Climate Change over thousands of years

19 Feb 2012

This post is informative ... see 'Sudden Climate transitions during the Quaternary' ... and is about a whole series of rapid climate transitions over the time span of the last few million years. The most detailed information concerns the YD to Holocene temperature change at 9500BC - which happened very quickly. However, the speed of this change is representative of similar but less well documented climate transitions prior to that date. These include the very cold Heinrich events, and various warmings (known as inter-stadials) and the beginning and ending of Inter Glacial episodes (the last of them being the Eemian at 125,000 years ago). Various mechanisms such as changes in ocean circulation, changes in atmospheric concentrations of greenhouse gases, or even haze particles creating opaque skies, or change in snow and ice cover etc have variously been invoked to explain these sudden regional and global transitions. What does it all mean?

Mike Stopa is a physicist with a blog and in this post, see he asks, what if the CAGW people are wrong? What will happen when the truth is out? He doesn't appear to believe too much in the feedback mechanism that is supposed to increase the effects of co2 in the atmosphere, creating runaway warming. This view is somewhat similar to that of physicist Peter Warlow when he spoke at one of our SIS speaker meetings. Now, the post itself is interesting - but nothing much out of the ordinary. What caught my eye was one of the comments, and there are lots of them at the end of the article. A warmist was clearly perplexed by the idea that co2 might not cause warming. He said, this would imply the whole Ice Age theory was awry as it was heavily supported by the co2 levels warming/ cooling idea. In effect, this is most damning - the Milankovitch cycles by themselves are not powerful enough to create the Ice Ages, he seemed to be saying. Is this true?

I've been reading, on and off for a month or so, a book by David Beeling, 'The Emerald Planet: How Plants Changed Earth's History' (Oxford University Press:2007) and it seems to be saying that if co2 does not cause global warming it is going to affect a lot more of science than just climatology. Now, I was under the impression that continental drift accounted for fossil forests in the Arctic and warm water molluscs in the Antarctic during the Dinosaur Age. Even in the early Cenozoic the Arctic was warm and conifers were growing on Ellesmere Island which is not so long ago in the grand scheme of geological time. However, the theory of Plate Tectonics has been upgraded. Back in the 1980s the 'Sunday Times Book of the Countryside' could claim the British Isles slowly drifted around the globe. When the coal fields were formed, back in the Carboniferous Period, it was tropical and straddled the equator and since then it has been slowly moving northwards, the land rising and falling, tilted, bent and buckled as it lurched from one geological era to the next. It now seems that the consensus is that the former positions of the world's landmasses have been pinned down by the orientation of Earth's magnetic field locked into rocks and no, opinion is that in the Dinosaur Age the continents were very close to where they are now.

Now, this creates a very real problem. Why was it tropical in the Arctic if the continents had not moved around - but Poles do not move do they? In order to account for the situation as it could not be denied it had been very warm at the Poles, and the fact that places that are now land were submerged (such as southern England and northern France) which must of course be due to higher sea levels rather than redistribution of global water, it was decided the Dinosaur Age coincided with a period of intense global warming. I have heard a geologist in a public talk actually say this, and Naomi Oreskes, notorious as an alarmist and warmist supporter, also wrote a highly rated book on Plate Tectonics and therefore we can see why she is so strongly in favour of CAGW. If greenhouse gases did not cause runaway warming there would be no explanation for the tropical climate at the North Pole in the Dinosaur Age - and her books and articles on Plate Tectonics would be barking up the wrong tree. Now, how many other scientific theories are dependent on co2 creating a warming planet. How deep is the malange - a recent theory that has claimed the attention of too many people it seems, as it was convenient rather than common-sense. 

There were no coal fired power stations back then - but there was lots of volcanic activity. Did volcanoes spew co2 into the atmosphere and create a runaway warming - but wait, volcanoes are often said to spew lots of undesirable particles into the atmosphere that cause coolings. According to the book (above) the climate was tropical in the Arctic during the Jurassic and Cretaceous not because of continental drift or Pole shift but because of global warming - and I thought I had bought a book about the origins and evolution of plants and trees. Fossils of breadfruit trees have been found in sediments off the western coast of Greenland (it seems to have been at the time above sea level but this discrepancy is not mentioned as problematic but apparently the sea-bed here appears to have been connected to the mainland), and these grow nowadays in places such as New Guinea, Malaya and Micronesia. Fossils of fish eating crocodiles that swam in fresh water lakes and rivers were also found - in sediments on the bottom of the sea, and various other indicators of tropical temperatures. Meanwhile, on a geological field survey not very long ago I was informed, on finding fossils of oysters and various shellfish, even the odd shark's teeth, that in the Jurassic the particular part of central England had an environment likened to the Florida Keys today. Why was it cooler in NW Europe than it was in the Arctic? Something seems to be amiss here and co2 appears to be a problem, in part as the main culprit at large appears to be the fossil magnetism found in rocks - or the interpretation thereof.