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Global warming: New statistical analysis trys to pinpoint temperature increases by region and season

Ohio State statisticians try to reconcile different climate models

How hot will it get? Image courtesy NASA.

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.

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2 Responses

  1. Regardless of whether global warming is anthropogenic or not is irrelevant. Yes, the climate changes, and even drastically. The problem is that the current warming period is occuring in a radically different environment. Previous high warming periods produced huge swathes of dense vegetation. A LARGE majority of carbon in the environment was in living biomass- possibly the largest living carbon biomass before or since. The vegetation was producing so much oxygen that it allowed giant land arthropods to exist. Much of this biomass died and was buried. The carbon was still contained in biomass- just dead biomass. This insane amount of vegetation stayed buried for millions of years until it was converted into oil and coal. At this point the carbon is still locked out of the atmosphere. Fast-forward to the Industrial Revolution. We began to burn coal and later oil which released this carbon into the atmosphere as CO2. More of the biomass got trapped in lakes and ponds that froze over during the last Ice Age and sank to the bottom to undergo anaerobic oxidation, forming methane, CH4. Now the tundra lakes and ponds are warming up. They are so warm that they are “boiling”- releasing copious amounts of CH4. BTW, CH4 is ***20x*** as potent a greenhouse gas as CO2. In addition, we are cutting down forests left and right. Forests are good at removing CO2 from the air. We are rapidly approaching a feedback loop where as the earth warms, more greenhouse gasses are released causing more warming… The warmest known period since life appeared on earth was at the end of the Permian. This warming period also occurred at the same time as the greatest extinction event EVER. Hmmm…

    • To justwondering:
      Ascribing blame to AGW may be an irrelevant exercise, given the precipitous environmental changes currently projected using RCMs to reach a consensus climate estimate. Presumably the etiology is pointless during — and in the aftermath of — a cascade of positive feedbacks precipitated by human-induced climate forcings. Perhaps we have already reached (and caused) a critical threshold in the eco-system. I suspect our eco-system tipping point occurred decades ago, before conspicuous ‘squealing’ became evident.

      In my own lifetime, our human population has tripled. How can anyone not infer from this perilous fact alone, despite technological expedients and presumably because of them, that Mommy Nature would not bite back?

      I have no academic/scientific qualifications to make verifiable assertions; merely a limited understanding of others’ professional observations, in addition to my own faculties of observation. Nevertheless, a detailed analysis of AGW is relevant to me, in as much as I want people to become increasingly aware of our impact before and while cataclysmic events unfold. I don’t want to see these events attributed to antiquated apocalyptic prophesies. It’s a subjective relevance, even if saying ‘I told you so’ won’t matter much in the long run.

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