Let's talk about climate models. Specifically, let's talk about the climate models that attempt to predict the future temperature of the planet.

But before we do, it's important that you know a little bit about me.

I'm a physicist. I taught at Columbia University and then at Princeton for five decades.

I've published over 200 peer-reviewed scientific papers.

I have co-authored several books, including one of the first on how a carbon dioxide emissions CO2 affects the climate.

I served as the director of the Office of Energy Research at the U.S. Department of Energy.

And before that, I invented the sodium guide star which is still used on most big astronomical telescopes

to measure and correct for atmospheric turbulence, that is, for the unpredictable movement of air and water.

This turbulence blurs the images of stars and other space objects.

One more thing. I cared deeply about the environment. We live on a beautiful planet.

I want to keep it that way. I've spent a lot of time working to do just that.

In short, I know a lot about the Earth's atmosphere and climate. I also know a lot about long-term predictive climate models.

And I know they don't work. They haven't worked in the past. They don't work now.

And it's hard to imagine when, if ever, they'll work in the foreseeable future.

There's a common sense reason for this. Aside from the human brain, the climate is the most complex thing on the planet.

The number of factors that influence climate, the sun, the Earth's orbital properties, oceans, clouds, and, yes, industrial man,

is huge and enormously variable. Let me try to narrow this down. For the purposes of illustration, let's just focus our attention on water.

The Earth is essentially a water planet. A major aspect of climate involves a complicated interaction between two very turbulent fluids,

the atmosphere, which holds large amounts of water, think rain and snow, and the oceans which cover fully 70% of the Earth's surface.

We can't predict what effect the atmosphere is going to have on future temperatures because we can't predict cloud formations,

and the convection of heat, oxygen, salt, and other quantities that pass through the oceans, not to mention weather cycles like El Nino in the tropical Pacific,

make predicting ocean temperatures and equally difficult business.

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