Lecture 42

Lecture 42 - Lecture 42 Kyoto protocol Law of the sea...

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Lecture 42: Kyoto protocol; Law of the sea; energy supplies Today I want to discuss two main points: first, the issue of climate change, and second, international governance of air quality, which will largely be concerned with the Kyoto Treaty and the successors to it. Climate change I want to spend a couple of minutes outlining the fundamentals of climate change. The first set of questions has to do with whether the climate is changing, whether the change is caused by humans, and what sort of change we can expect. how much. The answer to the first question is yes, we can safely say that the climate is changing, and on different time scales–the decade, the century, the millennium, and the tens of millennium. In fact, I want to start with the large time scale, for reasons you’ll soon see. I’m sure you all know that we’ve had a series of Ice Ages. Just as a not-for-credit test, let me draw this big sine-shaped curve. The time scale is in the tens of thousands of years, but I won’t give the exact wave-length now. Suppose Point 1 is the depth of the Ice Age, Point 2 is partway up, Point 3 is well on the way up, Point 4 is as warm as it ever gets, Point 5 is starting to cool down, Point 6 is well down on the way to another Ice Age, and so back to Point 1, the depths of the second Ice Age. I don’t suppose anybody thinks we’re at the bottom of an Ice Age now, but how many think we’re around Point 2? How many think we’re near 3? How about Point 4? Point 5? Point 6? The answer is Point 5. Point 1, the last Ice Age, was about 30 or so thousand years ago, and Point 4, as warm as it gets, is the so-called Holocene Maximum of 7,500 or so years ago. So from bottom to top is about 23,000 years, and 7,000 years past the last maximum puts us about one-third of the way toward to bottom. So far, I’ve assumed that these are regular curves. They’re not. The amplitude varies from one cycle to the next, and so does the wave length. Not only that, the curve itself is not smooth. This big cycle has lots of up and down variation, say on the time scale of a millennium for shorthand, and the millennial ups and downs have ups and downs of their own, say on the century scale. Evidence for climate change . This point is important when we consider the evidence for climate change. The statement is made that the earth has been warming “for as far back as records go,” records meaning recorded contemporaneous observations. How far back is that? The oldest recoded observations go back two centuries or so. Records show that the earth has been getting warmer for the past 100 or 150 years, and this variation is generally believed to be related to the fact that, ever since the beginning of the industrial age, human beings have been pumping more and more carbon dioxide and other byproducts of combustion into the atmosphere. These gases have the property of retaining heat energy rather than allowing it to radiate back into space, so that, the more such gases an atmosphere contains, the warmer it and
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Lecture 42 - Lecture 42 Kyoto protocol Law of the sea...

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