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CCE seminar series Dr. John Perona, series coordinator This presentation available at:

Explore the intricate relationship between Earth's biogeochemistry and climate change. Learn about the carbon cycle, greenhouse warming, and models for limiting temperature rise. Discover the impact of human activities on atmospheric CO2 levels and the Earth's systems. Gain insights into the natural carbon cycle, fossil fuel emissions, and the role of greenhouse gases in global warming.

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CCE seminar series Dr. John Perona, series coordinator This presentation available at:

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  1. CCE seminar series Dr. John Perona, series coordinator This presentation available at: www.pdxClimateEd.com portlandccl.org/citizens-climate-education/

  2. James Lovelock Originator of the Gaia hypothesis Earth is self-regulating Life affects planetary evolution Biology integrated with chemistry and geology: Biogeochemistry Biogeochemistry + physics + ecology = Earth systems science www.youtube.com/watch?v=6eixcaTVd_c&feature=related

  3. CARBON CYCLE • GREENHOUSE WARMING • MODELS AND TEMPERATURE (limiting warming to <2°C)

  4. Keeling curve – atmospheric CO2 ~280 ppm = pre-industrial https://scripps.ucsd.edu/programs/keelingcurve/

  5. Composition of Earth’s Atmosphere O2 N2 CO2 [404 ppm]

  6. Keeling curve ~280 ppm = pre-industrial https://scripps.ucsd.edu/programs/keelingcurve/

  7. The rate of CO2 buildup is generally increasing

  8. World CO2 emissions have flattened out! ~32 billion metric tons CO2 emitted ~9 billion metric tons C (2016) Data from International Energy Agency (IEA)

  9. Keeling curve ~280 ppm = pre-industrial https://scripps.ucsd.edu/programs/keelingcurve/

  10. Northern hemisphere summer decrease The Earth breathes! Jan. Jan.

  11. Two questions from the data 1. Why does CO2 in the atmosphere always increase in the Northern winter and decrease in the Northern summer? 2. Why does the amount of extra CO2 that accumulates in the atmosphere vary so much from year to year?

  12. Carbon in Nature (gas forms) • Combined only with oxygen • Fully oxidized form • Lowest energy form • Doesn’t burn – already fully combined with oxygen • Combined only with hydrogen • Least oxidized form • Highest energy form • Burns in air (O2) to form CO2 • and water (H2O) Methane, CH4 (natural gas)

  13. Carbon in Nature (liquids, solids) • Glucose (C6H12O6) • Carbon combined with C, H and O [CH2O] • Intermediate energy • Burns in air but yields less energy than CH4 • “Fixed” carbon in life forms • Limestone crystal (calcite) • Carbon combined with oxygen and calcium • Mineral form • Long-term carbon storage

  14. FOSSIL FUELS Methane – “natural gas” – CH4 “C” to “H” ratio is low  less CO2 “cleanest” fossil fuel GAS OIL Octane – typical in petroleum Intermediate “C” to “H” ratio COAL • Typical hydrocarbon in coal • Highest “C” to “H” ratio • Produces most CO2 COAL – PRODUCES TWICE AS MUCH CO2 AS GAS

  15. Northern hemisphere summer decrease The Earth breathes Jan. Jan.

  16. Carbon Cycle on Earth’s Surface Light CO2 + H2O  O2 + CH2O Plants and some bacteria  [CO2]  in North summer O2 + CH2O  CO2 + H2O Animals and other bacteria RESPIRATION

  17. Two questions from the data 1. Why does CO2 in the atmosphere always increase in the Northern winter and decrease in the Northern summer? 2. Why does the amount of extra CO2 that accumulates in the atmosphere vary so much from year to year?

  18. Carbon Cycle Natural carbon cycle on Earth’s surface (left) Some carbon in plants/animals (biomass) gets buried to form fossil fuels, some O2 released Humans drill out and burn fossil fuel (right)

  19. “FAST” CARBON CYCLE + 9 billion tons C 800 billion metric tons (metric ton = 2200 lb) +3b +2b

  20. How CO2 is removed from air • photosynthesis and respiration cycle (fast) • dissolves in oceans (hundreds of years) • CaCO3 equilibrates in ocean (thousands yrs) • volcanoes/weathering (100s thousands yrs) • After 1000 years: • 15-30% of CO2 remains in the atmosphere • After 100,000 years: • 7% of CO2 remains in the atmosphere

  21. Long-term fate of atmospheric CO2 following a large release from fossil fuel burning “fast” carbon cycle (limestone) “slow” carbon cycle volcanoes today Climatic Change 90, 283-297 (2008)

  22. Human emissions Where human emissions go

  23. The rate of CO2 buildup is generally increasing

  24. CARBON CYCLE • GREENHOUSE WARMING • MODELS AND TEMPERATURE (limiting warming to <2°C)

  25. UV/visible Short l High energy Earthlight Infrared light Long l Low energy 30% reflected 50% absorbed

  26. Natural greenhouse effect ~ 33ºC of warming [-18ºC to +15ºC]

  27. Greenhouse gases? YESNO Water vapor (strongest) 50% O2 20% N2 ~5% methane

  28. Climate change drivers 404 ppm CO2 ~ 480 ppm CO2eq Albedo = 30%

  29. IPCC-AR5 Earth IR out: 240 W/m2

  30. Why is Alaska warming so fast? Ice Albedo Positive Feedback Loop Warming from GHG  some ice melt => WHITE ICE turns into DARK OCEAN  less sunlight reflected => more warming  more ice melt…

  31. UV/visible Short l High energy Infrared light Long l Low energy

  32. IPCC-AR5 Earth IR out: 240 W/m2

  33. Methane 1.8 ppm Pre-industrial ~0.7 ppm Where does methane come from? Why is it increasing in the atmosphere?

  34. Sources of methane Natural sources ~35% Human sources ~65%

  35. Methane sources and sinks Present growth rate ~ 10 million tons/year Lifetime (t1/2) ~ 9 years. Well-defined sink  CO2

  36. Permafrost and other Northern peatlands – Will warming cause catastrophic methane release? [for now unlikely] Old, deeply buried frozen soil carbon (CO2, CH4) only contributes a small amount of methane Surface layers do contribute significantly Helps future modeling Nature Climate Change, Jul2017

  37. IPCC-AR5 Earth IR out: 240 W/m2

  38. Comparing Hazards of Greenhouse Gases Concentration, Half-life, Global warming potential GHG Half-life Concentration CO2Not definable404 ppm Methane 9 years 1.8 ppm Nitrous oxide 114 years 0.3 ppm CFC-12 100 years 0.5 pp-billion (ppb) HFC 23 260 years 24 pp-trillion (ppt) HFC 134a 14 years 63 pp-trillion (ppt)

  39. Global Warming Potential (GWP) • How much IR radiation (Earthlight) a GHG can absorb, • compared to CO2 • Depends on the chemical structure of the • GHG and which Earthlight wavelengths it absorbs • GWP is defined for a specific timeframe • (commonly 20 years or 100 years)

  40. Comparing Hazards of Greenhouse Gases Concentration, Half-life, Global warming potential GHG GWP (100 yr) Half-life CO21 not definable Methane 45 9 years Nitrous oxide 265 114 years CFC-12 (banned) 10,200 100 years HFC 23 12,400 260 years HFC 134a 1,300 14 years

  41. Banning HFCs – An enormous opportunity to reduce global warming now • HFC’s replaced CFC’s as refrigerants, under Montreal Protocol (1989) to repair the ozone hole • But HFCs are very strong GHGs! • Kigali Amendment to Montreal Protocol (2016): phases out all HFCs • US Senate has not yet ratified Kigali • 2015 Obama EPA rule to phase out HFCs – rejected August 2017 by the DC Circuit Court • Federal and state legislation?

  42. Possibilities for Banning HFCs • If US Senate ratifies Kigali Amendment, with implementing legislation: 85% reduction in US HFCs by 2036 [Globally: estimated reduced warming by 0.5 ºC] • California SB1383 Reduces HFCs by 40% from 2013  2030 • Oregon – no HFC law Clean Energy Jobs Bill – includes HFCs as a greenhouse gas under cap & trade

  43. #1 solution to reverse global warming: “manage refrigerants” (Ban HFC’s)

  44. CARBON CYCLE • GREENHOUSE WARMING • MODELS AND TEMPERATURE (limiting warming to <2ºC)

  45. Temperatures compared to 20th C average Warming didn’t stop here! 2000s: Deep ocean warmed instead of surface

  46. Connecting GHG increases with temperature increases: Climate sensitivity High sensitivity Temp. increase Low sensitivity CO2 amount Doubled CO2 How much Temp. increase from 2x CO2? Must estimate from climate models

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