Study: It’s likely a warmer world worsened deadly Dubai downpour

Circumstantial evidence points to climate change as worsening the deadly deluge that just flooded Dubai and other parts of the Persian Gulf, but scientists didn’t discover the definitive fingerprints of greenhouse gas-triggered warming that they have seen in other extreme weather events, a new report found.

Between 10 percent and 40 percent more rain fell in just one day last week — killing at least two dozen people in the United Arab Emirates, Oman and parts of Saudi Arabia — than it would have in a world without the 1.2 degrees Celsius (2.2 degrees Fahrenheit) warming that has come from the burning of coal, oil and natural gas since the mid-19th century, scientists at World Weather Attribution said Thursday in a flash study that is too new to be peer-reviewed.

In at least one spot, a record 11 inches of rain fell in just 24 hours, more than twice the yearly average, paralyzing the usually bustling city of skyscrapers in a desert.

‘Circumstantial evidence’

One of the key tools in World Weather Attribution’s more than 60 past reports has been creating computer simulations that compare an actual weather event to a fictional world without climate change, but in the Dubai case, there wasn’t enough data for those simulations to make such a calculation. But analysis of decades of past observations, the other main tool scientists use, showed the 10 percent to 40 percent bump in rainfall amounts.

Even without computer simulations, the clues kept pointing at climate change, scientists said.

“It’s not such a clear fingerprint, but we have lots of other circumstantial evidence, other lines of evidence that tell us that we see this increase,” said Imperial College of London climate scientist Friederike Otto, who coordinates the World Weather Attribution study team. “It’s what we expect from physics. It’s what we expect from other studies that have been done in the area, from other studies around the world, and there’s nothing else that’s going on that could explain this increase.”

There is a long-known effect in physics that finds the air holds 7 percent more moisture with every degree Celsius (4 percent for every degree Fahrenheit).

Otto said she has confidence in the conclusion but said this was one of the harder studies the team has undertaken.

El Nino, a natural occasional warming of the central Pacific that changes weather systems worldwide, was a big factor, the report said. These heavy Gulf downpours have happened in the past but only during an El Nino. And the researchers said those past deluges seem to be trending heavier — something scientists have long said would happen in many parts of the world as the world warms.