On Feb 2, 10:28 pm, Robert Indigo Ellison <[email protected]> wrote:
- Not read the study just the usual posting -http://www.gizmag.com/ mini-ice-age-hit-in-months/13489/. - There was - about a 20 degree temp change in Greenland between the younger Dryas - and now. I didn't say globally - but very rapid change apparently - happened in Ireland. This would be quite dramatic I'm sure you would - agree. Yes, but your link refers to the entry into the Younger Dryas when temperatures dropped. If you look at the figure on your web page of the Younger Dryas you will see there was an even larger jump, to a higher temperatures at the end of the Younger Dryas. If we are warming the Earth with CO2 will the jump be to a cooler state or to a warmer state? It is claimed by everybody that we know why there was a sudden cooling - the draining of a pro-glacial lake stopped the THC. But what caused the sudden warming - did a pro-glacial lake fill from the Atlantic? Even if the cause was a resumption of the THC why was it so sudden? And if fresher water in the Arctic is going to cause an ice age, why didn't we flip into one during the Little Ice? It seems to me more likely that the draining of Lake Agassiz caused the GIN (Greenland, Iceland, and Norwegian) seas to freeze over. Fresh water has a higher freezing point than salty. It was the ice cover which caused the cooling, and the stopping of the THC. When that sea ice melted suddenly due to the ice albedo effect, the climate suddenly warmed and the THC resumed. The THC is a symptom not a cause. When the Arctic sea ice disappears it will do so suddenly, and temperatures will jump due to the change in albedo. That is a chaotic system with positive feedbacks (e.g. ice-albedo) and non-linear effects such the surface warming when ice melts. And it is predictable to an extent - when will the ice disappear? - I came across an aphorism form Neils Bohr - one of the original - quantum physicists. 'Prediction is very difficult, especially if it's - about the future.' Most people have been thinking about climate as - ordered forcing by greenhouse gases on one side or natural climate - cycles that come and go like the seasons on the other. Well that is where they go wrong. Climate is both forcing by greenhouse gases AND natural cycles. In fact the greenhouse effect is secondary to the solar cycle. - Climate is a cascade of - powerful systems - ice, cloud, dust, oceans, heat transport, - atmosphere, biology - that is characterised by abrupt, rapid and - sometimes extreme climate change. Classic behaviour of a dynamic and - complex system in chaos theory. - Climate is a chaotic system and it is free to jump around like a - spinning top on a rough surface - limited only by the strange - attractor phase space topography. No, chaos does not necessarily mean random. It is actually stable with bounds. - I have to admit I was much more - sanguine about climate change when I thought there were climate - cycles. Well I don't think you are unusual. The problem is to get others to accept that climate is not only driven by natural cycles. Cheers, Alastair. -- You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/globalchange
