Iran has begun a cloud-seeding operation to induce rainfall amid its worst drought in decades, which threatens to force the evacuation of Tehran. The effort started on 15 November and will continue until May, but experts warn it offers only modest benefits. While recent rains have brought some relief, the underlying water crisis persists due to climate factors and mismanagement.
Iran is grappling with an unprecedented drought that has drastically reduced water supplies across the country. Rainfall is 85 per cent below average, with Tehran receiving just 1 millimetre of rain this year. Officials report that reservoirs in the capital and nearby regions are in a "worrying state," with water capacity under 5 per cent at 32 dams, and satellite images show some have dried up entirely.
Tehran residents have cut water consumption by about 10 per cent, but authorities say this is insufficient. Measures include reducing water pressure at night and planning fines for excessive use. Iran's president has warned that if rainfall does not improve by December, the city's 14 million residents may need to evacuate.
The drought, lasting five years, stems partly from the climate crisis, marking Iran's driest autumn in 50 years. Tehran, typically seeing snow in November, has experienced temperatures of 15°C (59°F) or higher. However, Kaveh Madani, a former Department of Environment official, attributes the crisis mainly to poor management, including expanded agriculture in dry areas and half a million illegal wells depleting groundwater, leading to what he calls Iran's "water bankruptcy."
To combat this, Iran initiated cloud seeding on 15 November, dispersing agents from cargo planes, drones, and ground generators around Lake Urmia, which has largely dried up over two decades. The operation aims to last through the rainy season until May. Early results showed up to 2.7 centimetres of rain in areas west of the lake the next morning, per a University of California, Irvine precipitation map.
Cloud seeding, developed in the 1940s by scientists like Bernard Vonnegut, involves spreading particles such as silver iodide to encourage water droplets in clouds to form ice crystals and fall as precipitation. Yet, its effectiveness is hard to quantify due to natural cloud variability, as noted by Andrea Flossmann at University Clermont Auvergne: "The effects are very difficult to show because of the large natural variability of clouds."
A 2014 experiment in Wyoming suggested it could boost precipitation by 5 to 15 per cent. In Iran's arid conditions, however, suitable clouds with ample moisture are scarce. Karen Howard, a US Government Accountability Office scientist, explains: "Cloud seeding is often much more difficult during a drought because the atmosphere is so dry, and any clouds that are present may not have sufficient moisture."
Recent weather systems from the Black Sea brought rains and flooding to western provinces like Ilam and Kurdistan on 16 November, offering a chance for seeding to enhance yields. Armin Sorooshian at the University of Arizona says it can "squeeze out a few more drops" from such systems, but "it's not going to lead to extreme things like flooding or solving widespread drought." Experts emphasize that while helpful, cloud seeding alone cannot resolve Iran's water crisis.