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Henning Rodhe Department of Meteorology Stockholm University rodhe@misu.su.se

Historical perspectives on climate change science Climate forcings by greenhouse gases and aerosols. Henning Rodhe Department of Meteorology Stockholm University rodhe@misu.su.se. Literature. 1. Callendar G.S. 1938. Artificial production of carbon dioxide

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Henning Rodhe Department of Meteorology Stockholm University rodhe@misu.su.se

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  1. Historical perspectives on climate change scienceClimate forcings by greenhouse gases and aerosols Henning Rodhe Department of Meteorology Stockholm University rodhe@misu.su.se

  2. Literature • 1. Callendar G.S. 1938. Artificial production of carbon dioxide • and its influence on temperature. Quarterly Journal of the • Royal Meteorological Society, 64, 223-240. • 2. Rodhe H, Charlson R. 1998. The legacy of Svante Arrhenius • Understanding the greenhouse effect. Ambio Vol 26 (1997) • p. 2-5: Svante Arrhenius and the Greenhouse effect • (H Rodhe, R Charlson, E Crawford) • Additional reading material: • p. 17-24: A review of the contemporary global carbon • cycle and as seen a century ago by Arrhenius and • Högbom (M Heimann)

  3. Brief history of our understanding of the GHE 1824 First qualitative description Fourier 1896 First quantitative estimate Arrhenius 1909 First use of the term GHE Wood 1938 First claim that the GHE is observed Callendar 1967 First estimate using a General circulation model (GCM) Manabe & Wetherald

  4. The famous 1896 paper by Svante Arrhenius

  5. The energy balance of planet Earth Heat radiation (IR) Solar radiation S = 1360 W/m2 R Balance: T4 = S(1-albedo)/4σ T = 250 K = -23o C Income: πR2 S (1-albedo) Loss: 4πR2σT4

  6. The Greenhouse effect H2O CO2 CH4 Clouds GHG and clouds re-radiate to the ground

  7. Without GHG the Earth would be covered by ice and snow “Snowball Earth”

  8. Absorption of radiation in the atmosphere Visible window IR window

  9. The effect of GHG on the effective altidue of IR radiation to space Rodhe et al. Ambio 1997

  10. Approximate contributions to the natural GHE H2O 60 % CO2 25 O3 8 CH4 6

  11. Approximate contributions to the anthropogenic GHE CO2 55 % CH4 16 O3 12 Halocarbons 11 N2O 5

  12. IPCC 2007

  13. IPCC 2007

  14. What determines the future climate? • The emissions of CO2 • (+other GHG and aerosol particles) • 2. The response of the carbon cycle • (the ”airborne fraction”) • 3. The response of the physical • climate system (climate sensitivity)

  15. Climate sensitivity ∆T = S x ∆F

  16. Contributions to climate sensitivity (Equilibrium temperature change at 2x CO2) CO2 alone 1.2K CO2 + H2O 2.2 CO2 + H2O + other feedbacks: Clouds, ice/snow, surface 2.0 - 4.5

  17. The carbon cycle

  18. Measurements of CO2 and O2 at Mauna Loa IPCC 2007

  19. Atmospheric CO2 during the past 1200 years Direct measurements From ice cores

  20. CO2,CH4 and estimated global temperature (Antarctic ice cores) 0 = 1880-1899 mean. Source: Hansen, Clim. Change, 68, 269, 2005. CH4 1765 ppmv 2007 CO2 380 ppmv 2007

  21. The global carbon cycle for the 1990’s IPCC 2007

  22. Time scales in the global carbon cycle Turn-over time of CO2: Atmosphere 3 yr Surface oceans 5 Deep oceans 4000 Soils & vegetation 20 Relaxation time for a pulse input to the atmosphere: >100 yr

  23. Annual accumulation of atmospheric CO2 If all emissions stayed in the atm. Observed rate of increase IPCC 2007

  24. Airborne fraction Accumulation in the atmosphere Emissions from fossil fuels ca 55 % Accumulation in the atmosphere Total man-made emissions ca 45 %

  25. Feedback processes in the carbon-cycle/climate system Terrestrial systems - Climatic regulation of C exchange - Effects of elevated CO2 conc. ”CO2 fertilization effect” - Fire - Other nutrients and pollution (N, O3) - Changes in land use practices - Forest regrowth

  26. Net C uptake by plants CO2 conc.

  27. 1700 – 1990: -0.1 1700 – 2100: -0.35 Ocean acidification

  28. Anthropogenic GHE not just CO2

  29. CO2 CH4 N2O IPCC 2001

  30. Recent changes in GHG conc. CO2 CH4 N2O CFC-11 CFC-12 CFC-113 HCFC-22 IPCC 2007

  31. The concept of CO2 equivalents The basic definition: the CO2 concentration that would give the same climate forcing as the forcings of all long-lived GHG added together Total GHG forcing = 5.35 log(CO2eq/CO2preind) The current conc. of CO2eq is about 450 ppmv Difficulty: The effects of particles, O3 .. If these are included CO2eq = 375 ppmv

  32. Read (glance through) Callendar’s paper and try to answer/discuss the following questions. I will ask you to report back to the rest of us. Some of the results can preferably be shown as a ppt figure.1. Measurements of the concentration of CO2 in the air were few and not so reliable when he wrote his paper (mid 1930's). How do his estimates of the conc. agree with current estimates for the same period? Evelyne2. How does his projection of the CO2 conc. in 2100 agree with current scenarios? Discuss the difference. Petter3. How large increase in global mean temperature did he estimate for a doubling of the CO2 conc.? How does that compare with estimates made Arrhenius in 1896 and those made today? Liselott4. Compare his estimate of the change in the observed global mean surface temperature between 1880 and 1930 with the current estimate. Paul5 What was his conclusion regarding the "urban heat island" effect and its influence on the global temperature record? Ylva6. He suggested that the observed increase in temperature was caused by the simultaneous increase in CO2 conc. How concerned was he about this? Wing7. What were the main objections to his paper by his colleagues? Marie-Luise 8. Callendar's estimate of the "airborne fraction" was considerably higher than what we now know. Why? John1/9 2011Henning Rodhe

  33. Man’s impact on climate Not just GHG

  34. Direct effect Indirect effect

  35. Pollution haze over NE India and the Bay of Bengal December 2004

  36. Få partiklar - rent Många partiklar - förorenat The impact aerosols on cloud reflectivity

  37. Negative forcing by aerosols (mainly sulfates) comparable to the positive forcing by CO2 IPCC 2007

  38. The impact by greenhouse gases has been masked by the aerosol cooling

  39. Some aerosol particles heat the planet ”black particles” - soot

  40. Annual mean optical depth due to BC All sources Without biofuel cooking Ramanathan & Carmichael 2008

  41. Global aerosol forcing (Direct + indirect, W/m2) Soot Sulfate etc. Total +0.9 -2.3 -1.4 Ramanathan & Carmichael 2008

  42. Positive forcings CO2 CH4 etc. Soot Trop. O3

  43. Policy

  44. Stabilization scenarios IPCC

  45. In order to stabilize the conc. of CO2 in the atm. the emissions have to be greatly reduced It is not enough to stabilize the emission

  46. CO2 stabilization scenarios Azar & Rodhe 1997

  47. CO2 emissions per capita and per country in the year 2000

  48. Ackumulerade utsläpp av CO2 1750 - 2006

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