Attended a really interesting talk last week, the ANU’s Jager Hales lecture which this year was given by Professor Edouard Bard (Collège de France & CEREGE Univ. Aix-Marseille, France) about the end of the last ice age, where from about 18,000 to 10,000 years ago the Earth slowly thawed out. It wasn’t a process that occurred smoothly across the globe, and in fact it was delayed significantly, even reversed, in the north Atlantic area and Europe due to the amount of ice melt from the Laurentide ice sheet (which was the 4km thick slab of ice sitting on Canada). This ice melt changed the density of the north Atlantic so turned off the gulf stream. I’ve heard about the gulf stream being switched off before but never realised how exceptional this current is. The Atlantic is unique among the oceans in transporting a huge amount of heat from the southern hemisphere to the north by Thermo-haline Circulation. When you look at what the temperature did around Europe when this switched off (the so called heinrich event and Younger Dryas), it’s quite remarkable, the temperature plummets on the charts to a new floor for about 1000 years, like a pressed down piano key. Intriguingly this was matched by accelerated warming in the Southern Hemisphere as all the heat stopped being transported away. But I suppose the implication is that the southern hemisphere was being artificially cooled down all along – and is so even now. So I wonder what the temperature would become here in Australia if the gulf stream switched off tomorrow? The charts did not seem to show such an extreme effect as that suffered by Europe though, where the changes were quite localised. It was interesting to see also the effect of the de-gassing of the southern ocean – i don’t know why only the southern ocean does this.
The Lecture was over in the Leonard Huxley theatre. Next time I am over that way I will check out the big machine statue. I was just reading about it today. Dad always told me about how the whole physics building was full of wires for this thing, running along the corridors, to one of the largest homopolar generators ever built.
Philosophy was interesting this morning. We argued about immigration and I got a chance to argue for the idea that there should be no immigration restrictions at all. I’m aware that this policy would completely transform Australian society, but I reckon we would all be better off for it once the dust settled.