Richard Lindzen

And if you're at a point where it doesn't melt, you build a glacier.

It takes thousands of years, but eventually it's big.

And in recent years, for instance, there have been young people who have

shown that that works.

It's interesting, there was even a national program called Climap to study this.

It's around 1990 or so.

And they found something peculiar.

They found that there were peaks in the orbital variables that were found in the data for ice volume.

but that the time series were not lining up right.

The young people looking at this said, you're looking at the wrong thing.

If you're looking at the insulation, you want to look at the time rate of change of ice volume, not just the ice volume.

And then the correlations were excellent.

So this was a theory, Milankovitch, that I think is

reasonably sustained.

But the people doing this got no credit, nothing, because early in my career these people would have been rewarded.

Now it didn't contribute to global warming.

Nobody pays attention to it.

What's special about the recent ice ages is they're pretty periodic.

So for 700,000 years, almost every 100,000 years, you have a cycle.

If you go back further than that, you begin seeing that fall apart.