Ohio State statisticians try to reconcile different climate models
By Summit Voice
SUMMIT COUNTY — Average temperatures in the Rocky Mountains could soar by more than 6 degrees in the summer and 4 degrees in the winter in the next few decades, according to a new statistical analysis of climate models by researchers at Ohio State University.
The Hudson Bay region will likely experience the largest temperature swings, especially in the winter. Temperatures could rise an average of about 10.7 degrees, possibly because meting ice will reduce the region’s albedo. In the summer, the Hudson Bay region might only see average temperatures rise by about 2 degrees, the scientists said after fine-tuning a sophisticated climate model that helps narrow the gap between previous predictions.
The analysis examines groups of regional climate models, finds the commonalities between them, and determines how much weight each individual climate projection should get in a consensus climate estimate. Through maps on the statisticians’ website, people can see how their own region’s temperature will likely change by 2070 – overall, and for individual seasons of the year.
“One of the criticisms from climate-change skeptics is that different climate models give different results, so they argue that they don’t know what to believe,”said Noel Cressie, professor of statistics and director of Ohio State’s Program in Spatial Statistics and Environmental Statistics.
“We wanted to develop a way to determine the likelihood of different outcomes, and combine them into a consensus climate projection,” Cressie said. “We show that there are shared conclusions upon which scientists can agree with some certainty, and we are able to statistically quantify that certainty.”
For their initial analysis, Cressie and Kang chose to combine two regional climate models developed for the North American Regional Climate Change Assessment Program. Though the models produced a wide variety of climate variables, the researchers focused on temperatures during a 100-year period: First, the climate models’ temperature values from 1971 to 2000, and then the climate models’ temperature values projected for 2041 to 2070. The data were broken down into blocks of area 50 kilometers (about 30 miles) on a side, throughout North America.
Averaging the results over those individual blocks, the statistical analysis estimated that average land temperatures across North America will rise about 4.5 degrees by 2070. That result is in agreement with the findings of the United Nations Intergovernmental Panel on Climate Change.
Cressie cautioned that this first study is based on a combination of a small number of models. Nevertheless, he continued, the statistical computations are scalable to a larger number of models. The study shows that climate models can indeed be combined to achieve consensus, and the certainty of that consensus can be quantified.
The statistical analysis could be used to combine climate models from any region in the world, though, he added, it would require an expert spatial statistician to modify the analysis for other settings.
- Global warming: Extreme summer highs expected frequently (summitcountyvoice.com)