2017's Extreme Heat, Flooding Carried Clear Fingerprints of Climate Change

https://insideclimatenews.org/news/10122018/extreme-weather-climate-attribution-lucifer-heat-wave-harvey-flooding-ams-study

By John H. Cushman Jr.
Dec. 10, 2018

Many of the world's most extreme weather events witnessed in 2017, from Europe's "Lucifer" heat wave to Hurricane Harvey's record-breaking rainfall, were made much more likely by the influence of the global warming caused by human activities, meteorologists reported on Monday.

In a series of studies published in the American Meteorological Society's annual review of climate attribution science, the scientists found that some of the year's heat waves, flooding and other extremes that occurred only rarely in the past are now two or three times more likely than in a world without warming.

Without the underlying trends of global climate change, some notable recent disasters would have been virtually impossible, they said. Now, some of these extremes can be expected to hit every few years.

For example, heat waves like the one known as "Lucifer" that wracked Europe with dangerous record temperatures, are now three times more likely than they were in 1950, and in any given year there's now a one-in-10 chance of an event like that.

In China, where record-breaking heat also struck in 2017, that kind of episode can be expected once every five years thanks to climate change.

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Martin Hoerling, a NOAA researcher who edited this year's collection, said the arrival of these damages has been forecast for nearly 30 years, since the first IPCC report predicted that "radical departures from 20th century weather and climate would be happening now."

Not every weather extreme carries the same global warming fingerprint. For example, the drought in the U.S. High Plains in 2017, which did extensive damage to farming and affected regional water supplies, chiefly reflected low rainfall that was within the norms of natural variability—not clearly a result of warming.

Even so, the dry weather in those months was magnified by evaporation and transpiration due to warmer temperatures, so the drought's overall intensity was amplified by the warming climate.

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Attribution studies should not just place the blame on pollution-driven climate change for increasingly likely weather extremes, the authors said. They should help society "better navigate such unprecedented extremes."

tags: extreme weather, severe weather