Floods in Pakistan “probably” worsened by warming

Floods in Pakistan “probably” worsened by warming

floods in Pakistan

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 rainfall intensity.

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

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

In the two months following the start of the floods in Pakistan, tens of millions of people were affected and about 1,500 died as a result of rising waters.

The intensity of the downpours has seen the Indus River break its banks, while landslides and urban floods have engulfed many areas.

From the start, politicians have pointed to climate change as a significant 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 had made them up to 30 times more likely.

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

Map showing the damage caused by monsoon rains

Map showing the damage caused by monsoon rains

Further 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 wettest 60-day period this summer, scientists recorded an increase of about 50% on the Indus River basin, while the most intense five-day period in Sindh and Baluchistan provinces recorded an increase in rainfall of about 75%.

The researchers then used climate models to determine the likelihood that these events would have been in a world without warming.

Some of the models indicated that the increase in rainfall intensity could be due to human-caused climate change, however 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 report’s authors.

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

“So while it is difficult to pinpoint the contribution of climate change, the fingerprints of global warming are evident.”

The researchers say the heavy rains Pakistan has experienced this year are now about 1% likely to recur in any given year, although this estimate also has a wide range of uncertainties.

Follow Matt on Twitter @mattmcgrathbbc.

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