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World's Weather Now Has a New Normal July 25, 2014
Tornado and lightning
Weather has been so altered by climate change over the past few decades that the old "normal" calculations from 1961 through 1990 are no longer representative.
The U.N.’s weather agency says the baseline for what is considered “normal” in weather needs to be adjusted to account for atmospheric shifts caused by global warming.

The World Meteorological Organization (WMO) announced that the 30-year period most often used as a yardstick for climate — 1961 to 1990 — is no longer a useful tool for gauging today’s climate.

Such 30-year “normals” are typically updated every three decades, but the WMO argues that’s not often enough.

A press release from the agency urges weather agencies to now use the 1981-2010 climate baseline for predicting temperatures and rainfall, and for recommending crop planting times.

While the United States already does this, the WMO says other domestic weather services should also begin updating their climate baselines every 10 years.

Photo: NOAA