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climate shifts

Surprises from Past Could Spell Longer Droughts, Rising Sea Levels

Abrupt climate changes could lead to decade-long droughts and massive sea-level rise, according to a University of Arizona geoscientist who studies the climate of the distant past. Factors that influence the climate system, such as natural changes in the Earth’s orbit or rising carbon dioxide emissions from cars and power plants, can result in dramatic climate shifts, says Jonathan Overpeck, a professor of geosciences and director of the UA Institute for the Study of Planet Earth. Scientists studying natural climate records, such as the variations in tree rings and gas bubbles trapped in the polar ice caps, find ample evidence of these types of rapid changes in the past — sometimes occurring in a decade or less.

Large-scale climate changes occur naturally, new research says

A Canadian researcher has found new evidence that — contrary to previous belief — the past 6,000 years have been marked by large-scale climate changes occurring naturally, on a regular basis. He and his research team have documented four abrupt climate shifts over the past 5,500 years in western Canada, occurring on average every 1,220 years. Until now the last 6,000 years has been considered climatically stable, with the main evidence of large-scale shifts being found in the Greenland ice cores and sediments from the Atlantic Ocean. The team’s findings are reported in the current issue of the Proceedings of the National Academy of Sciences.