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Abrupt Climate Change in the Glacial-Interglacial Record

Abrupt Climate Change in the Glacial-Interglacial Record. AOS 528, 11/27/07. Definitions of Abrupt. Large changes within less than a 30 year period Abrupt on human time scales (climatology), but… A transition or response that is rapid compared to the forcing. Relevant for any time scale

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Abrupt Climate Change in the Glacial-Interglacial Record

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  1. Abrupt Climate Changein the Glacial-Interglacial Record AOS 528, 11/27/07

  2. Definitions of Abrupt • Large changes within less than a 30 year period • Abrupt on human time scales (climatology), but… • A transition or response that is rapid compared to the forcing. • Relevant for any time scale • Incorporates the idea of thresholds, but… What is the definition of “large changes”? What’s the forcing and what’s a feedback?

  3. Definitions of Abrupt N2O CO2 What is rapid? CH4

  4. Sea Level Rise 1880 - 2100 Holocene and Projected Sea Level Rise 8,000 BP to 2100 Future rate similar to deglacial sea level rise. ~1m per century

  5. Glacial-Interglacial Abrupt Events • Abrupt events during glacials were larger and more widespread than during the most recent interglacial (Holocene) • Both cooling and warming events are identified (but none are warmer than modern climate) • Wide varieties of proxy data record these abrupt events

  6. Proxy Data and Abrupt Climate Events Meridional Overturning Circulation MOC CH4 Greenland Temperature Temperature Temperature nss-Ca2+ = non-sea salt Calcium Antarctica Dust / Iron CO2

  7. Proxy Data Findings • Abrupt warming and cooling events are recorded in both Greenland and Antarctica • Large methane signal (∆CH4=150ppb) • possibly related to changes in tropical wetlands or Asian monsoon • low CH4 correlated with increased dust in Antarctica (cold, dry and windy?) • Small carbon dioxide signal (∆CO2=20ppm) • Pollen records show equatorward shift of boreal tree lines (cold weather forests) during cooling events • Effects are global, but out-of-phase in N. and S. Hemispheres (i.e. Northern and Southern Hemisphere signals are not synchronous)

  8. Methane vs Carbon Dioxide • Large methane signal (∆CH4=150ppb) • possibly related to changes in tropical wetlands or Asian monsoon • low CH4 correlated with increased dust in Antarctica (cold, dry and windy?) • Small carbon dioxide signal (∆CO2=20ppm)

  9. Abrupt Climate Change and Atlantic Ocean Circulation Abrupt Cooling: Heinrich Events • Decreased NADW • NADW formation south of modern location Abrupt Warming: Dansgaard-Oeschger Events • Increased NADW • NADW formation north of modern location Heinrich Modern Atlantic Ocean Circulation Dansgaard/Oeschger

  10. Presentation Instructions • Submit presentations to me via email attachment by at least 11PM the night before your presentation. • Powerpoint presentations • 10 minutes + 5 minutes for questions 4 to 8 slides, including a title slide and a final slide summarizing conclusions • Each person in the group must present some of the material • Use plenty of images, and make sure fonts are large enough to read in the back of the room • Speak so people can hear you in the back also • Talk slowly and precisely, and PRACTICE! • Remember that there will be two dates for the Final Powerpoint Presentations: December 6th (during class) and December 20th (during the final exam from 10:05-12:05) • Everyone is expected to show up for all group presentations! I will have a sign-in sheet available those days.

  11. Powerpoint Presentations: December 6th Presentations: Thursday, December 6th (during class) Term papers: Thursday, December 13th (midnight) Group 2: Phillips, Schiferl The Effectiveness of the Kyoto Protocol Group 7: Schmidt, Bruskewitz, Serwe: Title? Group 8: Schuh, Moore, Olson Effects of Global Warming on Agriculture Production in the Midwest Group 9: Kirchner, Shewczyk, Welhouse Global Climate Change's Effects On Agriculture Group 10: Franklin, Obbink, Orland The Effects of Orbital Forcings During Mid-Pliocene Global Warming

  12. Powerpoint Presentations: December 20th Presentations: Thursday, December 20th (10:05am) Term papers: Saturday, December 8th (midnight) Group 1: Lubcaynka, Moua, Propheter US and China's Affect on Global Warming Group 3: Caruso, Maloney, Schmelzer Title? Group 4: Schreiber, Brown "Peak Oil" Predictions and Their Effect on Future Warming Group 5: Asuma, Caves, Koch A Comparison of Global Climate Effects Due to Varying Rates of Methane Introduction Group 6: Marsicek, Ronnei, McCarville Using Drought Index to Analyze Potential Impacts on the Tropical Rainforest By Increasing CO2 and Solar Luminosity Group 11: Hladish, Kampa A Potential Glacial Maximum in the Future?

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