Arctic's sub-tropical past

[earthseed]

nexium:<br /><br />Transfer of heat from the tropics to the poles by air currents is an interesting idea. It seems to be the only method left to explain the temperature distribution of the Creteceous period. But, at least today, the Coriolis effect tends to deflect winds to an west-east direction. Maybe there was some force back then that caused a more south to north wind flow. Venus is barely rotating at all, so one would expect it to be quite different.<br /><br />Ocean currents want to do the same thing, but the peculiar shape of the North Atlantic forces the Gulf Stream to flow north. This transfers a lot of heat and moisture; the effect is more than local. Some believe it drives the climate for the entire Earth.<br /><br /><br />stevehw33:<br /><br />You have mentioned solar effect on climate a lot, sorry if I implied that you thought it was the only factor affecting climate. The paper I chose is an overview of current thinking on the subject, it is not just one person's theory. In my opinion, paleoclimitology is dealing in hard facts, and the quality of work is good. On the other hand, I share your opinion on papers that leap to conclusions based on climate models, which are definitely a work in progress at this point.

 

[earthseed]

I am not quite that negative about climate models. This is a valuable activity with many years of research behind it. But the key word is "research", or "work in progress". We should pay attention to the results, but not take them literally as a forecast of what will actually happen.<br /><br />These models are not equivalent to an engineering model describing a bridge. It is not possible to represent every physical process on the entire planet over many years, with the extremely limited resources we have. This kind of model must be developed on an iterative basis. Weather forecasting is like this, and it has gotten better with many years of improving the models based on feedback from the actual results. Unfortunately, it is difficult to get results from climate models, because the events in question have not happened yet. The best that can be done is model what has already happened, and this has been done with limited success.<br /><br />So when a climate model predicts that a doubling of carbon dioxide levels will, with water vapor feedbacks, cause a rise in average temperature of a few degrees, this should not be dismissed out of hand. These are real forces being described. But there may be other negative feedback forces that were missed.<br /><br />We do not know what doubling carbon dioxide levels will do. It might cause disruptive warming, as predicted in the models. It might trigger an ice age by reversing the Gulf Stream. It might lead to more climate instability. And there is a small chance it is preventing an ice age that would have happened without it.<br /><br />It seems very unwise to mess with something that could be so critical, and is so poorly understood.