Tuesday, November 15, 2005

Cretaceous evidence of Climate Change

I'm working on a project at the moment that involves understanding the environment of what is present day West Africa before the South Atlantic formed due to plate tectonics (continental drift). The area between southern Africa and Brazil was a large rift valley, similar to those cutting through present day East Africa and the Red Sea. Large lakes existed between the soon to be separated continents. Sediments in those lakes were extremely rich in algal material and they have formed superb source rocks for hydrocarbons. So it is natural for us to study these ancient sediments when and where we can.

All manner of scientific analyses have been undertaken by academia and industry over the years. One of the most pertinent to the climate change debate is the realization that subtle changes in lake chemistry, algal growth and so on are probably related to sunspot activity. Changes in mineral content of the lake deposits seem to be on a cycle that spans several years, resulting in thin (millimeter thin) layers of alternately rich and lean source material.

When the data is plotted out, it is very apparent that the Cretaceous environment in these lakes was in a continuous state of flux. There was no "norm", in fact it is hard to define exactly what would be typical. With no man-made influences (all this was occurring approximately 120 million years ago) it is hard to blame anything but Nature for these fluctuations. External influences would most likely be from sunspot activity, creating climate variations, and slowly evolving geological processes such as erosion. These same influences are here today and they provide most of the effects the "greens" like to believe are caused by mankind.

That is not to say that mankind is incapable of creating climate change but how much and for how long are not known with any degree of precision. In other words, the warming period we appear to be enjoying is probably due to the same set of influences that created all those fluctuations in the proto-South Atlantic.


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