Richard Lindzen

It turns out very poorly.

Because most climate change, by that definition, is regional.

So, for instance, in this area, let's say the states like Louisiana, Alabama, Gulf states, they had a period of cooling when the rest of the country was warming.

Nobody paid much attention to it because that's normal.

Different areas do different things.

You have reasons why it's local.

I mean, if you're near a coast, near a body of water, the circulations in the ocean are bringing heat to the surface and away from the surface all the time on time scales ranging from a few years for El Nino and so to a thousand years.

And so this has nothing to do with the global average.

The whole business that the global average is at issue was something that was created for people studying different planets.

And so you'd look at the average for each planet, and that varied quite a lot, so it was useful.

But for looking at the Earth's climate, I'm not sure a global mean is a particularly useful device.

You know, that's something there's argument about.

I think, you know, for instance, a man called Milankovitch around 1940 made a convincing argument.

And I think now it's correct.

that orbital variations created a change in insulation, incoming sunlight, in the Arctic in summer.

And that controlled the ice ages.

And the thinking was pretty simple.

He was saying that every winter is cold.

Every winter has snow.

But what the temperature or the insulation or the sunlight in the summer is determines whether that snow melts or not before the next cycle.