AN IMPERFECT STORM

CAN THE U.A.E. REALLY MAKE RAIN ON DEMAND OR IS IT SELLING VAPORWARE?

- AMIT KATWALA

1 IN THE SKIES OVER AL AIN, IN THE United Arab Emirates, pilot Mark Newman waits for the signal. When it comes, he flicks a few silver switches on a panel by his leg, twists two black dials, then punches a red button labeled FIRE.

A slender canister mounted on the wing of his small propeller plane pops open, releasing a plume of fine white dust. That dust-actually ordinary table salt coated in a nanoscale layer of titanium oxide-will be carried aloft on updrafts of warm air, bearing it into the heart of the fluffy convective clouds that form in this part of the UAE, where the many-shaded sands of Abu Dhabi meet the mountains on the border with Oman. It will, in theory at least, attract water molecules, forming small droplets that will collide and coalesce with other droplets until they grow big enough for gravity to pull them out of the sky as rain.

This is cloud seeding. It's one of hundreds of missions that Newman and his fellow pilots will fly this year as part of the UAE's ambitious, decadelong attempt to increase rainfall in its desert lands.

Sitting next to him in the copilot's seat, I can see red earth stretching to the horizon. The only water in sight is the swimming pool of a luxury hotel, perched on the side of a mountain below a sheikh's palace, shimmering like a jewel.

More than 50 countries have dabbled in cloud seeding since the 1940s-to slake droughts, refill hydroelectric reservoirs, keep ski slopes snowy, or even use as a weapon of war. In recent years there's been a new surge of interest, partly due to scientific breakthroughs, but also because arid countries are facing down the early impacts of climate change. Like other technologies designed to treat the symptoms of a warming planet (say, pumping sulfur dioxide into the atmosphere to reflect sunlight into space), seeding was once controversial but now looks attractive, perhaps even imperative.