Heavy rainfall events setting ever new records have been increasing strikingly in the past thirty years. While before 1980, multi-decadal fluctuations in extreme rainfall events are explained by natural variability, a team of scientists of the Potsdam Institute for Climate Impact Research detected a clear upward trend in the past few decades towards more unprecedented daily rainfall events.
They find the worldwide increase to be consistent with rising global temperatures which are caused by greenhouse-gas emissions from burning fossil fuels…
The average increase is 12 percent globally – but 56 percent in South East Asia
An advanced statistical analysis of rainfall data from the years 1901 to 2010 derived from thousands of weather stations around the globe shows that over 1980-2010 there were 12 percent more of these events than expected in a stationary climate, a scenario without global warming. “Due to the upward trend, the worldwide increase of record-breaking daily rainfall events in the very last year of the studied period reaches even 26 percent”, Lehmann adds.
The record-breaking anomaly has distinct patterns across Earth’s continents with generally wet regions seeing an over-proportional increase and drier regions less so. In South East Asian countries the observed increase in record-breaking rainfall events is as high as 56 percent, in Europe 31 percent, in the central US 24 percent. In contrast, some regions experienced a significant decrease of record-breaking daily rainfall events. In the Mediterranean, the reduction is 27 percent, and in the Western US 21 percent. Both regions are at risk of severe droughts.
While a statistical analysis of course cannot provide direct physical cause-effect relations, the scientists compared their findings to existing knowledge about how much more water can be stored in the atmosphere when temperatures rise, as given by the well-known Clausius-Clapeyron equation. This additional moisture can be released during short-term heavy rainfall events. The scientists show that the observed increase in unprecedented heavy rainfall events generally fits with this thermodynamically expected increase under global warming…
Up to now, studies could add up to only medium confidence on how human induced greenhouse gases have contributed to changes in heavy precipitation events at the global and regional scale. The new analysis now helps to fill this research gap. Building on previous work on extreme precipitation, it is the first to study worldwide observational data of record-breaking daily rainfall events in this context.
I probably haven’t said this for at least 10 minutes, but — if I was starting out, today, I’d point myself at a geek career in computational analysis. This stuff is fascinating. Most particularly when you have the opportunity to gather wide-reaching data and spend time data-mining, winnowing away the chaff – perhaps discovering a new direction, insight to old problems.