Source document: https://docs-lawep.s3.us-east-2.amazonaws.com/1694841067286.pdf (Mauritius)
Climate change science, current developments and what it means for Small Island Developing States Overview • Climate change science • Understanding climate change • Some local experiences/perspectives • Summary of implications for Small Island Developing States Global change Climate change Source: www.igbp.kva.se Source: FAQ 3.1, Figure 1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press Causes of Change The Greenhouse Effect Solar changes Volcanic eruptions Greenhouse gases Aerosols Land cover Potential Climate Change There are both natural and anthropogenic drivers of climate change.
There will always be natural variability superimposed on long-term trends.

Source: FAQ 1.3, Figure 1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press 1 The Climate System Understanding climate change • Paleoclimate history • On-going global observations • Climate models Source: FAQ 1.2, Figure 1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press Cenozoic Era Cenozoic Era compared to now 1.
Dominant Forcing: Natural ∆CO2 - Rate ~100 ppm/My (0.0001 ppm/year) - Human-made rate today: ~2 ppm/year Humans Overwhelm Slow Geologic Changes 2.

Climate Sensitivity High - Antarctic ice forms if CO2 < ~450 ppm - Ice sheet formation reversible Humans Could Produce “A Different Planet” 50 million years ago (50 MYA) Earth was ice-free.

Atmospheric CO2 amount was of the order of 1000 ppm 50 MYA.

Atmospheric CO2 imbalance due to plate tectonics ~ 10-4 ppm per year.
Source: Jim Hansen http://www.columbia.edu/~jeh1/ Source: Jim Hansen http://www.columbia.edu/~jeh1/ Vostok ice core records Climate shifts Earth’s history provides important information on global warming.

Recorded human history occurs within the Holocene warm period.
Source: Jim Hansen http://www.columbia.edu/~jeh1/ Source: Brian Fagan, The Long Summer: How Climate Changed Civilization, Basic Books, 2004 2 Holocene changes The carbon cycle Source: Brian Fagan, The Long Summer: How Climate Changed Civilization, Basic Books, 2004 Source: www.igbp.kva.se Carbons longest journey Human influence Source: Stephan Harding, Animate Earth: Science, Intuition and Gaia, Green Books, 2006 Global greenhouse gas emissions Global greenhouse gas emissions Source: Figure 2.1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press 3 Changes in Greenhouse Gases Globally, greenhouse gas concentrations are increasing Source: FAQ 2.1, Figure 1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press Carbon dioxide, ppm (CO2 379ppm, CH4 1780ppb, N2O 319ppb) • Present carbon dioxide concentrations highest for 650,000 years, likely 20 My.
• Since 1750 - carbon dioxide increase 35% - methane increase 150% - Nitrous oxide increase 18% • Human activities emit annually ~7,000,000,000 tonnes of carbon dioxide • About half of this stays in the atmosphere … and increasing Radiative Forcing Canadian Tarsands, Source: National Geographic Source: FAQ 2.1, Figure 2, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press Buzz groups (5 mins) Observed climate changes • What are the key messages from the presentation so far?
Source: Figure 1-1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press 4 Consistency of observations • Surface temperatures increasing • Atmospheric water vapour content increasing • Ocean heat content increasing … • … now directly linked to sea level rise • Greenland and Antarctic Ice Sheets losing mass • Glaciers and snow cover declined • Arctic sea ice extent decreasing • More intense and longer droughts • More frequent heavy precipitation events over land • Tropical cyclone intensity increasing (North Atlantic) ARGO http://www.argo.ucsd.edu What is Argo?
Argo is a global array of 3,000 free-drifting profiling floats that measures the temperature and salinity of the upper 2000m of the ocean.

ARGO data Arctic sea ice area at warm season minimum Knowledge of Earth’s energy imbalance is improving rapidly as ARGO data lengthens.

Data source: von Schuckmann et al.

J. Geophys.

Res.
114, C09007, 2009, doi:10.1029/2008JC005237 September sea ice extent based on satellite microwave observations Data source: National Snow and Ice Data Center Greenland total melt area ) 2 m k 6 0 1 ( a e r A t l e M l a t o T 35 30 25 20 15 10 5 1978 1983 1988 1993 Year 1998 2003 2008 Source: Jim Hansen http://www.columbia.edu/~jeh1/ Graph credit: Konrad Steffen, Univ.
Colorado Surface Melt on Greenland Melt descending into a moulin, a vertical shaft carrying water to ice sheet base.

Source: Roger Braithwaite, University of Manchester (UK) 5 Jakobshavn Ice Stream in Greenland Gravity Satellite Ice Sheet Mass Measurements Discharge from major Greenland ice streams is accelerating markedly.

Source: Prof. Konrad Steffen, Univ.

of Colorado Greenland Ice Sheet Antarctic Ice Sheet Source: Velicogna, I. Geophys.

Res.

Lett., 36, L19503, doi:10.1029/2009GL040222, 2009.


Himalayan (Rongbuk) Glacier Positive feedback Rongbuk, the largest glacier on Mount Everest’s northern slopes, in 1968 (top) and 2007.

Glaciers are receding rapidly world-wide, including the Rockies, Andes, Alps, Himalayas.

Glaciers provide freshwater to rivers throughout the dry season and reduce spring flooding.

Photos: Chinese Academy of Sciences and Greenpeace/John Novis Source: Ice-albedo feedback process.

(June 2007).
(June 2007).

In UNEP/GRID-Arendal Maps and Graphics Library.

Retrieved July 6, 2011 from http://maps.grida.no/go/graphic/ice- albedo-feedback-process Sea level rise • IPCC 2007 projects 0.18 to 0.59 m sea level rise by 2100 • A further 0.1 to 0.2 m rise possible from increased ice sheet discharge • An even larger contribution from ice sheets cannot be ruled out The Arctic as a Messenger of Global Processes, May 2011 • “Arctic snow and ice are melting much faster than expected.
This warming has local and global consequences, especially for global sea level rise which is now expected to be greater than previously projected (0.9-1.6 m by 2100).” http://amap.no/Conferences/Conf2011/programme.html 6 Cities at risk from sea level rise Stresses on Coral Reefs Photo credit: Kevin Roland Coral Reef Fiji More drought More floods Special report: Catastrophic Special report: Catastrophic drought in the Amazon drought in the Amazon The Independent, 4/2/2011 The Independent, 4/2/2011 A widespread drought in the A widespread drought in the Amazon rainforest last year caused Amazon rainforest last year caused the "lungs of the world" to produce the "lungs of the world" to produce moremore carbon absorbed, potentially leading absorbed, potentially leading to a dangerous acceleration to a dangerous acceleration of global warming.
of global warming.

than they dioxide than they carbon dioxide The wrath of 2007: America's great drought, The Independent, 11/6/2007 America is facing its worst summer drought since the Dust Bowl years of the Great Depression.

Or perhaps worse still.
Ministers call emergency Ministers call emergency summit as drought looms summit as drought looms The Independent, 15/5/2011 One of the driest springs on record has sparked fears for agriculture and wildlife, while crews 'work to the point of exhaustion' to battle forest fires UN warns of severe food UN warns of severe food crisis in Horn of Africa crisis in Horn of Africa The Independent, 29/6/2011 The Independent, 29/6/2011 The worst drought in 60 years The worst drought in 60 years in the Horn of Africa has sparked in the Horn of Africa has sparked a severe food crisis and high a severe food crisis and high malnutrition rates, with parts of malnutrition rates, with parts of Kenya and Somalia experiencing Kenya and Somalia experiencing prepre--famine conditions, famine conditions, the UN said yesterday.


Record floods put 20,000 at risk The Independent, 21/6/2011 More than 40 miles of dykes are in danger of being breached in an eastern Chinese province where floods have caused $1.2bn in losses, authorities said yesterday, as the country neared a critical point in battling seasonal rains.
Flooding hits southern Thailand, The Independent, 2/11/2010 Thailand's prime minister today called flooding in the south that has displaced thousands of people "one of the worst natural calamities" to hit the country.

Residents flee ahead of Mississippi floods, The Independent, 9/5/2011 Residents of Memphis have begun to abandoning low-lying homes as the dangerously surging Mississippi River threatens to crest in coming days just shy of a 48.7ft record set by a devastating flood in 1937.
UN: Pakistan floods ravage lives of millions, The Independent, 3/8/2010 The worst floods in memory in Pakistan have devastated the lives of more than three million people, a UN spokesman said today while outrage over the unpopular government's response to its people's plight spreads.

Number of reported disasters Extreme weather link 'can no longer be ignored' Possible Causes: • Climate change • Increased exposure • Increased reporting Source: Number of Disasters per Year.

(2009).
(2009).

In UNEP/GRID-Arendal Maps and Graphics Library.

Retrieved July 6, 2011 from http://maps.grida.no/go/graphic/number-of-disasters-per-year.

Scientists are to end their 20-year reluctance to link climate change with extreme weather – the heavy storms, floods and droughts which often fill news bulletins – as part of a radical departure from a previous equivocal position that many now see as increasingly untenable.
The Independent, 1/7/2011 7 Buzz groups (5 mins) Reliability of climate models • What climate changes have you observed/experienced, or are aware of?

Source: FAQ 8.1, Figure 1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press Is warming due to natural variability?
IPCC Projections Source: FAQ 9.2, Figure 1, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press Source: Figure 3.2, IPCC Fourth Assessment Report, Climate Change 2007, Cambridge University Press Future warming in historical context Even a low ‘business as usual’ scenario would lead to rapid global warming and temperatures greater than at any time during human civilisation.
High, medium and low greenhouse gas scenarios for the future Thermometer measurements Different Northern Hemisphere temperature records for the last 1300 years C o s e e r g e D What’s in a number: 350ppm or 450ppm?
Source: Andy Reisinger Source: IPCC 8 Warming under medium emissions scenario: 2100 Warming under medium emissions scenario: long-term Setting policy targets 2 degrees warming as limit: now accepted by more than 130 countries, including the G8 and Major Economies Forum in 2009 part of Copenhagen Accord 0.5 1.5 2.5 3.5 4.5 5.5°C IPCC AR4, WGII, TS.4 warming in degrees Celsius above pre-industrial levels Concentration targets What concentration of GHGs gets us to 2°C?
• 450ppm CO2-equivalent concentrations result in warming of 2°C as the best estimate … • … but climate science is uncertain: 450ppm could result in warming between 1.4 and 3.1°C … • … so there is a roughly 50% chance that warming could exceed 2°C even if we stabilise concentrations at 450ppm Jim Hansen • Heads the NASA Goddard Institute for Space Studies in New York City • Since the late 1970s, he has focused his research on Earth's climate, especially human-made climate change • Designated by Time Magazine in 2006 as one of the 100 most influential people on Earth Jim Hansen’s assessment Assessment of Target CO2 Phenomenon 1.
Arctic Sea Ice 2.

Ice Sheets/Sea Level 3.

Shifting Climatic Zones 4.

Alpine Water Supplies 5.

Avoid Ocean Acidification Target CO2 (ppm) 300-350 300-350 300-350 300-350 300-350 Initial Target CO2 = 350* ppm *assumes CH4, O3, Black Soot decrease Jim Hansen’s assessment Local experiences Target CO2: < 350 ppm To preserve creation, the planet on which civilization developed A Buddhist Monk stands in front of the Everest Mountain in the Himalayan mountain range.
He holds an empty bucket, symbolizing the loss of water from the region.

The Pu Mai village depends on the water source from the Rongbuk Glacier Mount Everest (Qomolangma).

© Greenpeace / John Novis 9 Preeca Siri, Thailand Luu Chi Kien, Viet Nam He said he has heard about the global warming and climate change because he goes to many meetings about the environment.

But his village and himself work on environmental protection so he think that the cause of global warming is human beings.
The main reason for higher temperatures is the forest destruction and also because of the mining of coal.

Sonam Chhering Gurung, Nepal Alfredo, Italy When I was 10 or 12 years old the lake near the Gangapurna Glacier was very small, the glacier was a massive chunk of ice.

But now everything is gone.

The lake has enlarged massively.

The receding of the glacier is progressing leaving the bare rocks behind.

I want to believe that maybe for the generation for my son, maybe some change.
Maybe one day some change.

The human race is not stupid like that and maybe one day say ‘stop it’… and some change… What it means for SIDS • A 450ppm target gives a high chance of significant impacts on SIDS • Global sea-level rise of above 1m by 2100 is increasingly a possibility • More extreme events – Extreme rainfall – Extreme temperatures/drought 10