Background about IPCC and Summary of Working Group 1 Report

1. Center of Ocean-Land-Atmosphere studies CLIM 101: Weather, Climate and Global Society Background about IPCC and Summary of Working Group 1 Report http://www.ipcc.ch/ipccreports/ar4-wg1.htm JagadishShukla Lecture14: Oct 16, 2008

2. Center of Ocean-Land-Atmosphere studies Global Warming: The known, the unknown, and the unknowable

3. Center of Ocean-Land-Atmosphere studies Intergovernmental Panel on Climate Change (IPCC) IPCC has been established by WMO and UNEP to assess scientific, technical and socio- economic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation. Working Group I: The Physical Science Basis Working Group II:Impacts, Adaptation and Vulnerability Working Group III:Mitigation of Climate Change • Largest number of U.S. scientists: nominated by the U.S. Govt. • Highest skepticism : “U.S. Govt.”

4. Center of Ocean-Land-Atmosphere studies • Geographic resolution characteristic of the generations of climatemodels used in the IPCC Assessment Reports: FAR (IPCC, 1990), SAR (IPCC, 1996),TAR (IPCC, 2001a), and AR4 (2007). • The figures above show how successive generationsof these global models increasingly resolved northern Europe. These illustrationsare representative of the most detailedhorizontal resolution used for short-termclimate simulations. • The century-long simulations cited in IPCC Assessment Reportsafter the FAR were typically run with the previous generation’s resolution. Verticalresolution in both atmosphere and ocean models is not shown, but it has increasedcomparably with the horizontal resolution, beginning typically with a single-layer slabocean and ten atmospheric layers in the FAR and progressing to about thirty levels inboth atmosphere and ocean.

5. The IPCC Assessments of ClimateChange and Uncertainties Center of Ocean-Land-Atmosphere studies

6. The IPCC Assessments of ClimateChange and Uncertainties Center of Ocean-Land-Atmosphere studies

7. Center of Ocean-Land-Atmosphere studies (Net) Global Warming • Warming • 1. Greenhouse gases (CO2, CH4, N2O) • CO2: Carbon Dioxide : Emission from fossil fuel • CH4: Methane : Agriculture • N2O: Nitrous Oxide • 2. Land use change • Cooling • Aerosols • Man made/Natural • Volcanoes ※Rate of increase of GHG is largest in 10,000 years

8. Center of Ocean-Land-Atmosphere studies CO2 emissions (Gigatons of Carbon, Gt C), IPCC 2007 1990: 6.4 Gt C (=23.5 Gt CO2 ), 2000-2005: 7.2 Gt C (=26.4 Gt CO2)

9. Center of Ocean-Land-Atmosphere studies Net CO2 Flux Takahashi et al. 2002

10. Center of Ocean-Land-Atmosphere studies Changes in Greenhouse Gases From Ice Age to Modern Data

11. Center of Ocean-Land-Atmosphere studies Monthly Mean Carbon Dioxide NOAA CMDL Carbon Cycle Greenhouse Gases Atmospheric carbon dioxide mixing ratios determined from the continuous monitoring programs at the 4 NOAA CMDL baseline observations. Principal investigator: Dr. Pieter Tans. NOAA CMDL Carbon Cycle Greenhouse Gases. Boulder, Colorado. (303) 497-6678

12. Center of Ocean-Land-Atmosphere studies Solar Irrandiance Recent analyses of satellite measurements do not indicate a long-term trend in solar irradiance (the amount of energy received by the sun), Frohlich and Lean (2005)

13. Center of Ocean-Land-Atmosphere studies The Knowns (Observed) • CO2 emissions have grown by 80% between 1970 and 2004. • (2005: 379 ppm; All GHG: 455 ppm (CO2 equivalent); • Primary reason: fossil fuel use and land-use change) • Rate of increase of CO2, CH4, N2O was the largest in 10,000 years. • Aerosols have partly offset the warming by CO2. • Global mean surface temp. increase (linear trend) 0.76oC in 100 years (1906-2005). • Eleven of the past twelve years are the warmest on record. • In the past 500 years, the warmest 50 years were 1951-2000.

14. Center of Ocean-Land-Atmosphere studies The Knowns (Observed) • Sea level has risen 1.8 mm/yr since 1961; 3.1 mm/yr since 1993. • Arctic sea ice extent reduced by 2.7% per decade since 1978. • (The summer minimum on record; 2007) • Enhanced run-off and earlier spring peak discharge in many glaciers and snow-fed rivers. • Extreme hot nights have increased ; frost days have decreased. • Earlier timing of spring events (blooms) on land. • Poleward and upward shifts in plant and animal ranges. • Changes in algal, plankton, and fish abundances (~Temp.). • Increase in the acidity of oceans.

15. Center of Ocean-Land-Atmosphere studies LAST TWO MILLENIA OR SO … 2000 Year Northern Hemisphere Reconstruction of Surface Air Temperatures Temperature Anomaly (oC)

16. Center of Ocean-Land-Atmosphere studies LAST CENTURY OR SO …

17. What’s Happening in the Ocean?

18. Center of Ocean-Land-Atmosphere studies Sea Level Rise over the Last Century Climate Change, 1995

19. Center of Ocean-Land-Atmosphere studies Greenland Ice Mass Greenland Grace monthly mass solutions. For the entire Greenland ice sheet, for April 2002 to April 2006, after scaling the results and removing the mean. The blue error bars include only the contributions from uncertainties in the GRACE gravity fields. Velicogna and Wahr (2006) Thanks: R. Cicerone

20. Center of Ocean-Land-Atmosphere studies FAQ 3.1, Figure 1

21. Linear Tropospheric Temperature Trends (°C per decade) for 1979 to 2005 Center of Ocean-Land-Atmosphere studies Figure 3.19

22. Center of Ocean-Land-Atmosphere studies Anomaly time series The US Historical Climatology Network (USHCN) data Figure 3.3 Relative to the 1961 to 1990 mean full US Historical Climatology Network (USHCN) data the USHCN data without the 16% of the stations with populations of over 30,000 within 6 km in the year 2000

23. Center of Ocean-Land-Atmosphere studies Annual Anomalies of Global Temperature Figure 3.2 Relative to the 1961 to 1990 mean

24. Center of Ocean-Land-Atmosphere studies Annual Global Land Precipitation Anomalies Figure 3.12 Relative to the 1981 to 2000 mean

25. Center of Ocean-Land-Atmosphere studies Global Mean Sea Level Relative to the 1980 to 1999 mean

26. Center of Ocean-Land-Atmosphere studies NH Average Snow-Covered Area (SCA) Figure 4.2

27. Center of Ocean-Land-Atmosphere studies Monthly Areal Extent of Seasonally Frozen Ground

28. Shrinking Sea Ice Extent in Arctic:Result of Global Warming? • High latitudes more vulnerable • Ice-albedo feedback • Perennial sea ice shrinking 9.6% per decade since 1979 2005 1979 Annual Minimum Sea Ice Extent (DMSP SSM/I)

30. Center of Ocean-Land-Atmosphere studies Observed and Projected Global Mean Warming

31. Center of Ocean-Land-Atmosphere studies Observed trends, Assessment of human influence on trends, and Projections of extreme weather and climate events

32. Center of Ocean-Land-Atmosphere studies Observed Rate of Sea Level Rise and Estimated Contributions from Different Sources

33. Center of Ocean-Land-Atmosphere studies Global Carbon Budget

35. Center of Ocean-Land-Atmosphere studies Mean of 15 Models Surface Air Temperature Difference (Sresa1b YR 71-100) minus (20c3m 1969-98), Global Average = 2.61

36. Center of Ocean-Land-Atmosphere studies AOGCM Projection of Surface Temperatures

37. Center of Ocean-Land-Atmosphere studies Projection of Precipitation

38. Center of Ocean-Land-Atmosphere studies Global and Continental Temperature Change Figure SPM.4

39. Center of Ocean-Land-Atmosphere studies The Knowns (Models) • Limits of deterministic prediction • (attribution of an event (Katrina) is not possible) • No model can explain the past 50 year observed global warming without increase in the green house gases (GHG). • Sun and volcanoes would have produced cooling. • There is no mechanism known to scientists that can explain the global structure of warming in the A, O, L without GHG. • Warming and sea level rise would continue for centuries, even if GHG were stabilized. • Increase in the frequency of heat waves and heavy precipitation. • Entire disappearance of arctic late summer sea ice ( ~ 2100 ).

40. Center of Ocean-Land-Atmosphere studies The Unknowns • Predictability of climate models for small regions and extreme events. • Change in the frequency and intensity of tropical cyclones. • Timing for complete elimination of the Greenland ice sheet. • (sea level will rise by 7 meters) • Antarctic ice sheet : too cold?, gain mass due to more snowfall? • The probability of large abrupt climate change. • Level of warming for extinction of species • ( 1.5 – 2.5oC: 20 - 30% ; > 4oC: > 40% ) • Carbon uptake by the oceans.

42. Center of Ocean-Land-Atmosphere studies STERN REVIEW: The Economics of Climate Change • Ignoring climate change will damage economic growth. The damages accelerate as the world gets warmer. • (The poorest countries and people will suffer earliest and most) • 2. The damage will be on a scale similar to those associated with the great wars and the economic depression of the first half of the twentieth century. • 3. It will be difficult or impossible to reverse changes. • 4. The earlier effective action is taken, the less costly it will be. • 5. Expected annual cost of emissions reductions for stabilization at 550 ppm CO2-eq. is likely to be around 1% of GDP by 2050. The cost of mitigation is modest relative to no action (risk ~ 5% loss of GDP per year).

43. Center of Ocean-Land-Atmosphere studies Adaptation, Mitigation, and Sustainable Development 1. Adaptation can reduce vulnerability to climate change. 2. Adaptive capacity is uneven across society and is connected to social and economic development 3. Substantial adaptation and mitigation can be achieved with existing technology. 4. Carbon pricing, either through taxes or cap-and-trade systems, is an essential incentive for implementing mitigation options. 5. There is a large low-cost mitigation potential between now and 2030 (energy infrastructure investment ~ 20 trillion dollars).

44. Center of Ocean-Land-Atmosphere studies The Unknowables • Breakthrough in Science and Technology • Alternative Source of Energy • Carbon Capture and Storage Technology • 2. Response of Social System to Global Change • Behavior of Humans (Life Style and Consumption) • Behavior of Govts. (War; Immigration; etc.) • 3. Abrupt and Catastrophic Climate Change • Sustainability of Population (Health, Agriculture) • Breakdown of Social Order • 4. What will be the Weather on 1 January 2100 ?

45. Center of Ocean-Land-Atmosphere studies What should “we” do ? • Immediate action on conservation and energy efficiency • Educate the public and help elect enlightened leaders and policymakers • International dialogues and negotiations • Social, economic, scientific, technological research to suggest options for adaptation and mitigation • Develop next generation models ( climate, social, economic ) for improved projections of climate change and consequences

46. Center of Ocean-Land-Atmosphere studies Immediate action with multiple benefits • Energy efficiency would: • decrease our dependency on foreign oil • improve our nation security • decrease our trade deficit • increase out national competitiveness • encourage development of new products for global marks • decrease household energy costs while also slowing the increases of CO2 and CH4 ! Thanks: R. Cicerone

47. Electricity Consumption/person in the US and California (current electricity generation in the US ~ 1 TW, 2020 ~ 1.4 TW) Thanks: R. Cicerone

48. Center of Ocean-Land-Atmosphere studies What should “we” do ? • Immediate action on conservation and energy efficiency • Educate the public and help elect enlightened leaders and policymakers • International dialogues and negotiations • Social, economic, scientific, technological research to suggest options for adaptation and mitigation • Develop next generation models ( climate, social, economic ) for improved projections of climate change and consequences

49. Center of Ocean-Land-Atmosphere studies THANK YOU! ANY QUESTIONS?