I gave a speech last week at my tennis/squash club on climate change (which presents speeches from time to time). I included some geological concepts that I don’t usually have an opportunity to talk about. The class of scientist who tend to be most unimpressed with IPCC-type climate science are geologists – which is where I got started in this. If you took an Oreskes-type survey among geologists, I don’t believe for a minute that you would get anything like IPCC solidarity. Unlike most scientists, geologists also happen to know a lot about climate history. Here’s an interesting graphic that I used: This is taken from http://www.scotese.com, which has many interesting portrayals of past climate history from a geological point of view. I’m going to post up some more snippets from my presentation in the next week whenI’m not otherwise distracted. There are (at least) 3 things that I find interesting about this graph: 1) from a geological point of view, we are still in an Ice Age. The most recent Ice Age (not individually discernable on this graph), the one ending from 12-17,000 years ago, was one of the deepest in the entire history of the earth; 2) past climate changes have been much larger than the experience of the last millennium; 3) perhaps more surprising, earth’s temperature has careened out of control either up into a Venus-like hothouse of down into a Mars-like icehouse. I don’t get the impression that a whole lot is definitively known about either the causes of major climate change or the reasons for stability. Update (afternoon): Here’s another graphic from http://www.scotese.com showing climate in the Eocene (Early Tertiary ~ 50 MM years). The caption read as follows:
During the Early Eocene alligators swam in swamps near the North Pole, and palm trees grew in southern Alaska. Much of central Eurasia was warm and humid.
One point that is easily lost sight of is the tremendous progress made in plate tectonics so that the location of these Eocene fossils from a polar region can be relied on i.e. one can’t just say that these were tropical fossils which have been transported into polar latitudes by continental drift. So one would certainly not be able to say that 1998 was the warmest year in the past 50 million years. – not even close.