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Positions of the continents

Started by aristaeus63, 09/23/2008 01:04PM
Posted 09/23/2008 01:04PM | Edited 09/23/2008 01:05PM Opening Post
One large, but not often discussed, factor the drives the climate is the positions of the continents. It is thought that the Pliestocene ice age began when volcanic activity in present day Panama closed the isthmus of Panama. This caused a change in the ocean currents cutting off a heat source for the higher latitudes.

The Antarctic would not be so cold if Antartica was not there as the oceans are much better heat sinks than land. Land surrounding the Arctic keeps it colder than if it were more open.

The ulitmate global cooling theory is Snowball Earth. It theorizes that the Earth was covered with ice from pole to pole. Recent research indicates that it was more likely Slushball Earth. Either way though it would not be possible with out the continents position equatorially.

I have read and I saw this on a history channel show that because of the present day continental positions that the current warming would only delay the onset of the next ice age by 200 years.

Any thoughts?

Andreas

DSOs observed:
NGCs 2005, ICs 103, Other 70, Palomar GCs 6, Abell PNs 12, Herschel 400: 316.
Equipment
Celestron CPC 1100, Lunt 60mm Ha Solar Scope
Posted 09/23/2008 08:39PM #1
Andreas Saldivar said:

One large, but not often discussed, factor the drives the climate is the positions of the continents. It is thought that the Pliestocene ice age began when volcanic activity in present day Panama closed the isthmus of Panama. This caused a change in the ocean currents cutting off a heat source for the higher latitudes.

The Antarctic would not be so cold if Antartica was not there as the oceans are much better heat sinks than land. Land surrounding the Arctic keeps it colder than if it were more open.

The ulitmate global cooling theory is Snowball Earth. It theorizes that the Earth was covered with ice from pole to pole. Recent research indicates that it was more likely Slushball Earth. Either way though it would not be possible with out the continents position equatorially.

I have read and I saw this on a history channel show that because of the present day continental positions that the current warming would only delay the onset of the next ice age by 200 years.

Any thoughts?

Andreas

The position of the continents and tectonic processes do have a profound impact on climate, but operate on such lengthy timescales that they have little relevance to the 20th century warming trend and to predictions of climatic conditions over the next 200 years. Climatic deterioration during the Holocene can be attributed to several tectonic processes. The closing of the Isthmus of Panama, opening of the Magellan Strait, etc. Another critical factor was the Himalayan orogeny and the uplift of the Tibetan Plateau. Few problems in geology are as difficult to solve as paleoaltimetry, but the phases of uplift of the Tibetan Plateau certainly impacted Cenozoic climate. Click here to the publications page of Maureen Raymo: http://www.moraymo.us/climate_publications.php She has contributed a lot on the topic. If you don't have time to read them all, be sure to read through this one: http://www.moraymo.us/1992_Raymo_Nature.pdf


Over shorter timescales, like glacial-interglacial transitions ~100ka, orbital processes dominate the climatic signal. In particular the Milankovitch cycles. Without a rehash of theory, I simply point out that glaciations over the last 800ka years tend to last about 100ka separated by interglaciations of ~10ka. The current period we now live in, the Holocene, is an interglacial period that has lasted ~10ka. This has led some to predict the onset of full glacial conditions in the near geological future. But, hold on. When orbital dynamics are worked out for the future, it turns out that the insolation balance would not be suitable for another glaciation for millennia: http://www.sciencemag.org/cgi/content/summary/297/5585/1287 and the peak of the next glaciation should occur around 80000 years from now. All of this, of course, does not take into account anthropogenic CO2 emissions. University of Virgina prof William Ruddiman argues that the next glaciation would have already begun had it not been for human activities: http://www.personal.kent.edu/~jortiz/paleoceanography/ruddiman+al_qsr_05.pdf

Anyway, I guess my point is that, no, I don't think the current continental configuration will delay the next glaciation by 200 years.