A recent letter writer (“Climate change truth and consequences”) critiquing John Carlson’s commentary on these pages ignores several salient facts.
He expresses concern about the warming due to the “insulating effects” of current CO levels (an increase of 35 percent from the “historically high” levels of 200 years earlier). He neglects to mention that CO2 currently constitutes about .038 percent of the atmosphere, an increase of about .004-005 percent over the last 60 years. During the first 30 years of this relatively modest increase, temperatures went down, prompting climatologists then to warn of a CO2 induced “ice age.”
His reference to the Nature article predicting cooling over the next 10-15 years neglects to mention that the cooling is attributed to normal cyclical variations in solar radiation. The anticipated increased temperatures beyond that period are due to the gradual increases in long-term solar activity. Neither of these phenomena have anything to do with CO2 levels.
The writer recommends that readers refer to the IPCC report. I strongly concur.
Section 2 of the “Summary for Policymakers” of this report says “Observed patterns of warming and their changes are simulated only to be models that include anthropogenic (i.e. CO2) forcings.” In other words climatologists’ global temperature sensitivity to CO2 are based on the fact that their computer model results without CO2 (their “natural forcing model”) didn’t agree with measured temperatures from 1980-2000.
The IPCC report shows their natural forcing models “assumed” solar variations had little effect on global temperatures (about 1/10th that of anthropogenic gases). Others (e.g. artr@oism.org) have shown very good correlation between solar activity and global temperatures for the last 150 years, suggesting a far stronger influence.
Increasing the solar activity function in the “natural forcing” model would reduce the temperature discrepancies between the model and measured data, reducing the need to apply some effect for CO2. The reduced CO2 forcing function would result in future temperature predictions far less sensitive to emissions and minimize the need for future dramatic reductions.
Bill Hirt
Bellevue
