 Moh Nur Harun/Marine Photobank 79
iStockphoto/Maria Pavlova 80 iStockphoto/Valentin Casarsa
72

CONTRIBUTORS AND REVIEWERSEDITORS
Christian Nellemann, Emily Corcoran, Carlos M. Duarte, Luis Valdés, Cassandra De Young, Luciano Fonseca, Gabriel Grimsditch

CARTOGRAPHY
Riccardo Pravettoni
Giulio Frigieri (Figures 6 and 24)

CONTRIBUTORS
Tarub Bahri
Food and Agriculture Organisation of the United Nations, Vialedelle Terme di Caracalla, 00153 Roma, Italia

REVIEWERS
Elaine Baker, Jean-Nicolas Poussart, Morten Sørensen
UNEP/ GRID-Arendal, Teaterplassen 3, 4836 Arendal, Norway,
www.grida.no

Carlos M. Duarte
Department of Global Change Research. IMEDEA (CSIC-UIB)
Institut Mediterráni d’Estudis Avançats, Miquel Marqués 21, Esporles, Spain

Rob Kay
Coastal Zone Management (Australia) Pty Ltd, PO Box 436, Claremont, Perth, Australia, 6010

Cassandra De Young, Doris Soto
Food and Agriculture Organisation of the United Nations, Vialedelle Terme di Caracalla, 00153 Roma, Italia
Christian Nellemann, Emily Corcoran, Riccardo Pravettoni, Petter
Sevaldsen
UNEP/GRID-Arendal, Teaterplassen 3, 4836 Arendal, Norway,
www.grida.no
Jacqueline Alder, Ole Vestergaard, Gabriel Grimsditch
United Nations Environment Programme, Division for Environmental Policy Implemnentation, United Nations Avenue, Gigiri,
PO Box 30552, 00100 Nairobi, Kenya
Luis Valdés, Luciano Fonseca
Intergovernmental Oceanographic Commission of UNESCO, 1
rue Miollis, 75732 Paris Cedex 15, France
Nicole Glineur
Global Environment Facility, Biodiversity and Private Sector GEF
Secretariat, 1818 H Street, NW, MSN G6-602, Washington, DC
20433, USA
Pavan Sukhdev
Green Economy Initiative (UNEP), 219 Huntingdon Road, Cambridge, CB3 0DL, UK
Stefan Hain, Corinna Ravilious, Terri Young
UNEP World Conservation Monitoring Centre (UNEP-WCMC),
219 Huntingdon Road, Cambridge, CB3 0DL, UK
William Cheung
School of Environment Sciences, University of East Anglia Norwich, NR4 7TJ, UK
Carl-Gustaf Lundin
International Union for the Conservation of Nature (IUCN)
Global Marine Programme, Rue Mauverney 28, CH-1196 Gland,
Switzerland

Chris Tompkins
Independent Consultant
Richard Kenchington
RAC Marine Pty Ltd, P.O. Box 588, Jamison, ACT 2614, Australia
Kieran Kelleher
The World Bank, Washington D.C. 20433, USA
Francine Kershaw
UNEP World Conservation Monitoring Centre (UNEP-WCMC),
219 Huntingdon Road, Cambridge, CB3 0DL, UK
James Spurgeon,
Environmental Resources Management, Eaton House, WallbrookCourt, North Hinksey Lane, Oxford, OX2 0QS, UK
David Osbourne
United Nations Environment Programme, Division for Environmental Policy Implemnentation, United Nations Avenue, Gigiri,
PO Box 30552, 00100 Nairobi, Kenya
Gail M. Chmura
McGill University, Department of Geography, 805 Sherbrooke St
W, Montreal, QC H3A 2K6 Canada
Ingunn Vistnes
Norut Alta – Áltá, Postboks 1463, N-9506 Alta, Norway
COPY EDITORS
Ania Niedzwiadek, Carmen Elrickn
Coastal Zone Management, Pty Ltd, PO Box 436, Claremont, Perth,
Australia, 6910
Harry Forster
Interrelate, 2, rue Saint Laurent, 38000 Grenoble, France73

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