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The importance of longevity in a greenhouse gas as climate forcing

The importance of longevity in a greenhouse gas as climate forcing. David Archer University of Chicago. Joseph Fourier. Joseph Fourier described the greenhouse effect in 1827. Memoires d l’Academie Royale des Sciences de l’Institute de France VIIII, 570-604 (1827).

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The importance of longevity in a greenhouse gas as climate forcing

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  1. The importance of longevity in a greenhouse gas as climate forcing David Archer University of Chicago

  2. Joseph Fourier Joseph Fourier described the greenhouse effect in 1827 Memoires d l’Academie Royale des Sciences de l’Institute de France VIIII, 570-604 (1827)

  3. Energy Balance of a Bare Rock Tearth = 259 K = -14° C = 6°F

  4. A Planet with an Atmosphere Tatm = 259 K Tearth = 303 K = 86° F

  5. John Tyndall, 1859 John Tyndall discovered that CO2, H2O, and CH4 are greenhouse gases. O2 and N2 are not.

  6. CO2 is a greenhouse gas Resting State Symmetric Stretch O C O C O O No Resting Dipole IR Inactive Asymmetric Stretch Bend C O O O C O -1 -1 2349 cm 660 cm

  7. Earth’s outgoing infrared spectrum

  8. The band saturation effect

  9. Radiative Forcing goes as ln(CO2)

  10. Svante Arrhenius Svante Arrhenius calculated that doubling CO2would warm the Earth by 4-6°C, in 1896

  11. The water vapor feedback + W a t e r V a p o r F e e d b a c k W a t e r V a p o r C o n c e n t r a t i o n + T e m p e r a t u r e

  12. The Runaway Greenhouse Effect

  13. The ice albedo feedback + I c e A l b e d o F e e d b a c I c e M e l t s + T e m p e r a t u r e

  14. David Keeling David Keeling started measuring CO2 concentration in the atmosphere

  15. The biosphere breathes

  16. Various public predictions of detectable human-caused warming by year 2000 Charney report and others

  17. Climate forcings Only greenhouse gasforcing looks like therecent temperature rise. Crowley, 2000

  18. What about phenomenaundreamed-of? The sun is good at pushing our climate buttons. Clouds? Humidity? “They blame CO2 because they can’t think of anything else.”

  19. A detective story The Butler. Found holding a smoking gun next to the deceased. Forensics matches the gun with the bullets. The Chauffer. In Kentucky for sister’s wedding. “Can’t think of any way he could have done it.” To convict the Chauffer, we’d have to first unconvict the Butler.

  20. Airborne fraction of fossil fuel CO2 Century timescale peak Airborne Fraction of Carbon Released Millennial timescale tail

  21. IPCC 2001 and earlier Summaries for Policymakers IPCC 2001 and earlier reports implied that global warming would last about a century.

  22. Everyone gets this wrong Rutledge 2011 Shindell, 2012 Ramanathan 2008

  23. Paleocene/Eocene Thermal Maximum Event 55 Myr Ago A natural releaseof CO2, comparableto the potential fossil fuel release. Warming, with a recovery that took100,000 years. Zachos et al. 2001

  24. Long Tail Model Intercomparison Project LTMIP • D. Archer, M.l Eby, V. Brovkin, A. Ridgwell, L. Cao, U. Mikolajewicz, K. Caldeira, K. Matsumoto, G. Munhoven, A. Montenegro, Ann. Rev. Earth Sciences, 2009.

  25. Band saturation effect of IR absorbtion by CO2 emphasizes the tail 1800 1600 1400 1200 pCO2 1000 800 600 400 200 0 6 5 °C 4 3 2 1 0 0 100 300 400 500 200 kyr

  26. Seawater pH Chemistry CO2 + CO3= + H2O <--> 2 HCO3- 10 100 2000 mM Concentration in seawater CO2 uptake capacity is determined by CO3=

  27. Atmosphere / Ocean Equilibrium 600 Gton C 1800 Gton C as CO3= We expect a partitioningof ~1:3 between air andocean Gton C = 1015 g

  28. Atmosphere / Ocean Equilibrium Airborne Fraction of CO2 Slug 4000-5000Gton 1000-2000Gton Archer 2005 22% 33% Lenton 2006 21-26% 34% CLIMBER 22% 35% Goodwin 2007 24-26% 40% Ridgwell 2007 31%

  29. Atmosphere / Ocean Equilibrium Affected by: changes in circulation biology ocean temperature saturating the carbonate ion buffer

  30. Flakiness in ocean / atmosphereequilibrium

  31. Neutralization by CaCO3 CO2 + CaCO3 + H2O ==> Ca2+ + 2 HCO3-

  32. How long does it take? Neutralization e-folding timescale Archer 2005 5-8kyr Lenton 2006 500 - 1000 yr Ridgwell 2007 1-2 kyr Tyrell 2007 2-3 kyr Pulls the airborne fraction down to ~ 10%

  33. The Silicate Weathering CO2 Thermostat Volcanic CO2 degassing CaSiO2 -> Ca2+ + SiO2 Weathering = function( CO2 ) Ca2+ + CO3= -> CaCO3 CaCO3 + SiO2 -> CaSiO2 + CO2 Burial + Subduction

  34. The Silicate Weathering CO2 Thermostat CO2 >100,000 years Helps explain Carl Sagan’s “Faint Young Sun” paradox

  35. Time scale must be longer than this

  36. Sea Level Sea Level, m 100 Eocene 40 Myr ago 50 Pliocene 3 Myr ago Global Mean T, °C Today IPCC 5 10 15 20 Forecast Year 2100 -50 -100 Last Glacial Maximum 20 kyr ago -150

  37. Methane

  38. Methane is about here CO2 is here

  39. Methane is about here CO2 is here

  40. Methane

  41. Methane

  42. Earth’s temperature response toradiative forcing RF Climate sensitivity: D T / D RF Upper 100m Time scale: 10 yrs Thermal bufferof the deepocean: Time scale 1000 yrs DeepOcean

  43. Shindell, et al 2012

  44. CO2 vs. CH4 CO2 poses a “trap” for humanity, because of the time separation of the cause and the impacts, which will continue to worsen essentially forever. It’s like an ever-intensifying curse on our descendents, or planting a cancer. The climate impacts from CH4 peak and subside within a human timescale. “Good” cholesterol vs. “Bad” cholesterol?

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