1. Climate Change: A Scientist’s Perspective Taplin Lecture Princeton Environmental Institute April 7, 2011 Ralph J. Cicerone, President National Academy of Sciences

2. What is Happening? Is There an Explanation? Is There An Alternate Explanation? What Can Be Predicted? Science and Climate Change

3. Earth’s Energy Balance The Greenhouse Effect Observed Changes Temperatures of Air and Water Sea-Level Rise Ice Losses from Greenland & Antarctica Future Fossil-Fuel Usage OUTLINE

4. Over Earth’s history, climate has changed many times (global sea level, ice amounts, windiness, rain amounts). What forces control or influence climate? How can humans affect our planet’s climate?

9. 239 102 341 68 169 390 327 90 16 H 2 O, CO 2, O 3 Earth receives visible light from hot Sun and Earth radiates to space as a blackbody at infrared wavelengths

10. Calculating the Surface Temperatures of Planets for Venus Actual T e = 450 ºC Greenhouse effect and clouds, high pressure S(1 -  e  for Earth, S = 341 W/m 2,  = 0.3, so we calculate T e = - 18 ºC (or - 32 ºF) Greenhouse effect & clouds are needed WRONG ! for Mars T e = - 28 º C (± 5 º C) (large day/night swings) Greenhouse effect is very small, low pressure OK ! Infrared Visible

11. [Hanel et al. (1972)]

12. Energy in the Climate System Averaged over the whole Earth All Human Energy Usage 0.025 watts/meter 2 Extra Heat Trapped by Greenhouse gases (2007) 2.6 watts/meter 2 Energy Absorbed from Sunlight 239 watts/meter 2

13. www.scrippsco2.ucsd.edu

14. http://agage.eas.gatech.edu

15. [Hansen and Sato (2004)]

16. CO 2 Increase is from Human Activities: Approximate Fractions 85% from fossil fuels 15% from deforestation

18. http://data.giss.nasa.gov/gistemp/graphs 12 Jan 2011

19. http://data.giss.nasa.gov/gistemp/graphs 12 Jan 2011

20. http://data.giss.nasa.gov/gistemp/graphs/

21. Levitus et. al. (2009) Time series of yearly ocean heat content (10 22 J) for the 0–700 m layer from this study (solid) and from Levitus et al. [2005a] (dashed). Each yearly estimate is plotted at the midpoint of the year. Reference period is 1957–1990.

22. 1882-2005 sea level rise based on Permanent Service for Mean Sea Level (PSMSL) tide gauge data from 23 sites selected by Douglas (1997) This figure was prepared by Robert A. Rohde http://www.globalwarmingart.com/wiki/Image:Recent_Sea_Level_Rise.png Relative Sea Level (cm)

23. Source : University of Colorado, Boulder http://sealevel.colorado.edu

24. Greenland Mass Loss – From Gravity Satellite

25. Velicogna (2009 GRL), updated by Velicogna (2011)  Trend Apr 2002-Sep 2010:  -240±33 Gt/yr (= 0.7 mm/yr sea level rise)  ACCELERATION: -17 ±8 Gt/yr 2 Greenland Ice mass loss from GRACE

26. Antarctica Ice mass loss from GRACE  Trend Apr 2002-Sep 2010:  -143 Gt/yr (= 0.4 mm/yr sea level rise)  ACCELERATION: -17 Gt/yr 2 Velicogna (2009 GRL), updated by Velicogna (2011)

27. Global annual mean surface temperature anomalies, observed and calculated. From Stott et. al. (2006) ALL NATURAL

28. Physical Principles Explain the Warming Since the late 1970’s through the Greenhouse Effect

29. http://data.giss.nasa.gov/gistemp/graphs 12 Jan 2011

30. Solar irradiance through September 2008. Reference: Fröhlich, C. and J. Lean, Astron. Astrophys. Rev., 12, pp. 273--320, 2004. http://www.pmodwrc.ch/pmod.php?topic=tsi/composite/SolarConstant

31. Boden & Marland (2009) cdiac.ornl.gov Global Fossil-Fuel Carbon Dioxide Emissions, 1751 to 2007 Includes Cement Manufacturing All emissions estimates are expressed in million metric tons of carbon

32. EIA, International Energy Statistics database (as of November 2009), web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010). World marketed energy consumption, 1990-2035 (quadrillion Btu)

33. EIA, International Energy Statistics database (as of November 2009), web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010). Shares of world energy consumption in the United States, China, and India, 1990-2035 (percent of world total)

34. EIA, International Energy Statistics database (as of November 2009), web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010). Coal consumption in selected world regions, 1990-2035 (quadrillion Btu)

35. Pre-Industrial 280ppm 380ppm 425 ～ 440ppm Present Dangerous Level Global Carbon Cycle Management Anthropogenic Emission 7.2 GtC / y Absorption 3.1 GtC/ y How to control the tap to avoid risk industrialization CO2 in Atmosphere Ocean 2.2 Land 0.9 2ppm/y ex: 2.4-2.8 ℃ rise from PI Feedback Adapted from Nishioka, NIES, Japan

36. In future climate: Global temperatures ? Sea-level rise ? Precipitation amounts in each region and season? Frequencies of extreme events? How to limit CO 2 emissions from fossil-fuel burning?

37. Oceans acidifying as well as warming pH history and “business as usual” projection Red line is global annual average; blue lines show ocean-to-ocean and seasonal variation. Surface ocean pH has already fallen by 0.1 pH unit. Projected additional changes are likely to have large impacts on corals and other ocean organisms that make skeletons/ shells from calcium carbonate.

38. Article 2, UN Framework Convention on Climate Change (1992) “The Ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable in a sustainable manner.”

39. Who Should Define "Dangerous" ? scientists? elected leaders? ____________ ?

42. Clathrate Decomposition 5? Tg/yr (0.9%) Termites 40 Tg/yr (7.4%) Freshwaters 5 Tg/yr (0.9%) Wetlands 115 Tg/yr (21.3%) Boreal: 20 – 60 Tg/yr Oceans 10 Tg/yr (1.9%) Rice Paddies 110 Tg/yr (18.5%) Biomass Burning 55 Tg/yr (10.2%) Landfills 40 Tg/yr (7.4%) Global Methane Release Rates Coal Mining 35 Tg/yr (6.5%) Gas Production 45 Tg/yr (8.3%) Enteric Fermentation 80 Tg/yr (14.8%) Cicerone & Oremland, 1988Total = 540 Tg/yr

43. Immediate action with multiple benefits. Energy efficiency would:  decrease our dependency on foreign oil  improve our national security  decrease our trade deficit  decrease local air pollution  increase our national competitiveness  encourage development of new products for global markets  decrease household energy costs while also slowing the increases of CO 2 and CH 4 !

45. Evidence Time history of CO 2 increase and that of fossil-fuel usage Amounts of atmospheric CO 2 increase (0.6 x fossil-fuel emissions) Contemporary atmospheric amounts exceed those of previous four glacial cycles Geographical patterns of atmospheric CO 2 Isotopic contents of CO 2 Ice-core data show that CH 4 and N 2 O amounts are also unprecedented

46. Extreme heat waves in Europe, already 2X more frequent because of global warming, will be “normal” in mid-range scenario by 2050 Black lines are observed temps, smoothed & unsmoothed; red, blue, & green lines are Hadley Centre simulations w natural & anthropogenic forcing; yellow is natural only. Asterisk and inset show 2003 heat wave that killed 35,000. Stott et al., Nature 432: 610-613 (2004)

47. EIA, International Energy Statistics database (as of November 2009), web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010). World electricity generation by fuel, 2007-2035 (trillion kilowatthours)

48. EIA, International Energy Statistics database (as of November 2009), web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010). Renewable electricity generation in China by energy source, 2007-2035 (billion kilowatthours)

49. EIA, International Energy Statistics database (as of November 2009), web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010). World liquids consumption by region and country group, 2007 and 2035 (million barrels per day)

50. EIA, International Energy Statistics database (as of November 2009), web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010). World liquids consumption by sector, 2007-2035 (million barrels per day)

51. The challenge of scale Stabilizing at 500 ppmv CO 2 -e means global CO 2 emissions must be ~7 GtC/yr below BAU in 2050. Avoiding 1 GtC/yr requires… -energy use in buildings cut 20-25% below BAU in 2050, or -fuel economy of 2 billion cars ~60 mpg instead of 30, or -carbon capture & storage for 800 1-GWe coal-burning power plants, or -700 1-GWe nuclear plants replacing coal plants, or -1 million 2-MWe(peak) wind turbines replacing coal power plants or -2,000 1-GWe(peak) photovoltaic power plants replacing coal power plants Socolow & Pacala, 2004