Scenes of flood-ravaged neighborhoods in one of the planet’s driest regions stunned the world this month. Heavy rains in the United Arab Emirates and Oman submerged cars, clogged highways and killed at least 21 people. Flights out of Dubai’s airport, a major global hub, were severely disrupted.
The downpours weren’t a total surprise — forecasters had anticipated the storms several days earlier and issued warnings. But they were certainly unusual.
Here’s what to know.
Heavy rain there is rare, but not unheard-of.
On average, the Arabian Peninsula receives a scant few inches of rain a year, although scientists have found that a sizable chunk of that precipitation falls in infrequent but severe bursts, not as periodic showers. These rains often come during El Niño conditions like the ones the world is experiencing now.
U.A.E. officials said the 24-hour rain total on April 16 was the country’s largest since records there began in 1949. And parts of the nation had already experienced an earlier round of thunderstorms in March.
Oman, with its coastline on the Arabian Sea, is also vulnerable to tropical cyclones. Past storms there have brought torrential rain, powerful winds and mudslides, causing extensive damage.
Global warming is projected to intensify downpours.
Stronger storms are a key consequence of human-caused global warming. As the atmosphere gets hotter, it can hold more moisture, which can eventually make its way down to the earth as rain or snow.
But that doesn’t mean rainfall patterns are changing in precisely the same way across every part of the globe.
In their latest assessment of climate research, scientists convened by the United Nations found there wasn’t enough data to have firm conclusions about rainfall trends in the Arabian Peninsula and how climate change was affecting them. The researchers said, however, that if global warming were to be allowed to continue worsening in the coming decades, extreme downpours in the region would quite likely become more intense and more frequent.
Hot oceans are a big factor.
An international team of scientists has made a first attempt at estimating the extent to which climate change may have contributed to April’s storms. The researchers didn’t manage to pin down the connection precisely, though in their analysis, they did highlight one known driver of heavy rain in the region: above-normal ocean temperatures.
Large parts of the Indian, Pacific and Atlantic Oceans have been hotter than usual recently, in part because of El Niño and other natural weather cycles, and in part because of human-induced warming.
When looking only at El Niño years, the scientists estimated that storm events as infrequent as this month’s delivered 10 percent to 40 percent more rain to the region than they would in a world that hadn’t been warmed by human activities. They cautioned, however, that these estimates were highly uncertain.
“Rainfall, in general, is getting more extreme,” said Mansour Almazroui, a climate scientist at King Abdulaziz University in Jeddah, Saudi Arabia, and one of the researchers who contributed to the analysis.
The analysis was conducted by scientists affiliated with World Weather Attribution, a research collaboration that studies extreme weather events shortly after they occur. Their findings about this month’s rains haven’t yet been peer reviewed, but are based on standardized methods.
The role of cloud seeding isn’t clear.
The U.A.E. has for decades worked to increase rainfall and boost water supplies by seeding clouds. Essentially, this involves shooting particles into clouds to encourage the moisture to gather into larger, heavier droplets, ones that are more likely to fall as rain or snow.
Cloud seeding and other rain-enhancement methods have been tried around the world, including in Australia, China, India, Israel, South Africa and the United States. Studies have found that these operations can, at best, affect precipitation modestly — enough to turn a downpour into a bigger downpour, but probably not a drizzle into a deluge.
Still, experts said pinning down how much seeding might have contributed to this month’s storms would require detailed study.
“In general, it is quite a challenge to assess the impact of seeding,” said Luca Delle Monache, a climate scientist at the Scripps Institution of Oceanography in La Jolla, Calif. Dr. Delle Monache has been leading efforts to use artificial intelligence to improve the U.A.E.’s rain-enhancement program.
An official with the U.A.E.’s National Center of Meteorology, Omar Al Yazeedi, told news outlets that the agency didn’t conduct any seeding during the latest storms. His statements didn’t make clear, however, whether that was also true in the hours or days before.
Mr. Al Yazeedi didn’t respond to emailed questions from The New York Times, and Adel Kamal, a spokesman for the center, didn’t have further comment.
Cities in dry places just aren’t designed for floods.
Wherever it happens, flooding isn’t just a matter of how much rain comes down. It’s also about what happens to all that water once it’s on the ground — most critically, in the places people live.
Cities in arid regions often aren’t designed to drain very effectively. In these areas, paved surfaces block rain from seeping into the earth below, forcing it into drainage systems that can easily become overwhelmed.
One recent study of Sharjah, the capital of the third-largest emirate in the U.A.E., found that the city’s rapid growth over the past half-century had made it vulnerable to flooding at far lower levels of rain than before.
Omnia Al Desoukie contributed reporting.