US cloud-seeding efforts 'limited by fragmented approach and lack of data'

UAE and Saudi Arabia's rain enhancement research programmes cited by Government Accountability Office

The US Government Accountability Office mentioned the UAE and Saudi Arabia's cloud-seeding programmes. Photo: UAE National Centre of Meteorology

Unlike in the UAE, Saudi Arabia and China, cloud-seeding efforts to boost rainfall in the US remain minimal, according to a new report from the Government Accountability Office.

Cloud seeding often involves shooting salt or other small materials into clouds to try to generate extra rain. The new report, issued to the US House Committee on science, space and technology, said the process could help mitigate drought challenges from climate change. However, it warned that the country's fragmented approach, combined with inconclusive international data leave ample room for improvement before cloud-seeding is hailed as a silver bullet solution.

According to the Government Accountability Office research, cloud seeding is mostly funded at a local level, with nine US states – California, Colorado, Idaho, Nevada, New Mexico, North Dakota, Texas, Utah and Wyoming – having active programmes.

However, the research also pointed out that Tennessee passed a law in 2024 prohibiting cloud seeding, and nine other states had similar bills being considered.

“Federal agencies have provided little direct support for cloud-seeding activities or research since the early 2000s,” the GAO said. According to the World Meteorological Organisation, at least 50 counties had active weather modification programmes with various cloud-seeding efforts, it added.

Yet despite the ambitious global efforts to increase water supplies and bolster agriculture, the GAO warned that it was difficult to estimate cloud-seeding effectiveness.

“In some studies we reviewed … the estimated effect was not distinguishable from zero with a high degree of statistical confidence,” the GAO said. It also pointed out that it is one thing to increase rainfall, but it is another to do something productive with that rain.

Map of states with active cloud seeding programmes in 2024. Source: US government accountability office report

“Additional uncertainty exists regarding the extent to which cloud seeding can ultimately improve usable water supplies. Even if baseline and additional precipitation are accurately estimated, the amount of precipitation that is lost to evapotranspiration is uncertain because of variations in climate, land surface, and vegetation coverage,” the report continued. Evapotranspiration is the process by which water moves from the land to the atmosphere, through evaporation from the soil and transpiration through plant leaves and stems.

A key challenge facing a more comprehensive US cloud-seeding plan, the GAO explained, was the limited window in which seeding operations could be successfully conducted. “Operations can only enhance precipitation when the right kind of clouds are present, which limits opportunities for success … The natural variability of cloud processes adds further uncertainty to the task of selecting clouds to target.”

The report said the US would need to allocate more resources to get a better idea about cloud seeding's potential effectiveness. It also noted that India in recent years had begun to experiment with the process in the hope that increased rain could help to reduce air pollution. China probably has one of the most comprehensive weather modification programmes, which includes cloud-seeding research.

The GAO also mentioned the UAE and Saudi Arabia for having prominent cloud-seeding programmes. In 2023, the UAE’s Ministry of Climate Change and Environment told The National that the country’s rain enhancement programme had conducted 311 cloud-seeding missions in the previous year, clocking up close to 1,000 flying hours. That marked a significant increase on the 177 flights conducted in 2016.

The UAE has also been prolific in providing grants for rain enhancement projects. Experts from the National Centre of Meteorology have said seeding could enhance rainfall by about 30 per cent in a clean atmosphere or by 15 per cent in a dusty atmosphere, but acknowledged the complexities and the need for more research.

The science behind rain enhancement and cloud seeding has piqued plenty of interest, though some accounts have proved fanciful. In October, meteorology experts debunked a theory circulating among some US conservatives that Hurricane Milton in Florida had been created by the government. Even US President Joe Biden came forward to call the claim “beyond ridiculous.”