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.
I want to spend a couple of minutes outlining the fundamentals of climate change.
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?
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.
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
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
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