Rise of rainfall events linked to global warming

LONDON: The rise of rainfall events setting ever new records in the past 30 years is linked to rising global temperatures which are caused by greenhouse-gas emissions from burning fossil fuels, says a new study.

An advanced statistical analysis of rainfall data from the years 1901 to 2010 derived from thousands of weather stations across the globe show that over 1980-2010 there were 12 per cent more of these events than expected in a stationary climate, a scenario without global warming.

While before 1980, multi-decadal fluctuations in extreme rainfall events are explained by natural variability, the researchers detected a clear upward trend in the past few decades towards more unprecedented daily rainfall events due to the global warming.

Extreme rainfall in Pakistan in 2010 caused devastating flooding which killed hundreds and led to a cholera outbreak. Other examples of record-breaking precipitation events in the period studied include rainstorms in Texas in the US in 2010, which caused dozens of flash-floods.

And no less than three so-called ‘once-in-a-century’ flooding events in Germany which all happened in just a couple of years, starting 1997.

“In all of these places, the amount of rain pouring in one day broke local records — and while each of these individual events has been caused by a number of different factors, we find a clear overall upward trend for these unprecedented hazards,” said lead-author Jascha Lehmann from Potsdam Institute for Climate Impact Research in Germany.

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 per cent, in Europe 31 per cent, in the central US 24 per cent.

In contrast, some regions experienced a significant decrease of record-breaking daily rainfall events. In the Mediterranean, the reduction is 27 per cent, and in the Western US 21 per cent. Both regions are at the risk of severe droughts.