Floods in Pakistan ‘probably’ worsened by warming

Floods in Pakistan ‘probably’ worsened by warming

floods in pakistan

floods in pakistan

Global warming may have played a role in the devastating floods that hit Pakistan, scientists say.

Researchers from the World Weather Attribution group say climate change may have increased rainfall intensity.

However, there were many uncertainties in the results, which prevented the team from quantifying the magnitude of the impact.

The scientists think there is about a 1% chance of such an event happening in the coming year.

Tens of millions of people have been affected in the two months since the floods began in Pakistan, with about 1,500 killed in rising waters.

The intensity of the downpours caused the Indus River to burst its banks, while landslides and urban flash floods inundated many areas.

From the outset, politicians pointed out that climate change has been a major contributor to the desperate scenes.

But this first scientific analysis says the picture is complex.

Certainly, the crippling heatwaves that gripped India and Pakistan earlier this year were easier to attribute, with researchers finding that climate change made them up to 30 times more likely to happen.

But extreme rainfall is difficult to assess. Pakistan is on the edge of the monsoon region, where the rainfall pattern is extremely variable from year to year.

Map showing damage caused by monsoon rains

Map showing damage caused by monsoon rains

Other complications include the impact of large-scale weather events such as La Niña, which also played a role in the last major floods in Pakistan in 2010.

During the 60-day period of heaviest rainfall this summer, scientists have recorded an increase of about 75% over the Indus basin, while the heaviest five-day period over the provinces of Sindh and Balochistan recorded an increase in rainfall of about 50%.

The researchers then used climate models to determine how likely these events would be in a world without warming.

Some models indicated that the increase in rainfall intensity could all be due to human-induced climate change, but there were significant uncertainties in the results.

“Our evidence suggests that climate change played an important role in the event, although our analysis does not allow us to quantify how large the role was,” said Friederike Otto of Imperial College London, one of the authors of the report.

“What we saw in Pakistan is exactly what climate projections have been predicting for years. It also matches historical data showing that heavy rainfall in the region has increased dramatically since humans emit large amounts of greenhouse gases into the atmosphere. And our own analysis also shows clear that further warming will intensify these episodes of heavy rainfall.”

“So while it’s difficult to give a precise figure for the contribution of climate change, the fingerprints of global warming are clear.”

The researchers say that the heavy rainfall that Pakistan has endured this year now has about a 1% chance of coming back in any given year, although this estimate also comes with a host of uncertainties.

Follow Matt on Twitter @mattmcgrathbbc.

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