Ice Age

Kukla had not invented this technique, although he was one of the first people to apply it to the study of past climates. It depended upon the discovery that the Earth’s magnetic field is not constant, but sometimes (seemingly at random) reverses itself entirely, first fading away to nothing and then building up again in the opposite sense, so that

when more water is locked up in ice, the sea level falls; but when the ice sheets melt, sea level rises.

Coffee (black) was served by Milankovitch’s wife promptly at ten o’clock, and occupied just ten minutes before it was back to work. Lunch at one was followed by a short siesta and a cigar, then more calculations until six, when work ceased for the day. A stroll before dinner, which was a leisurely meal taken at eight, where the family discussed the

Since the temperature at the bottom of the sea hardly changes, even during the switch from an Ice Age to an Interglacial, this was the definitive proof that the main influence on the oxygen isotope composition was indeed the advance and retreat of the ice sheets on land, and that the isotopes were recording the pulsebeat of global climate change.

They depend simply on the amount of heat which is required to turn ice at 0°C into water at the same temperature—the latent heat of fusion, which is (in the units used by Mason) 80 calories for every gram of ice melted. Since one calorie is defined as the amount of heat needed to raise the temperature of one gram of water by one degree Celsius, thi

A similar process operates in reverse when water vapour condenses into liquid or water freezes into ice. In each case, latent heat is given out by the water, rather than being taken up. When the vapour condenses into water at the same temperature, 595 calories of heat are released for each gram involved; so when the vapour goes all the way to the s

it was while watching the fighting that he suddenly had a flash of insight which showed him the way around the mathematical logjam that had been holding him up. It was a classic example of the way the answer to a problem you have been struggling with can pop into your head once you stop looking for the solution.

When reversals happen, they take place in less than 10,000 years (perhaps much less), so they show up sharply in the geological record; but once a particular orientation of the field is established, it may last for millions of years, or only for a few tens of thousands of years. The most recent reversal happened about 780,000 years ago, but the Ear

But it was Koppen who pointed out that it is always cold enough for snow to fall in the Arctic in winter, even today, and that the reason that the Northern Hemisphere is not in the grip of a full Ice Age at present is because the ‘extra’ snow melts away again in summer. He reasoned that the way to encourage the ice to spread would be to have a redu