Computer to the Rescue

9 Sep 2013

At ... computer simulation solves another puzzle. The beginning of the last glacial period required an accumulation of snow at higher latitudes to form the ice sheet that expanded from the poles to cover a vast area of the northern hemisphere. Snow fall is associated with high humidity and moderate temperatures - it is when the rain meets cold air that it turns to snow (as we regularly can see on weather forecasts as produced for television). Snow does not form in the freezing weather, enough to feed a growing glaciation. Now a combination of sea sediments, dating back to the start of a very cold period of the last Ice Age, starting around 80,000 years ago, has shown that the Bay of Biscay water temperature remained warm - in spite of the alleged cold weather. Now, there are various reasons that could be brought to the table but we have a consensus theory and so the explanation reflected the strongly held belief that Ice Ages were a reality. Actually, the explanation is rather good, and not to be sniffed at. Computer simulation was used to rescue the mainstream theory - and strengthen it. The paper is at Nature Geoscience and while it is true that no alternative scenario is explored to account for the warm waters detected in the Bay of Biscay (when according to the theory it should have been cool) the rescue by the computer negates that aspect. What appears to be shown in the study is that the Gulf Stream was blocked on its journey northwards and warm sea water from the Caribbean circulated around the Bay of Biscay with nowhere else to go. Modelling of warm water currents was involved in the study - but it is not clear if they took into account that a large chunk of the continental shelf system around NW Europe was above sea level during the Ice Ages. The assumption is that the European continent was cold and the ocean was warm, hence rain became snow when the cold air met the warm air system, with winds driving the snow northwards to create the conditions for an ice sheet to form. Therefore, what was originally a problem turned out to be a boon for the Ice Age theorists - providing a nice mechanism for snow accumulation.