Regional insights set latest study of climate history apart

Space Daily via SPX: As climate studies saturate scientific journals and mainstream media, with opposing viewpoints quickly squaring off in reaction and debate, new findings can easily be lost in the noise. But in the case of Northern Arizona University Regents' professor Darrell Kaufman and a study appearing in Nature Geoscience, obscurity is an unlikely fate.

What Kaufman-the lead co-author of "Continental-scale temperature variability during the last two millennia"-and 78 experts from 24 countries have done is to assemble the most comprehensive study to date of temperature change of Earth's continents over the past 1,000 to 2,000 years. By looking regionally, the researchers found considerable complexity hidden within a global average.

"We wanted a new and ambitious effort to reconstruct past climate," Kaufman said of the PAGES 2k network of researchers. "One of the strongest aspects of the consortium study is that it relies on regional expertise."

Members of the consortium represent eight continental-scale regions. They lent their insights about the best proxy records-such as tree-ring measurements-to use for a particular region, and how to interpret the data based on regional climatology.

While the study does not attempt to attribute temperature changes to natural or human-caused factors, Kaufman said the finding of a long-term global cooling trend that ended late in the 19th century is further evidence that increased greenhouse gasses have had an influence in later years. "The pre-industrial trend was likely caused by natural factors that continued to operate through the 20th century, making 20th century warming more difficult to explain if not for the likely impact of increased greenhouse gasses," Kaufman said.

While that sounds like a familiar theme, the study's findings of regional variations are less well known. Because of extensive participation by scientists working in the Southern Hemisphere, Kaufman said, data from those regions broadened what had been a view previously centered on Europe....

A NASA image of Europe processed by http://www.terraprints.com, Wikimedia Commons, Wikimedia Commons, under the Creative Commons Attribution 2.5 Generic license