Pakistan floods ‘likely’ made worse by warming

floods in pakistan

Global warming is likely to 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 the intensity of rainfall.

However, there were many uncertainties in the results, so the team was unable to quantify the scale of the impact.

Scientists believe that there is about a 1% chance of such an event occurring in the next year.

In the two months since the floods began in Pakistan, tens of millions of people have been affected, and around 1,500 have died from rising waters.

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

From the beginning, politicians pointed out that climate change had contributed significantly to the desperate scenes.

But this first scientific analysis says the picture is complex.

Certainly the devastating heat waves that hit India and Pakistan earlier this year were easier to blame, as researchers found that climate change had made them up to 30 times more likely to happen.

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

Map showing damage from monsoon rains

Map showing damage from 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 flooding in Pakistan in 2010.

During the heaviest 60-day period this summer, scientists recorded an increase of around 50% in the Indus River Basin, while the heaviest five-day period in Sindh and Balochistan provinces saw an increase in about 75% precipitation.

The researchers then used climate models to determine the probability of these events occurring in a world without warming.

Some of the models indicated that increases in rainfall intensity could be due to human-caused climate change; however, there were considerable uncertainties in the results.

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

“What we saw in Pakistan is exactly what climate projections have been predicting for years. It is also in line with historical records that show heavy rainfall has increased dramatically in the region since humans started emitting large amounts of greenhouse gases. greenhouse gas into the atmosphere. And our analysis also clearly shows that further warming will make these heavy rain events even more intense.”

“So while it’s hard to put a precise figure on the contribution of climate change, the fingerprints of global warming are clear.”

Researchers say the heavy rains Pakistan experienced this year now have about a 1% chance of recurring in any given year, although this estimate also carries a wide range of uncertainty.

Follow Matt on Twitter @mattmcgrathbbc.

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