Circumstantial evidence points to climate change worsening the deadly deluge that inundated Dubai and other parts of the Persian Gulf, but scientists have failed to discover the definitive fingerprints of greenhouse gas-induced warming they have seen in other extreme weather events, according to a new report. to create.
Between 10 percent and 40 percent more It only rained on one day last week The 1.2 degrees Celsius from burning coal, oil and natural gas since the mid-19th century is much higher than it would have been in a world without it, scientists at World Weather Attribution said Thursday in a breaking study that is too new to be peer-reviewed.
At at least one point, a record 28.6 centimeters of rain fell in just 24 hours; This was more than twice the annual average and paralyzed the usually bustling city full of desert skyscrapers.
Heavy rains and flooding have killed at least two dozen people in parts of the United Arab Emirates, Oman and Saudi Arabia.
How does climate change affect precipitation?
A key tool in WWA’s more than 60 past reports was to create computer simulations that compared a real weather event to a fictional world without climate change.
In the Dubai case, there was not enough data for the simulations to make such a calculation. But the other key tool they used, analysis of decades of historical observations, showed a 10 percent to 40 percent increase in rainfall amounts.
Clues were hidden even without computer simulations points to climate changesaid the scientists.
“It’s not a very clear fingerprint, but we have a lot of circumstantial and other evidence to say we’re seeing this increase,” said Imperial College of London climate scientist Friederike Otto, who coordinated the attribution study team.
“This is what we expect from physics. “This is what we expect from other studies in this area and other studies around the world, and there is nothing else that can explain this increase.”
There is an effect that has been known for a long time in physics; It reveals that the air retains 7 percent more moisture with every degree Celsius.
Otto said he was confident in the outcome, but said it was one of the most difficult attribution studies the team had undertaken.
If there was no El Niño, there would be no floods
El NiñoNatural sporadic warming in the Central Pacific that changes weather systems around the world is a big factor, the report said.
These heavy downpours in the Gulf have happened in the past, but only during El Niño. Researchers said past flooding has become worse; Scientists have long said that this would happen in many parts of the world as the world warms.
This flood came from two different places and almost simultaneously. storm systemsThis wouldn’t have happened if El Niño hadn’t happened, said study co-author Mansour Almazroui, from the Center of Excellence for Climate Change Research (CECCR) at King Abdulaziz University in Saudi Arabia. Otto added that this would not be the case if there were no human-caused climate change.
Because rainfall amounts vary by region and due to a lack of data, the report was unable to put a figure on whether climate change is increasing the likelihood of such showers in Dubai; but Otto estimated that the chances of this happening are currently about three times higher. compared to pre-industrial times.
Does cloud seeding play a role in heavy rain in Dubai?
The report and its authors poured cold water on speculation that the UAE’s cloud seeding had anything to do with the amount or chance of rain.
Many scientists dispute the effectiveness of cloud seeding in general. Even if, clouds in the storm system are not planted, the report said. Otto said the results (if any) of cloud seeding are generally faster. And this storm was predicted days in advance.
“Such precipitation never comes from cloud seeding,” Almazroui said at Thursday’s press conference.
Andrew Weaver, a climate scientist at the University of Victoria in Canada, said that although the authors used well-established techniques and that is what scientists expect about climate change, conclusions should not be drawn when there is a disagreement between computer simulations and observations. part of the research.
This is strong enough greenhouse gas emissions Several outside scientists have said this is a factor.
Malte Meinshausen, a climate scientist at Australia’s University of Melbourne, called Thursday’s study “a well-balanced, impressively detailed and sufficiently conservative assessment.”
“This study, combined with theory and attribution studies associated with other increasingly frequent extreme rain and flood events around the world, provides compelling evidence that climate warming is supercharging the recent extreme rainfall and flood event in the UAE and Oman,” said climate scientist Jonathan. said. Overpeck, Dean of the School of Environment at the University of Michigan.
“This is what global warming is becoming more and more like; more severe climate extremes and human suffering.”