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Climate feedbacks for global warming

Climate feedbacks for global warming. Review of last lecture. Global climate models: Earth system models (5 components) Global climate models can reproduce the observed warming in the 20th century. The warming is largely caused by human activities.

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Climate feedbacks for global warming

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  1. Climate feedbacks for global warming

  2. Review of last lecture • Global climate models: Earth system models (5 components) • Global climate models can reproduce the observed warming in the 20th century. The warming is largely caused by human activities. • Projected change: mean temperature (largest warming over Arctic, larger over land), mean precipitation, sea level, extreme temperature, extreme precipitation, fresh water, ecosystems • Future climate scenarios show that reducing greenhouse gas emissions can substantially mitigate warming in the latter half of this century.

  3. How do human activities change the global climate? Human beings are changing the global climate system in three different ways: • Change land cover (deforestation and afforestation) • Release or cleanse pollutants (aerosols) • Release or cleanse greenhouse gases

  4. Observed Change in Global Temperature: Significant warming

  5. Global map of temperature change: Largest warming in Arctic (“Arctic amplification”)Larger warming over land than ocean

  6. Projected Change in Global Temperature: Significant warming The spread comes from uncertainties in climate feedbacks

  7. Main climate feedbacks for global warming • Ice albedo • Temperature (Lapse rate) • Water vapor • Cloud • Aerosol • Carbon cycle

  8. Ice albedo feedback – Arctic amplification

  9. Video: Effect of Arctic Amplification • https://www.youtube.com/watch?v=GWj2DzKn7MA

  10. Temperature (lapse rate) feedback Larger Longwave flux Tropopause Warming of whole troposphere Same lapse rate Surface Surface warming Cooling down of surface temperature

  11. Water vapor feedback

  12. Cloud feedback Stronger warming effect Stronger cooling effect

  13. Aerosol feedback

  14. Video: Carbon Cycle • http://www.youtube.com/watch?feature=player_detailpage&v=U3SZKJVKRxQ

  15. Global carbon cycle

  16. Carbon cycle feedback Example 1: Permafrost thaw

  17. Carbon cycle feedback Example 2: Biosphere

  18. Carbon cycle feedback sources

  19. Summary • Large spread in projected temperature change comes from uncertainties in climate feedbacks • Main climate feedbacks for global warming: ice-albedo, temperature (lapse rate), water vapor, cloud, aerosol, carbon cycle

  20. Works cited • http://www.jpl.nasa.gov/images/earth/20100325/atlantic20100325-full.jpg • http://www.nasa.gov/centers/goddard/news/topstory/2004/0315humidity.html • http://sitemaker.umich.edu/section2_group1/arctic_issues__permafrost • http://www.all-creatures.org/hope/gw/02_Arctic-Antarctic.htm • http://www.fedre.org/en/content/global-permafrost-zones-high-resolution-images-google-earth • http://www.onlyzerocarbon.org/arctic_feedback.html • https://www.marietta.edu/~biol/biomes/tropdry.htm • http://www.nwf.org/Wildlife/Threats-to-Wildlife/Global-Warming/Global-Warming-is-Causing-Extreme-Weather/Wildfires.aspx • http://www.opb.org/news/blog/ecotrope/qa-how-to-reduce-wildfire-severity-even-in-a-warmer-climate/

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