'Cloud seeding did not cause Dubai floods', expert says

Professor Maarten Ambaum, a meteorologist at the University of Reading who has studied rainfall patterns in the Gulf region, said: “This was an extremely heavy rainfall event which dumped a year’s worth of rain across a wide area in a single day. This part of the world is characterised by long periods without rain and then irregular, heavy rainfall, but even so, this was a very rare rainfall event.

“These storms appear to be the result of a mesoscale convective system – a series of medium-sized thunderstorms caused by massive thunderclouds, formed as heat draws moisture up into the atmosphere. These can create large amounts of rain, and when they occur over a wide area and one after another, can lead to seriously heavy downpours. They can rapidly lead to surface water floods, as we have seen in places such as Dubai airport.

“These types of intense rainfall events can be made more extreme due to climate change, as a warmer atmosphere will hold more water vapour. Climate scientists have been warning for many years that such extreme events will become more likely in a warmer climate and, indeed, we see this happening around us now.

“The UAE does have an operational cloud seeding programme to enhance the rainfall in this arid part of the world, however, there is no technology in existence that can create or even severely modify this kind of rainfall event. Furthermore, no cloud seeding operations have taken place in this area recently.

"Cloud seeding, as its name suggests, generally involves spreading fine particles into existing clouds into which conditions of wind, moisture and dust are insufficient to lead to rain. In this particular case, there would have been no benefit to seed these clouds as they were predicted to produce substantial rain anyway.

“It’s also worth noting that forecasters, including the Global Flood Awareness System (Glofas) which is run by the European Commission as part of the Copernicus programme, were very accurately forecasting a high risk of floods across a wide area of the region a full week ago. Forecasting systems such as this use detailed observations of conditions in the sea, air and land, and combine them in forecast models to predict future flood events. If these models were predicting that floods were highly likely a week ago, it’s unlikely that humans could do much about it, other than prepare themselves to get out of the way.”

Professor Giles Harrison, Professor of Atmospheric Physics at the University of Reading, said: "The UAE does do operational cloud seeding, but there is huge difference between what this can achieve – targeting individual, developing clouds with seeding material released from an aircraft – and the Dubai rainfall, which was associated with a large weather system advancing across the region. 

"There is such a fundamental mismatch of scale in the processes involved that I can’t see how the rainfall and cloud seeding could be related. And there would also be no reason to attempt cloud seeding in these circumstances, given the advance forecast of heavy rain.

"An increase in atmospheric moisture with a warmer climate has long been expected to lead to more extreme rainfall events."

Professor Suzanne Gray, Professor of Meteorology at the University of Reading, said: “Satellite imagery suggests the flooding and rainstorms Dubai were caused by something called a mesoscale convective system.

“Mesoscale convective systems (MCSs) are what we get when lots of individual thunderstorms amalgamate to form a single large high-level cloud shield, typically hundreds of kilometres across, together with a large region of heavy rainfall.

“They are not rare events for the Middle East. A recent published study analysed 95 events that occurred over the southern Arabian Peninsula from 2000-2020 and found that they most often occur in March and April. A previous event in March 2016 caused more than 240 mm of rain in Dubai in just a few hours, similar to the totals being reported for this event. This study also found that these MCSs have increased in longevity over the UAE over this 21-year period.

“MCSs do occur in the UK, but typically just a couple of times a year during the warmer months when they are usually associated with a plume of warm air coming from Spain.”

Professor Hannah Cloke, Professor of Hydrology at the University of Reading, said: "The pictures of the floods covering downtown Dubai are quite extraordinary. While massive floods like this have occurred in the past, the huge scale and intensity of the rainfall that caused it are exactly what we are seeing more of in our warmer world. If we don't rapidly curb warming by phasing out fossil fuels fast, we can expect to suffer more of these extreme floods in more parts of the world, more often.

"This is an extreme flash flood. Modern infrastructure in the developed Gulf states is built to withstand these types of events and drain standing surface water away. But with so much rain falling all at once, even carefully designed drainage systems will struggle to cope.

"Looking at the data from GloFAS, the Global Flood Awareness System, which is part of the Copernicus Emergency Management Service of the European Commission, there was very good early warning of widespread floods up to a week ago. This shows just how important it is for early warning systems to be in place in all parts of the world, and for governments, businesses and individuals to know what to do in response to early warnings. Natural hazards like floods only become disasters when people are in the wrong place and the wrong time. Any loss of life due to flooding is tragic, but is very often avoidable if working systems are put in place to keep people safe."