IH: Dr. Rapp, I presume you saw my review of your book (in our January and February issues), and I wanted to know if you felt we should clear up anything that might have given the audience an incorrect impression of your scientific opinions.
DR: I thought you had some of it, but it wasn’t quite gelled. Basically, the issues are these:
- Climate is never constant, even in the absence of human intervention.
- Over the past 130 years, the earth has warmed, although not continuously, and the warming varied with latitude.
- Over the same period, CO2 gradually increased due to human intervention.
- The alarmists believe that rising CO2 caused the warming based on two premises: (a) they claim that temperatures have been flat and stable for 2,000 years and then suddenly jumped up in the past 130 years just when CO2 was rising; (b) climate models indicate that CO2 causes warming. Thus, they say that the warming of the past century is outside the scope of natural variation.
- My reading of the proxy literature indicates that natural variations were significant, that temperatures were not flat and stable for 2,000 years, and variations of the past 130 years are within the scope of past natural changes. Also, I don’t assign much credibility to climate models.
DR: I don’t think so. I’ve looked at a lot of those e-mails, and I think they were concerned with recent temperature drops where the persistent temperature rises seemed to have dropped out. Over the last 10 years we’ve had oscillations in temperature, but there’s been no net increase in temperature. I think that’s what they were mostly hiding. They didn’t want the public to see that the temperature seems to have flattened out. But in fairness to them, I don’t think a 10-year period proves very much in climate science, so it still doesn’t prove them wrong.
I believe the “hockey stick” is technically and scientifically totally wrong. The data is too noisy, and when you add up the signals, you get zero. I don’t believe that we really know very accurately how the temperature varied over the last 2,000 years. I just don’t think that their rendition can be believed. In climatology, there’s a lot of fuzzy stuff. It’s not like particle physics.
IH: And what about the second premise relied upon by the climate community?
DR: The second major support of the alarmist position is the use of climate models. Climate models predict that as CO2 increases, the earth is going to warm. All the climate models end up with a two-step temperature rise. The first step is the CO2 itself absorbs some of the infrared energy emitted by the earth and deposits that heat into the atmosphere, which produces a temperature rise. Then, as the earth warms, more and more water evaporates from the waters of the earth, and water vapor is a more powerful greenhouse gas than CO2 itself. So, when there’s more water vapor on average in the atmosphere, you get more heating. Now, of the two steps, the water vapor step is actually bigger than the CO2 step.
There are several problems with all this. Estimating the first step, the CO2 effect, is very complicated. It’s not just simply that we’ve got more CO2 and it absorbs radiation. It actually depends on the distribution of CO2 with altitude. So, the first point of doubt about the modeling is that the modeling of CO2 itself is complicated.