Ice Age

The distinguishing characteristic of human beings is versatility. Some animals run faster, some are better swimmers, some have better teeth and claws for killing and eating meat, some have better teeth and digestive systems for eating plants, and so on. But people do a little bit of everything quite well.

Finally, in Climate and Time he pointed out that there is yet a third astronomical influence on climate, which really ought to be taken into account. The tilt of the Earth’s axis (the amount it leans out of the vertical) also varies as time passes,

The obvious candidate for that something else was the way water gets locked up in great ice sheets during an Ice Age. When water evaporates, it is easier for the lighter molecules to escape into the air, so the water left behind tends to have a higher proportion of oxygen-18; much of the evaporated water, relatively rich in oxygen-16 compared with

The isotope technique, it was now clear, gave you, in effect, a measure of the global average temperature, no matter where in the oceans the core had been drilled. But they still needed a way to date accurately the temperature fluctuations that were now clearly apparent in the cores covering the entire Pleistocene Epoch.

Milankovitch reckoned that he started out on the task, when he was thirty-two years old, at exactly the right time: Had I been somewhat younger I would not have possessed the necessary knowledge and experience... Had I been older I would not have had enough of that self-confidence that only youth can offer.

The changes resulting from Arctic warming would be bigger than you might expect at first sight, and would in many ways be unpredictable, because of the effect of positive feedback. Today, the shiny white surface of the ice covering the Arctic Ocean reflects away incoming solar energy, and helps to keep the polar region cool. Once the ice starts to

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

Put all of the evidence together, and it tells us that a forest-dwelling East African proto-ape line gave rise to three separate lines, leading to ourselves, the chimpanzees and the gorillas, between about 3.5 and 4 million years ago, exactly when the climate was changing dramatically. Since both the Ice Ages and the evolutionary changes are tied t

As we mentioned earlier, given the present day geography of our planet—the distribution of the continents and oceans—the natural state of the Earth is in a full Ice Age. Koppen was correct in highlighting the importance of summer warmth in influencing the advance and retreat of the ice in the Northern Hemisphere. But, in a sense, he, too, got the a