（Lead http://hydro.iis.u-tokyo.ac.jp/Authors for the 4th Assessment Report of the IPCC, WG II, Chapter 3 “Freshwater resources1and their management”）

1

Climate Change Adaptation inWater Sector – focusing on water environment

Taikan Oki
Institute of Industrial Science, The University of Tokyo
Second WEPA International Workshop, Tokyo, Japan, Feburary 23rd, 2011

http://hydro.iis.u-tokyo.ac.jp/（IPCC AR4,WGII, TS, 2007）2http://hydro.iis.u-tokyo.ac.jp/

3

Impacts of climate change
on freshwater resources (1)Temperature will increase:Snow melt runoff will be changed intiming and the peak volume
water supplies stored in glaciers andsnow cover are projected to decline
Water temperature will rise. Water
quality and aquatic ecosystem could bedeteriorated. （IPCC AR4, WGII, SPM, 2007）http://hydro.iis.u-tokyo.ac.jp/

Impacts ofclimatechangeonfreshwater
resources (2)4Freshwater
Recharge
Freshwaterlens
sea water

Freshwater

Sea level will rise: sea waterSea water
intrusion to
ground water
near coastal
regionsea waterhttp://hydro.iis.u-tokyo.ac.jp/

5

Coastal Mega Cities are Vulnerable（IPCC AR4, WGII, SPM, 2007）http://hydro.iis.u-tokyo.ac.jp/

6

Impacts of climate change
on freshwater resources (3) Hydrological cycle will be changed (“intensified”)
10-40% increase of available water resources at highlatitudes and in some wet tropical areas, and 10-30%
decrease over some dry regions at mid-latitudes andin the dry tropics（IPCC AR4, WGII, SPM, 2007）
Drought-affected areas will likely increase in extent.
will lead more frequent wildfire
Heavy precipitation events, which are very likely toincrease in frequency, will augment flood risk.
will increase soil erosion/sediment load

http://hydro.iis.u-tokyo.ac.jp/

7

Changes in Annual River Discharge---Ensemble Mean of 15 GCM results for IPCC AR4 ---Increase(A1B)

Decrease（IPCC AR4, WGII, 2007）http://hydro.iis.u-tokyo.ac.jp/

8

Impacts of climate change
on ecosystems (1) The resilience of many ecosystems (their abilityto adapt naturally) is likely to be exceeded by
2100 by an unprecedented combination ofchange in climate, associated disturbances (e.g.,flooding, drought, wildfire, insects, oceanacidification), and other global change drivers(e.g., land-use change, pollution, overexploitation of resources) (high confidence).
（IPCC AR4, WGII, TS, 2007）http://hydro.iis.u-tokyo.ac.jp/

9Impact of human activities on freshwater
resources and their management, with climatechange being only one of multiple pressures(IPCC AR4, WGII, Chapter 3, “Freshwater Resources and their Management”, 2006)http://hydro.iis.u-tokyo.ac.jp/

10

Impacts of climate change
on ecosystems (2) Roughly 20 to 30%(varying among regional biotas
from1% to 80%) of species assessed so far (in anunbiased sample) are likely to be at increasingly highrisk of extinction as global mean temperatures exceed 2
to 3°C above preindustrial levels (medium confidence).
 Substantial changes in structure and functioning ofterrestrial and marine ecosystems are very likely tooccur with a global warming of 2 to 3°C above preindustrial levels and associated increased atmospheric
CO2 (high confidence).
（IPCC AR4, WGII, TS, 2007）http://hydro.iis.u-tokyo.ac.jp/11

http://hydro.iis.u-tokyo.ac.jp/

12

Impacts of climate change
on ecosystems related to water (3a)
 The following ecosystems are identified as mostvulnerable, and are virtually certain toexperience the most severe ecological impacts,
including species extinctions and major biomechanges. On continents: tundra, boreal forest,
mountain and Mediterranean-type ecosystems.
Along coasts: mangroves and salt marshes. And
in oceans: coral reefs and the sea-ice biomes.
（IPCC AR4, WGII, TS, 2007）http://hydro.iis.u-tokyo.ac.jp/

13

Impacts of climate change
on ecosystems related to water (3b)
 Initially positive ecological impacts, such as increased
net primary productivity (NPP), will occur inecosystems identified as least vulnerable: savannas andspecies-poor deserts. However, these positive effects arecontingent on sustained CO2-fertilisation, and only
moderate changes in disturbance regimes (e.g., wildfire)
and in extreme events (e.g., drought).
 As sea-ice biomes shrink, dependent polar species,
including predators such as penguins, seals and polar
bears, are very likely to experience habitat degradationand losses.
（IPCC AR4, WGII, TS, 2007）http://hydro.iis.u-tokyo.ac.jp/

14Japan Pavilion of EXPO Zaragoza (Spain)
Main Theme: Water and Sustainable Development
Changes in the
Occurrence ofExtreme
Events inRiver
Discharge

Movie

Hirabayashi et al., (HSJ, 2008)
Based on CCSR-NIES AOGCM

http://hydro.iis.u-tokyo.ac.jp/

15

Expected Annual
Maximum Daily Rainfall in X year return period
X年確率降水量（年最大日降水量）
100

20C
21C

日降水量(mm/day)
Daily
Rainfall (mm/day)

95

94.8

90

89.2

85

84.1

80

79.5
75.4
73.2

75
70

82.1

77.7

10% increase ofrain intensity≒3 times more
frequent storms

69.4
66.6

65

87.7

60.9

600(CCSR/NIES K-1 Simulation
Grid point near Tokyo)

100200300
400500
Heavy Rainfall
in X year return period"XX年に1度の豪雨"

600

http://hydro.iis.u-tokyo.ac.jp/
Changein Drought
Frequency

16

End of 21st century
compared with 20th century
Drought: daily riverdischarge is below
threshold of 10%
percentile

Decrease Drought

Increase Drought

Change in Flood
Frequency
End of 21st century
compared with 20th century
Frequency in the 21stcentury of 100-year
flood in the 20th century
Hirabayashi et al., (HSJ, 2008)
Based on CCSR-NIES AOGCM

Flood Increase

Flood Decreasehttp://hydro.iis.u-tokyo.ac.jp/

17

Impacts of climate change
on ecosystems related to water (3c)
 An intensification and expansion of wildfires is likely
globally, as temperatures increase and dry spells become
more frequent and more persistent. （IPCC AR4, WGII, TS, 2007）
 Greater rainfall variability is likely to compromise
inland and coastal wetland species through shifts in thetiming, duration and depth of water levels.
 Surface ocean pH is very likely to decrease further, by asmuch as 0.5 pH units by 2100, with atmospheric CO2
increases projected under the A1FI scenario. This isvery likely to impair shell or exoskeleton formation bymarine organisms requiring calcium carbonate (e.g.,corals, crabs, squids, marine snails, clams and oysters).

Counter Measures against CC
Mitigation (slow down the speed of CC)
Reduce the emission of green house gases
Also good for energy saving, air pollution,energy security (nuclear power), newindustry (solar panel, eco-car, …)

Adaptation (reduce disasters due to CC)Enhance the resilience of the society
Also solves the existing social issues: poverty,
vulnerabilities for natural disasters,sustainable energy, health, food andagriculture, ecosystem, transportation, …

http://hydro.iis.u-tokyo.ac.jp/

19Note that, with respect to ecosystems,
generic rather than specific adaptation
responses are required. Generic planning
strategies would enhance the capacity toadapt naturally. Examples of suchstrategies are: enhanced wildlife corridors,
including wide altitudinal gradients inprotected areas.

http://hydro.iis.u-tokyo.ac.jp/

20

Gaps and Needs
 Regional and high resolution
information on the future climate.
 Assessments on the impacts ofmitigation and adaptation
measures on environment andhuman society before decision
making.
 More communications amongsociety, scientists, and engineers.

Working Group II calendar•
•••
•
•••
•

LAM1:
ZOD
Informal Peer Review:
LAM2:
FOD
Expert Review:
LAM3:
SOD
Government & Expert Review:
LAM4: Literature cutoff (in press) FGD
Final Government Distribution:
Plenary:

January 2011
July ‐ September 2011
December 2011
June ‐ August 2012
October 2012
March ‐ May 2013
July 2013
October ‐ December 2013
March 2014

AR5/WGII Chapter 3 “Freshwater Resources”
Taikan Oki (taikan@iis.u-tokyo.ac.jp), CLAhttp://hydro.iis.u-tokyo.ac.jp/23Remarks
 Detection and attribution of long-term trends ,changes, and impacts should be carried out.
Temperature rise and sea level rise
Water quality deterioration, sea water intrusion, …

More frequent floods and droughts
Soil erosion, sediment loadOcean acidification
Publications with peer-review should be ready until
July (March for WGI) 2013 for AR5.

 Social changes should be considered in impact
assessments.

Science and Technologyto Save the Aqua Planet
ThankYou!!

 Monitor Changes
 Project Changes
 Assess Impacts
 Examine Possible
Adaptation Options
 Support Decision
Making, and Actions