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the Mid-Atlantic Ridge (Original)


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Author Topic: the Mid-Atlantic Ridge (Original)  (Read 11844 times)
Carolyn Silver
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« Reply #30 on: July 28, 2008, 10:14:44 pm »

Looking Farther into the Past

Most scientists believe that glacial-interglacial cycles are the result of relatively gradual, periodic changes in the Earth's orbital parameters that influence the seasonal distribution of solar radiation striking the surface of the earth. However, the record clearly shows that the transition between states was anything but gradual. The rapid climate response to the gradual changes in solar radiation is one of the most dramatic examples of abrupt climate change.

Because of its length, multiple data sets, and precision in dating, the Vostok ice core from Antarctica is one of our best records of glacial-interglacial cycling. One of the interesting perspectives from Vostok is the nearly simultaneous changes in temperature, carbon dioxide, and methane through time. The Vostok record also shows the sawtooth character of the glacial-interglacial cycle. Temperature and carbon dioxide decreased in a series of progressively cooler steps towards glacial maximum conditions. Each glacial state ended abruptly with a rapid transition to the full interglacial state marked by the warmest temperatures and highest levels of carbon dioxide in the atmosphere. Why the Antarctic region was cold during periods when southern hemisphere solar radiation was high is the subject of current investigation. The evidence suggests that the southern hemisphere cooling was driven by the reduced solar energy in the northern hemisphere. As the northern hemisphere cooled, carbon dioxide in the atmosphere dropped. The drop in concentrations of this radiatively important greenhouse gas then caused cooling in the southern hemisphere.


Figure 20. Because of its length, multiple data sets, and precision in dating, the Vostok ice core from Antarctica is one of our best records of glacial-interglacial cycling. One of the interesting perspectives from Vostok is the nearly simultaneous changes in temperature, carbon dioxide, and methane through time.

Data Links
For more on the GISP2 and GRIP ice core projects and their data, see NOAA Paleoclimatology's Greenland ice core projects page.
The Alley (2000) Greenland snow accumulation and temperature reconstructon can be found on that page as well.
Hulu cave data can be found at Wang et al. 2001
Data from the Cariaco basin off Venezuela include:
Haug et al. 2001 Cariaco Basin Trace Metal Data

Hughen et al 1996 Tropical Atlantic Deglacial Climate Change Data

Hughen et al. 2000 Synchronous Radiocarbon and Climate Shifts During the Last Deglaciation

Lea et al. 2003 Cariaco Basin Foraminiferal Mg/Ca and SST Reconstruction

Peterson et al 2000 Cariaco Basin Reflectance, Bulk Elemental Data

Data from the Vostok ice core can be found at NOAA Paleoclimatology's Vostok Data page.
The North Atlantic record of Heinrich events can be found at Bond et al 1992 Heinrich Event Data, DSDP 609.
The Arabian Sea record of Heinrich events can be found at Schulz et al. 1998 Arabian Sea Stable Isotope and TOC Data

http://www.ncdc.noaa.gov/paleo/abrupt/data_glacial3.html
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