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Climate Change Our Present State of Understanding

Climate Change Our Present State of Understanding. Humboldt State University 06 April MMX. Jelte Harnmeijer NASA Astrobiology Institute & Department of Earth and Space Sciences University of Washington. }. (former affiliation). What’s in a name?. ‘Greenhouse effect’.

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Climate Change Our Present State of Understanding

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  1. Climate Change Our Present State of Understanding Humboldt State University 06 April MMX Jelte Harnmeijer NASA Astrobiology Institute & Department of Earth and Space Sciences University of Washington } (former affiliation)

  2. What’s in a name? ‘Greenhouse effect’

  3. What’s in a name? ‘Greenhouse effect’ ‘Global warming’

  4. What’s in a name? ‘Greenhouse effect’ ‘Global warming’ ‘Climate change’

  5. What’s in a name? ‘Greenhouse effect’ ‘Global warming’ ‘Climate change’ ‘Global climate destabilization’ climate, n. The characteristic weather conditions of a country or region; the prevalent pattern of weather in a region throughout the year, in respect of variation of temperature, humidity, precipitation, wind, etc., esp. as these affect human, animal, or plant life.

  6. What’s in a name? The People Science Policy

  7. What’s in a name? The People Science Policy

  8. What’s in a name? The People Science Corporations Media Policy

  9. Climate change is real ... IPCC (2007)

  10. Climate change is real ... IPCC (2007)

  11. ... and humans are to blame Gruber & Galloway (2009)

  12. IPCC (2007)

  13. ... and humans are to blame

  14. The Atmosphere Subsystem • Temperatures are increasing • Heat waves are increasing • Heavy precipitation events are increasing • Snow cover is diminishing • Weather is becoming less ‘climate-like’: • Less predictability • Greater amplitude variations with higher frequency Secular changes do not pose the primary threat

  15. How will greenhouse gas emissions trend? (1) Hydrocarbon demand, supply & availability ITPOES (2010)

  16. How will greenhouse gas emissions trend? (1) Hydrocarbon demand, supply & availability

  17. How will greenhouse gas emissions trend? (2) Population

  18. How will greenhouse gas emissions trend? (2) Population • ~9 billion people predicted by 2050 • China’s population has stabilized • ~ +750 million in India • Most newcomers in sub-Saharan Africa

  19. How will greenhouse gas emissions trend? (3) Industrialization / ‘Development’

  20. How will greenhouse gas emissions trend? (3) Industrialization / ‘Development’ • Developing countries currently provide almost half of the world’s primary commodity exports, whilst importing less than a third. • Industrializing today’s ~5 billion un-industrialized people and the net 3 billion newcomers would entail ~sextupling primary commodity output

  21. Geological context Zachos (2009)

  22. Geological context • Anthropocene CO2 concentrations *not* unprecedented • Anthropocene temperatures *not* unprecedented • But pace of change is paramount • Great future unknowns: • N2O • CH4 • ocean structure & circulation • cloud behaviour

  23. Geological context Positive feedback mechanisms accelerate change • Examples: • Ice-albedo feedback • Carbonate dissolution-ocean acidification

  24. Geological context Negative feedback mechanisms limit change • Examples: • Calc-silicate feedback cycle

  25. The Ocean Subsystem • In contrast to our atmosphere, our oceans equilibrate slowly • Timescale of 103 - 104 years typical • Over the coming centuries, physicochemical response of our oceans will strongly control climate • Marine biogeochemical cycling regulates key greenhouse gases

  26. The Ocean Subsystem Our oceans have absorbed ~1/3 of anthropogenic CO2 ... CO2 flux [moles m-2 year-1]

  27. The Ocean Subsystem Our oceans have absorbed ~1/3 of anthropogenic CO2 ... ... but there is a price to pay: pH ≈ - log10 [H+]

  28. The Ocean Subsystem Our oceans have absorbed ~1/3 of anthropogenic CO2 ... ... but there is a price to pay: pH ≈ - log10 [H+] Some CO2 dissolves: CO2 (g) = H2CO3 (aq) Which produces acidity: H2CO3(aq) = H+ (aq) + HCO3- (aq) Which dissolves carbonate:CaCO3 + 2H+ (aq) = Ca2+ (aq) + H2O + CO2 Which produces more CO2 ...

  29. The Ocean Subsystem • Implicated carbonate biosynthesizers: • Coccolithophores • Cnideria • (coral reefs, ...) • Foraminifera • Echinoderms • (starfish, sea urchins, ...) • Crustaceans • (crab, lobster, shrimp, crayfish, krill, barnacles, ...) • Molluscs • (bivalves, ...)

  30. The Ocean Subsystem Stramma et al. (2008)

  31. The Ocean Subsystem Stramma et al. (2008)

  32. The Ocean Subsystem • Temperatures are increasing • pH is decreasing • Oxygen Minimum Zones are expanding • Intense tropical cyclone activity is increasing • Sea level is rising

  33. Thinking ahead Prevent? or Adapt?

  34. Thinking ahead hope, n. – Gr.: ελπίς (elpis)

  35. Thinking ahead “anticipation of misfortune” hope, n. – Gr.: ελπίς (elpis)

  36. Thinking ahead IPCC (2007)

  37. Thinking ahead IPCC (2007)

  38. Thinking ahead “... the worst case scenario is that Earth would become like its sister planet, Venus.” Hawking (2007)

  39. Thinking ahead

  40. Thinking ahead

  41. Thinking ahead Lovelock (2005)

  42. Thinking ahead Prevent? or Adapt? (Coping not an option)

  43. Thinking ahead Post-hydrocarbon decay will be slow Solomon (2009)

  44. http://www.realfuture.org • This presentation • Further resources • Feedback & discussion

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