Friday, August 21, 2009

Climate Change Modeling Tools

The tools used to determine climate change by the United Nations Intergovernmental Panel on Climate Change were recently applied to a previous warming period, and the results indicate we may, wisely, step back from basing too many major policy decisions—especially those impacting our struggling economy—on their conclusions.

An excerpt from the article by Pacific Research Institute.

“A recent study of paleoclimate, the results of which appear in the August issue of Nature Geoscience, finds that today’s climate models do not accurately predict the most similar previous episode of climate warming in the geologic record. While this should not cast doubt on the value of climate models in tools to analyze drivers and projections of climate change, the study does point out that our understanding of climate dynamics remains imperfect.

“The authors of the study, Carbon dioxide forcing alone insufficient to explain Palaeocene–Eocene Thermal Maximum warming, include Richard E. Zeebe of the School of Ocean and Earth Science and Technology, Department of Oceanography, University of Hawaii at Manoa; James C. Zachos of the Earth and Planetary Sciences Department, University of California, Santa Cruz; and Gerald R. Dickens of the Department of Earth Sciences, Rice University. Their research focused on the models used by the Intergovernmental Panel on Climate Change (IPCC) to generate climate projections.

“In an analysis of proxy climate data from the geologic ocean sediment records, the researchers studied the ability of these models to replicate the warming observed during the Palaeocene–Eocene Thermal Maximum (PETM), a period of 5-9 degree C warming that occurred about 55 million years ago. The researchers found that the models predicted only about half of the observed warming, indicating that an additional mechanism, beyond carbon dioxide concentrations, was responsible for a significant amount of the warming during that period.

“The PETM was not, of course, exactly the same sort of conditions we have today. Conditions at the beginning of the warming trend were different, with initial CO2 concentrations strikingly higher, for reasons that are not known. For the most part, there were no large amounts of ice on the earth’s surface during the PETM, and the energy dynamics of ice are significant. Nonetheless, the inability of the climate models adequately to capture a previous episode of climate change does suggest that our models are missing potentially key relationships.”