Record hot years almost certainly caused by man-made warming, study finds

A record-breaking string of hotyears since 2000 is almost certainly a sign of man-made globalwarming, with vanishingly small chances that it was caused byrandom, natural swings, a study showed on Monday.

Last year was the hottest since records began in the 19thcentury in a trend that almost all scientists blame on
greenhouse gases from burning of fossil fuels, which have been stoking heatwaves, droughts, downpours and rising sea levels.

"Recent observed runs of record temperatures are extremelyunlikely to have occurred in the absence of human-caused globalwarming," a U.S.-led team of experts wrote in the journalScientific Reports.

Written before 2015 temperature data were released, itestimated the chance of the record run with up to 13 of the 15warmest years all from 2000 to 2014 was between one in 770 andone in 10,000 if the series were random with no human influence.

• Heat record: 2015 was hottest year by huge margin

Lead author Michael Mann, a professor of meteorology atPennsylvania State University, told Reuters that the group's
computer simulations indicated those odds including 2015 hadwidened to between one in 1,250 and one in 13,000.

Climate change is real, human-caused and no longer subtle we're seeing it play out before our eyes," he wrote in an
e-mail. Natural variations include shifts in the sun's output orvolcanic eruptions, which dim sunlight.

"Natural climate variations just can't explain the observedrecent global heat records, but man-made global warming can,"StefanRahmstorf, a co-author from the Potsdam Institute ofClimate Impact, said in a statement.

The scientists tried to account for factors including thatheat from one warm year spills over into the next. And
temperatures in many years are almost identical, making it hardto rank their heat with confidence.

Last month, almost 190 nations agreed at a summit in Paristo the strongest deal yet to shift from fossil fuels towards
cleaner energies such as wind and solar power to limit warming.

Separately on Monday, the U.N.'s World MeteorologicalOrganization (WMO) confirmed U.S. and British data showing 2015was by far the hottest year on record and noted that a powerfulEl Nino event, warming the surface of the Pacific Ocean, hadstoked extra heat.

"The power of El Nino will fade in the coming months but theimpacts of human-induced climate change will be with us for manydecades," WMO Secretary-General Petteri Taalas said.

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