WG2 SPM. General Regional Impacts To California specifics. IPCC Scenarios

Transcription

1 WG2 SPM General Regional Impacts To California specifics IPCC Scenarios 1

2 Technological Change at 2100 A1FI Global A1B A1T Governance B1 Economic Development Environmental Country A A2 B2 Country B Country C Local Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20 Gross Domestic Product Growth at 2100 Global A1 Governance B1 Economic Development Environmental A2 B2 Local Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20 2

3 Energy Use at 2100 Global A1 Governance B1 Economic Development Environmental A2 B2 Local Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20 Technological Change at 2100 A1FI Global A1B A1T Governance B1 Economic Development Environmental Country A A2 B2 Country B Country C Local Adapted from Arnell et al. (2004). Global Environmental Change, 14:3-20 3

4 Figure TS.2. Summary characteristics of the four SRES storylines Equilibrium Climate Sensitivity Surface warming following a sustained doubling of CO2 concentrations Best estimate 3 C; likely C; very unlikely less than 1.5 C; higher values not ruled out 4

5 Projections of Future Changes in Climate Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century. Best estimate and assessed likelihood range for future temperature projections for first time Broadly similar to the TAR but not directly comparable Projections of Future Changes in Climate For the next two decades a warming of about 0.2 C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1 C per decade would be expected. Earlier IPCC projections of 0.15 to 0.3 o Cper decade can now be compared with observed values of 0.2 o C 5

6 Projections of Future Changes in Climate Best estimate for low scenario (B1) is 1.8 C (likely range is 1.1 C to 2.9 C), and for high scenario (A1FI) is 4.0 C (likely range is 2.4 C to 6.4 C). Broadly consistent with span quoted for SRES in TAR, but not directly comparable Projections of Future Changes in Climate Near term projections insensitive to choice of scenario Longer term projections depend on scenario and climate model sensitivities 6

7 Projections of Future Changes in Climate Projected warming in 21st century expected to be greatest over land and at most high northern latitudes and least over the Southern Ocean and parts of the North Atlantic Ocean Projections of Future Changes in Climate Precipitation increases very likely in high latitudes Decreases likely in most subtropical land regions 7

8 Projections of Future Changes in Climate There is now higher confidence in projected patterns of warming and other regional-scale features, including changes in wind patterns, precipitation, and some aspects of extremes and of ice. PROJECTIONS OF FUTURE CHANGES IN CLIMATE Snow cover is projected to contract Widespread increases in thaw depth most permafrost regions Sea ice is projected to shrink in both the Arctic and Antarctic In some projections, Arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century 8

9 PROJECTIONS OF FUTURE CHANGES IN CLIMATE Very likely that hot extremes, heat waves, and heavy precipitation events will continue to become more frequent Likely that future tropical cyclones will become more intense, with larger peak wind speeds and more heavy precipitation less confidence in decrease of total number Extra-tropical storm tracks projected to move poleward with consequent changes in wind, precipitation, and temperature patterns PROJECTIONS OF FUTURE CHANGES IN CLIMATE Based on current model simulations, it is very likely that the meridional overturning circulation (MOC) of the Atlantic Ocean will slow down during the 21st century. longer term changes not assessed with confidence Temperatures in the Atlantic region are projected to increase despite such changes due to the much larger warming associated with projected increases of greenhouse gases. 9

10 PROJECTIONS OF FUTURE CHANGES IN CLIMATE Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized. Temperatures in excess of 1.9 to 4.6 C warmer than pre-industrial sustained for millennia eventual melt of the Greenland ice sheet. Would raise sea level by 7 m. Comparable to 125,000 years ago. IPCC, 2007 North America "Warming in western mountains is projected to cause decreased snowpack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources IPCC, FAR 2007 North America section 10

11 Will California receive adequate precipitation? Little consensus wetter or drier Cayan et al Decreasing Snowpack Increasing Warming CA Climate Change Center Summary Report (2006) 11

12 Disturbances from pests, diseases, and fire are projected to have increasing impacts on forests, with an extended period of high fire risk and large increases in area burned. IPCC, FAR 2007 North America section WATER Many rivers that derive water at their source from melting glaciers or snow will have earlier peak runoff in Spring and an overall increase in run-off, at least in the short term.** The temporary increase in water flows will not always be welcome. For example, glacier melt in the Himalayas will increase flooding and rock avalanche risks, while flash flood risks will increase in inland areas in Europe.*** 12

13 Climate change impacts on forests Increased Temperatures (effects Productivity) CO 2 fertilization (effects Productivity) Longer Dry Season Increased vulnerability to: Widlfires Pests Direct mortality Shifts in species distribution Slide modified from Climate Impacts group, Washington Wildfires Frequency increased four fold in last 30 years. Western US area burned Source: Westerling et Al

14 Increasing Wildfire Frequency Increasing Warming CA Climate Change Center Summary Report (2006) Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution... IPCC, FAR 2007 North America section 14

15 Mean Sea Level Relative to 1990 (inches) Coastal structure must account for rising seas Year SF Bay sea level risen ~ 7 Inches over last century Cities that currently experience heat waves are expected to be further challenged by an increased number, intensity and duration of heat waves during the course of the century, with potential for adverse health impacts.. IPCC, FAR 2007 North America section 15

16 California Heat waves Summer 2006 in California --~ 160 deaths - greater than 25,000 cattle dead - impact on agricultural crops - impacts on energy supply and demand Projections 5 Higher Warming Range ( F) Medium Warming Range (5.5-8 F) Lower Warming Range (3-5.5 F) 4-6 times as many heat-related mortality 3-4 times as many heat wave days times as many heat-related mortality 2-4 times as many heat wave days 2-3 times as many heat-related mortality times as many heat wave days 4 Sources: Midwest suffers as heat bears down Carla Johnson, Associated Press, appearing in Houston Chronicle, July 31, 2006 (July 21 total + 163). California's Cattle Death Toll Surpases 25,000 USAgNet, July 31, California Climate Change Center 2006 California Climate Change Scenarios Report Produced by California Climate Change Center in collaboration with UCS Or Eighteen papers have been released involving researchers from: Scripps Institution of Oceanography, UC Berkeley, UC Davis, Santa Clara University, LBNL, LLNL, US Forest Service, Oregon State University, Union of Concerned Scientists State Agencies: ARB, DWR, and CEC. 16

17 Slide from California Air Resources Board presentation January 22, 2007 AB 32 California Global Warming Solutions Act (2006) Economy-wide GHG emission reduction to 1990 levels by 2020 (about a 30%) California Air Resources Board lead agency. California EPA and Climate Action Team will oversee multi-agency coordination. Legislature may also play role through budget process or through legislation to require certain regulations 17

18 AB 32 Implementation Slide from California Air Resources Board presentation January 22, 2007 Figure TS.6. Projected risks due to critical climate change impacts on ecosystems 18

19 Figure TS.8. Relative vulnerability of coastal deltas Figure TS.9. Direction and magnitude of change of selected health impacts of climate change 19

20 Links for US regional impacts: Northeast: Great Lakes: California: Gulf coast: Iowa: Alaska: 20