IPCC to Raise Warming Forecast, Exclude U.S. Model?

IPCC to Raise Warming Forecast, Exclude U.S. Model?
April 1, 1999



A scientific firestorm is brewing among distinguished dissenters and disenfranchised climate modelers amid rumors of major revisions to the United Nations' position on climate change.

With its next report due in 2001, the U.N. Intergovernmental Panel on Climate Change (IPCC) reportedly plans to increase its estimate of twenty-first century warming. To support that forecast, the IPCC will restrict--to somewhere around three--the number of climate models it relies on.

The IPCC says its increased forecast is justified because it now believes that sulfate aerosols--which originate largely from the combustion of coal for power production--will be removed from the atmosphere faster than they thought.

Sulfate aerosols are said by the IPCC to explain the now-acknowledged failure of the original climate models, which, according to the group's 1995 report, "tended to predict too much warming."

But sulfate aerosols offer a poor explanation for what has happened in the last two decades. Removing them from the models will only make those models less accurate.



Selective Modeling

Though 33 climate models exist today, the IPCC is planning to limit its next report's "modeling" section to just three.

Choosing just three models means 30 modeling groups will be ignored. Each employs dozens of people, who are left to explain to their funders and employers--government officials and university presidents among them--why their work is being ignored.

One of the models not chosen by the IPCC is a new one from the U.S. National Center for Atmospheric Research (NCAR). The NCAR model is one of the most "transparent" available, accessible to any and all researchers with sufficient funds to work with it.

The NCAR model predicts just 2.3 degrees C of warming if atmospheric carbon dioxide levels are doubled, and just 1.3 degrees C of warming over the next century if realistic greenhouse-effect changes are modeled.


Excerpted from the March 1 issue of World Climate Report, a biweekly research review published by New Hope Environmental Services, P.O. Box 455, Ivy, VA 22945; e-mail wcr@nhes.com. The full text of World Climate Report is available on the Internet at http://www.nhes.com.