abrupt climate change in the glacial-interglacial record aos 528, 11/27/07
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Abrupt Climate Changein the Glacial-Interglacial Record
AOS 528, 11/27/07
Large changes within less than a 30 year period Abrupt on human time scales (climatology), but…
A transition or response that is rapid comparedto the forcing.
Relevant for any time scale Incorporates the idea of thresholds, but…
Definitions of Abrupt
What’s the forcing and what’s a feedback?What’s the forcing and what’s a feedback?
What is the definition of “large changes”?What is the definition of “large changes”?
CO2
CH4
N2O
Definitions of Abrupt
What is rapid?
Sea Level Rise1880 - 2100Sea Level Rise1880 - 2100
Holocene and Projected Sea Level Rise8,000 BP to 2100Holocene and Projected Sea Level Rise8,000 BP to 2100
Futurerate similar to deglacial sea level rise.~1m percentury
Futurerate similar to deglacial sea level rise.~1m percentury
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
Temperature
Dust / Iron
CO2
Antarctica
Proxy Data and Abrupt Climate Events
Temperature
CH4
MOC
Temperature
Meridional Overturning Circulation
Greenland
nss-Ca2+ = non-sea salt Calcium
Proxy Data Findings
1. Abrupt warming and cooling events are recorded in both Greenland and Antarctica
2. 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?)
3. Small carbon dioxide signal (∆CO2=20ppm)
4. Pollen records show equatorward shift of boreal tree lines (cold weather forests) during cooling events
5. Effects are global, but out-of-phase in N. and S. Hemispheres (i.e. Northern and Southern Hemisphere signals are not
synchronous)
Methane vs Carbon Dioxide
1. 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?)
2. Small carbon dioxide signal (∆CO2=20ppm)
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
Modern Atlantic Ocean Circulation
Heinrich
Dansgaard/Oeschger
Presentation Instructions1. Submit presentations to me via email attachment by at least 11PM the night
before your presentation.
2. Powerpoint presentations a) 10 minutes + 5 minutes for questions
4 to 8 slides, including a title slide and a final slide summarizing conclusions
b) Each person in the group must present some of the materialc) Use plenty of images, and make sure fonts are large enough to read in
the back of the roomd) Speak so people can hear you in the back alsoe) Talk slowly and precisely, and PRACTICE!
3. 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)
4. Everyone is expected to show up for all group presentations! I will have a sign-in sheet available those days.
Powerpoint Presentations: December 6th
Presentations: Thursday, December 6th (during class)Term papers: Thursday, December 13th (midnight)
Group 2: Phillips, SchiferlThe Effectiveness of the Kyoto Protocol
Group 7: Schmidt, Bruskewitz, Serwe:Title?
Group 8: Schuh, Moore, OlsonEffects of Global Warming on Agriculture Production in the Midwest
Group 9: Kirchner, Shewczyk, WelhouseGlobal Climate Change's Effects On Agriculture
Group 10: Franklin, Obbink, OrlandThe Effects of Orbital Forcings During Mid-Pliocene Global Warming
Powerpoint Presentations: December 20th
Presentations: Thursday, December 20th (10:05am)Term papers: Saturday, December 8th (midnight)
Group 1: Lubcaynka, Moua, PropheterUS and China's Affect on Global Warming
Group 3: Caruso, Maloney, SchmelzerTitle?
Group 4: Schreiber, Brown"Peak Oil" Predictions and Their Effect on Future Warming
Group 5: Asuma, Caves, KochA Comparison of Global Climate Effects Due to Varying Rates of Methane Introduction
Group 6: Marsicek, Ronnei, McCarvilleUsing Drought Index to Analyze Potential Impacts on the Tropical Rainforest By Increasing CO2 and Solar Luminosity
Group 11: Hladish, KampaA Potential Glacial Maximum in the Future?