Yesterday, I did a short interview with Dennis Avery, a senior fellow at the Hudson Institute and the co-author of "Unstoppable Global Warming: Every 1500 Years."

Here's the edited transcript of the interview.

Now, your book is called, "Unstoppable Global Warming: Every 1500 Years." First of all, how do you know that we've had global warming every 1500 years or so and for how long has that been occurring?

Well, our records go back about a million years in ice cores and sea bed sediments and it seems to be a solar length cycle based on our records of sunspots that go back several centuries and the Carbon-14 and Beryllium-10, that are produced here on earth. The Carbon-14 and Beryllium-10 cycle -- they follow the 1500 year cycle as do our temperatures.

So basically you're saying global warming is caused by the sun, not human beings. Would that be correct?

That's correct and we have confirmation in history. We had Roman warming about the time of Christ (Hawkins' Note: If I am understanding Avery correctly, the last sun driven warming cycle before this one started about 200 BC and ran through roughly 350-400 AD). Then we had the cold dark ages. We had a warming in the 10th, 11th, 12th centuries. We had 650 years of the little ice age and now we're back warming again.

Tell us about when the greenhouse gasses started surging in this century and when the temperature went up. They didn't happen at the same time, did they?

Well, if this were a human caused warming, it should have started about 1940 and trended strongly upward as global industrialization followed World War 2. That isn't what happened. The warming started about 1850. We had a surge of warming from about 1850 to 1870. We had another surge from 1916 to 1940 and then, when the greenhouse gasses began to spew from the factories, the temperatures went down for 35 years. 1976 to 1998, we had another surge of warming, but we've had no warming in the last 8 years. So, what we have is an erratic warming that started too soon to be blamed on humans and is not following in the footsteps of the CO2 levels in the atmosphere.

Now, how much longer should we expect this global warming cycle to last and how much hotter should we expect it to get?

The typical warming has been 1 to 2 degrees Celsius. Some of them have been a bit warmer than that. The one about 5000 years ago was quite warm. Obviously, all of our wildlife species and plants have been through these cycles before and we haven't studied their coping strategies, but we know they have them because they're here.

And, we can't really predict how long this will last. The 1500 year cycle is very regular during the ice ages and it's less regular during the warmings, but we've probably got several hundred more years of warm, stable, sunny weather and then we'll have another icy age, either a little ice age or a big one, in which case, things will either get quite a bit colder or a whole lot colder and the weather will be cloudy and unstable and people will wish they were living in a warming.

If this is such a good explanation -- and it does seem to make sense -- why do you think there are so many scientists out there who say that man is responsible for global warming?

Well John, if people believe me, there wouldn't be 2 billion dollars a year in federal research grants to set-up computerized climate models, Greenpeace wouldn't be selling memberships to people terrified of warming, and Al Gore would have to get a real job.

(Laughs) That's it! ...Thank you for your time.