Disturbance to Earth’s climate system is more likely and less predictable than ever before.
Citizens in the United Arab Emirates and Oman are still trying to return to normal life after record-breaking rainfall this week. The storm forced the closure of schools, offices and businesses, turned the tarmac at Dubai International Airport into a rough sea, and killed more than 20 people in both countries. The downpour looked almost apocalyptic: On Tuesday, the UAE received as much rain as it usually gets all year.
Early reports of the weather event sparked some speculation that controversial weather-modifying technology was causing the conditions to worsen. The practice, known as “cloud seeding,” involves spraying chemicals into the air in an effort to squeeze more rain from the sky. Hundreds of such operations are carried out each year in the United Arab Emirates to replenish water resources in arid areas. Scientists have long debated just how effective cloud seeding is, but the technology can’t create rain clouds out of thin air; it can only enhance existing clouds.
The current consensus seems to be that artificial rainfall is unlikely to have a significant impact on this week’s historic flooding. (The UAE’s weather agency said no seeding missions were underway before the storm.) But the incident once again raised some basic questions about disturbing nature. Artificial seeding is a type of geoengineering, a set of technologies designed to influence or change the Earth’s climate system. The warmer our planet becomes, the more attractive geoengineering seems as a way to slow down or endure the effects of climate change, and the less accurate our predictions of its effects become. Scientists can’t be sure that God playing with the atmosphere wouldn’t cause pain to humans, even if it was intended to alleviate suffering.
When it comes to cloud seeding, humans have been playing God for decades. The technology dates back to the 1940s and has been regularly deployed around the world ever since, providing relief in drought-stricken areas, clearing skies ahead of the Olympics and adding an inch of snow to ski resorts. Scientists have long been studying artificial rainfall, but they have only recently managed to document how the technology actually works, distinguishing between natural precipitation and that caused by human intervention. Janette Lindesay, a climate scientist at the Australian National University, told me that experts believe seeding could squeeze out a small amount of additional precipitation, but it’s notoriously difficult to determine how effective it will be in any given situation.
The basic principle of cloud seeding is simple, Lindsay said: If you want it to rain, you release chemicals that encourage clouds to create larger water droplets that are more likely to reach the ground. If you want to suppress rainfall, you can use chemicals to encourage the production of smaller water droplets. But this simplicity masks the complex science and high stakes of manipulating the atmosphere in the 21st century. The 2020s will be characterized by a warming climate capable of holding more moisture, conditions that could lead to more extreme and unprecedented weather events, including heavy rainfall. Add geoengineering to the mix and things can get dangerous. “We’re in a situation now where we’re not necessarily relying on past experience and past results to tell us what’s likely to happen when we step in,” Lindsay said.
As geoengineering goes, cloud seeding is a fairly limited technology, with impacts limited to small geographic areas. (This is part of the reason why opposition to seeding emerged as a significant contributing factor to this week’s flooding in the Middle East; as Amit Katwala writes in wired This week, heavy rains also hit parts of the UAE that don’t normally sow. Scientists are still debating whether artificial rainfall in one area has an impact on another. At a time when droughts are becoming more common, rainwater is a valuable commodity with geopolitical importance. In recent years, Iran has accused the United Arab Emirates and Israel of stealing rainwater, and both countries have had their own sowing experiments.
Laura Kuhl, a public policy professor at Northeastern University who studies climate adaptation, said reports that cloud seeding contributed to this week’s flooding may be false, but the responses they triggered are representative of what happens when we interfere with natural systems. A healthy skepticism. This is especially true, she says, when you consider forms of geoengineering that are premised on producing large-scale effects. Scientists have proposed injecting sulfur dioxide into the stratosphere to reflect some of the sunlight back into space, preventing it from reaching the Earth’s surface. The resulting aerosols may remain in the stratosphere for years, changing with winds. Similar concerns surround another geoengineering technique that involves spraying salt compounds into the air to brighten clouds, thereby reflecting sunlight back into space. This month, scientists secretly tested the technology, the first of its kind in the United States. Juan Moreno-Cruz, a climate policy researcher at the University of Waterloo, told me that the field is moving much faster than before.
With further research, some geoengineering techniques may well become useful methods of mitigating or adapting to climate change. But they fail to address the root cause: the burning of fossil fuels and the failure to reduce greenhouse gas emissions. Many climate experts see geoengineering as a last resort. As our changing atmosphere continues to drendle some parts of the planet and make others chronically dry, a last resort may start to look like a more attractive option, even as the consequences of getting it wrong become increasingly clear. The more terrifying it is.
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