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Abstract Detail

Ecological Section

Nicholson, Nancy [1].

Past and Future: Assessing the Impact of Agriculture on Climate Change in the Last 10,000 years.

Data sets from polar ice caps record temperature behavior of Earth for approximately the last half million years. My statistical investigation of recent interglacial periods indicates a substantially different climate in the most recent warm period compared to the previous four interglacials. Among differences are the range of temperature variations as well as the behavior of interglacial temperature means. Research in the 21st century has identified a density-sensitive ocean circulation "switching mechanism" for ice ages through the Atlantic ocean between polar ice caps. New information on deep salt circulation in the Arctic, North Atlantic and Indian Oceans is integrated with older literature.
Continental configurations of the last 33 million years created circumstances for growth of ice at the poles, or what has been termed “icehouse world.” Statistical comparisons point to creation of “greenhouse conditions” much earlier than industrial emissions occur, at about 10,000 years B. P.
This timing difference plus reluctance of Earth return promptly to icy conditions invites explanation with a proposed mechanism: influence of agriculture on density differences in the world ocean via changing land use practices that affected atmospheric gas composition and albedo in a critical region of the Northern Hemisphere.
I propose that human influences on climate have acted longer than usually supposed and have left their isotope signature on the atmosphere and deep ocean. Human influences have coincided with natural swings in climate, producing a record seen in Holocene sea ice and in cores from both ice caps. A proposed mechanism for this influence is human-based effects on density differences in world ocean circulation (the “Ocean Conveyor” of Broecker and Denton). This is a crucial aspect of understanding because humans inhabit the interface between atmosphere and ocean, where the atmosphere is heated from the bottom up and the oceans from the top down.

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Related Links:
Research concerning climate change (Greenland Ice core interpretation)
Ice Core gateway (Vostok, Antarctica) - NOAA

1 - Miami University, Arts and Sciences, Western College Program, Miami University, Oxford, OH, 45056, United States

agricultural ecology interglacial
holocene ocean temperatures and agriculture.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PEC023
Abstract ID:463


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