Intergovernmental Panel on Climate Change (IPCC) 4th ... · Intergovernmental Panel on Climate Change (IPCC) 4th Assessment Report Summary for Policymakers June 21, 2007. 2 Overview
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1California Environmental Protection Agency
California Air Resources Board
Intergovernmental Panel on Climate Change (IPCC)
4th Assessment Report
Summary for Policymakers
June 21, 2007
2
OverviewFeb 2007 The Physical Science Basis
Apr 2007 Impacts, Adaptation and Vulnerability
May 2007 Mitigation of Climate Change
Nov 2007 Final Synthesis Report
New New
3
Policy-relevant but not policy-prescriptive reviews of the state of scientific understanding
1,250 authors2,500 reviewers130 countries6 years work
1 consensus report
IPCC 4th Assessment (2007)Climate Change 2007
The Physical Science Basis
4
Constraints on IPCC4th Assessment
• End of 2005 cut-off for research• Important findings in 2006 not included
– Rapid Greenland and Antarctic ice melt– Sea surface temperatures– Hurricane intensity– Sea level rise
• Computer climate models to be improved for short-term projections (1-2 decades)
• Policy makers need more frequent, comprehensive, but succinct summaries
5
Physical Science BasisKey Findings
“Warming of the climate system is unequivocal…”
“Most of the observed warming over the last 50 years is likely to have been due to
the increase in greenhouse gas concentrations.”
“Very high confidence that the globally averaged net effect of human activities
since 1750 has been one of warming…”
Source: IPCC Climate Change 2007: The Physical Science Basis—SPM
6
Changes in Heat-trapping Gases from Ice-Core and Modern Data
Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.
“Since the dawn of the industrial era, CO2 and other key heat-trapping gases have increased at a rate that is very likely to have been unprecedented in more than 10,000 years.”
7
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Was
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Source: IPCC Climate Change 2007: The Physical Science Basis—SPM
Global Average Temperature
Global Average Sea Level
Northern Hemisphere Snow Cover
1850 19501900 2000
Direct Observations of Recent Climate ChangeN
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8
1900 1950 2000
0.0
0.5
1.0
Year
Tem
pera
ture
ano
mal
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)Predicted and Observed Temperature Change
North America
Source: IPCC Climate Change 2007: The Physical Science Basis—SPM
Natural climate drivers only
Natural plus human climate driversObservations
9
Predicted and Observed Temperature Change
There has been significant human-induced warming over past 50 years in each continent
Source: IPCC Climate Change 2007: The Physical Science Basis—SPM
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Ashley CooperPicimpact/Corbis
NA
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UK
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“It is likely that since 1970, human-induced warming has had a discernible influence on
many physical and biological systems.”
89% of the 29,000 datasets that IPCC examined exhibited changes in the direction
expected from warming.
Impacts, Adaptation and VulnerabilityKey Findings
Source: IPCC 2007: Climate Change Impacts, Adaptation and Vulnerability—SPM
11
Effects of human-induced climate change are now apparent on every continent
National Park Service
NA
SA
Ashley CooperPicimpact/Corbis
Source: IPCC 2007: Climate Change Impacts, Adaptation and Vulnerability—SPM
US
GS
UK.gov NA
SA
Avalanche
Coral BleachingDrought
Flood
Thaw
Glacier Melt
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Heatwave
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Flood
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Future Risks:Rise Above 1980-1999 of 1-2°C (1.8-3.6°F)
Source: IPCC 2007: Climate Change Impacts, Adaptation and Vulnerability—SPM
Most corals bleached
NO
AA
Increase cereal productivity mid-high latitudes
Decrease cereal productivity low latitudes
Far
mtr
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Far
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.org Decrease
freshwater availability for billion peopleShehzad Noorani
UNICEF
Disappearance of Glaciers
Up to 30% of species at increasing risk of extinction
New York Times
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Replacement of tropical forest by savanna in eastern Amazon
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Future Risks: Rise Above 1980-1999 of 2-3°C (3.6-5.4°F)
Source: IPCC 2007: Climate Change Impacts, Adaptation and Vulnerability—SPM
Millions more people could experience coastal flooding each year
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~15% of terrestrial biosphere becomes net carbon source
Ashley CooperPicimpact/Corbis
Widespread coral mortality
NA
SA
US
GS
Large increase area burned
14
Future Risks: Rise Above 1980-1999 of 3-4°C (5.4-7.2°F)
Source: IPCC 2007: Climate Change Impacts, Adaptation and Vulnerability—SPM
~40% of terrestrial biosphere becomes net carbon source
Ashley CooperPicimpact/Corbis
Decrease cereal productivity some regions
Decrease all cereal productivity low latitudes
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~30% of global coastal wetlands lost
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High latitudes flood
Commit to long-term ice sheet melt contribution of 4-6 meters sea level rise
5 m
Increases in coastal water temperature worsens cholera abundance
15
Future Risks: Rise Above 1980-1999 of 4-5°C (7.2-9.0°F)
Source: IPCC 2007: Climate Change Impacts, Adaptation and Vulnerability—SPM
Baard Naes - BBC
Sea ice reduction in Canadian Arctic
UK.gov
Increased mortality from droughts
Altered distribution of disease vectors
Increased frequency of cardio-respiratory diseases due to climate-induced smog
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ldre
n’s
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pita
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akla
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Increased deaths, disease, and injury due to floods
AP
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Significant extinctions around the globe
16
“Although many early impacts of climate change can be effectively addressed through adaptation, the options for successful adaptation diminish and
the associated costs increase with increasing climate change.”
Source: IPCC 2007: Climate Change Impacts, Adaptation and Vulnerability—SPM
17
Mitigation of Climate ChangeKey Findings
“There is substantial economic potential for the mitigation of global greenhouse gas
emissions over the coming decades, that could offset the projected growth of global
emissions or reduce emissions below current levels.”
Source: IPCC Climate Change 2007: Mitigation of Climate Change—SPM
18
Global emissions will increase 25-90% by 2030 (compared to 2000 levels), unless we take immediate actions.
Source: IPCC Climate Change 2007: Mitigation of Climate Change—SPM
Methane
RefrigerantsNitrous Oxide
Carbon Dioxide0
20
40
60
80
100Gigatons of carbon dioxide-equivalent/year
2000 2030-Increasing Emission Scenarios
Global Emissions for 2000 and Projected Emissions for 2030
19
Cost of Mitigation to Limit Temperature Rise in 2030
2.0 – 2.8
2.8 – 3.2
3.2 – 4.0
Global mean temperature
increase (oC)
< 0.12< 3445 – 535
< 0.10.2 – 2.5535 – 590
< 0.06-0.6 – 1.2590 – 710
Reduction of average annual GDP growth
rates(%)
Range of GDP
reductionPresent-2030
(%)
Stabilization levels
(ppm CO2-eq)
Source: IPCC Climate Change 2007: Mitigation of Climate Change—SPM
20
• Emissions from some developing countries are growing rapidly, and curtailing them will need to be part of the solution.
• However, the U.S. and other developed countries bear a historical responsibility for most of the emissions in the atmosphere.
Roles of Developed and Developing Countries
Source: IPCC Climate Change 2007: Mitigation of Climate Change—SPM
21
Gov Schwarzenegger’s June 2005 Executive Ordercommissioned thisClimate Assessment, whichinvestigated potential climate change impacts and formed key scientific background for California’s GHG emissions legislation, Assembly Bill 32
California Climate Change Scenarios
Assessment
22
Key ConclusionsNumerous observations of long-term
changes in climate
Very high confidence that human activities have contributed to recent warming
effectsFurther warming unavoidable due to past
emissions, so climate adaptation investments are needed
Developing countries face a disproportionate burden of the damage
and costs of climate change
Substantial technologies and policy instruments available for greenhouse
gas mitigation
23
The degree of climate change our children and grandchildren experience in the second half of this century depends on the actions
we take in this and the coming decade.
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Union of Concerned Scientists
Thank you
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