The insemination of clouds

Man-made flood in Dubai? How cloud seeding works

The National Meteorological Centre in Dubai said it had 'seeded' clouds from 14-15 April

17 April 2024

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3' min read

Over 140 millimetres of rain fell in 24 hours in an area that on average receives 95 millimetres in a year. The violent cloudburst that hit Dubai on 16 April left meteorologists stunned. Roads flooded, cars swept away, one of the world's busiest airports forced to close for half an hour, residents stranded in their homes and offices. In Al-Ain, 100 kilometres north of Dubai, as much as 256 millimetres of water fell in 24 hours.

It was indeed an extreme phenomenon and experts are questioning the causes. The debate is focusing on an activity that the United Arab Emirates (and others) have been using for some time: 'cloud seeding', literally 'cloud seeding'.

What is cloud seeding

Seeding is done using aircraft that inject salt or silver iodide particles into the clouds to form ice crystals that condense into rain or snow, depending on the altitude. According to the World Meteorological Organisation, under optimal conditions, seeding can increase the precipitation of a single cloud by up to 20 per cent.

Are the heavy rains in Dubai due to cloud seeding?

The United Arab Emirates has been using seeding since at least 2002 to deal with drought problems. The emirate's National Meteorological Centre, according to Bloomberg Agency, said it sowed clouds on 14 and 15 April, but not on 16 April, the day of the flood. The meteorological centre did not confirm the information to other media. If this technique was used on the eve of the cloudburst, it is less clear to what extent it contributed to the unprecedented amount of rain that fell on the Gulf's financial and commercial hub. According to experts questioned by the BBC, if cloud seeding did play a role, it was a marginal contribution and it is therefore wrong to place the main responsibility on it.

Il maltempo blocca l'aereoporto di Dubai

How effective is cloud seeding?

Cloud seeding does not work from scratch: chemicals must be injected into existing clouds. It has proven effective when targeting rain clouds in mountainous areas - in other words, when it aims to increase rainfall. By contrast, there is conflicting scientific evidence regarding its effectiveness on clouds that may not bring rain, in flat regions and during droughts.

Long-term planting projects have increased the snowpack in limited areas of the US mountains of Nevada by about 10% per year, according to research by the non-profit Desert Research Institute. Similar results have been recorded in Wyoming's Snowy Range and Sierra Madre Range, as well as in Australia's Snowy Mountains.

What is the story of cloud seeding?

Cloud seeding was developed in the 1940s and became popular in the US in the 1950s and 1960s, when farmers, hydroelectric companies and ski resorts benefited from additional rainfall. In the following decades, however, it fell into disuse as government funding dried up following revelations that the US had implemented a secret military seeding programme during the Vietnam War. In 1977, the United States, Russia, India and some European nations signed the Convention on Environmental Modification, which banned weather modification techniques for military purposes.

Other countries are exploring it as accelerating climate change exacerbates droughts and the struggle for water. It is used in the western states of the USA and in European countries, including France and Spain. China regularly uses it for irrigation and to regulate rainfall in Beijing, including during the 2008 Olympics.

EPA/STRINGER

Is cloud seeding dangerous?

The increasing use of this technology led to the formation of a working group on weather modification within the World Meteorological Organisation (WMO), which warned in a 2023 report about the lack of knowledge of the impacts of this technology.

Other concerns include the alteration of existing local weather patterns, which can lead to undesirable conditions such as hail in agricultural areas. Omm experts also warn that chemicals such as silver iodide are toxic and their use should be monitored for potential harmful effects on health and the environment.

What role has climate change played?

Individual weather events are not directly influenced by climate change, which has a long-term time span. However, record rainfall is one of the phenomena consistent with the way the climate is changing.

In fact, warmer air can retain more moisture - about 7% more per degree - which in turn can increase the intensity of rainfall.

"The intensity of rainfall in Dubai has been record-breaking," Richard Allan, professor of climate science at the University of Reading, told the BBC, "but it is consistent with a warming climate, with increased moisture availability fuelling storms and making rainfall events and related flooding more powerful.