Could cloud seeding ease Arizona's drought? Lawmakers renew debate over 'geoengineering'

Yahoo

26-02-2025

As Arizona contends with one of the most severe long-term droughts on record, scientists and water managers have considered weather manipulation techniques to increase the state's sporadic precipitation.
But Republican lawmakers have advanced a bill in the Legislature, Senate Bill 1432, that would ban geoengineering projects in Arizona, casting doubt on the efficacy and safety of such methods.
If passed, the bill would prohibit geoengineering in Arizona that disseminates chemicals or substances into the air that could manipulate sunlight intensity, reflecting solar radiation back to space.
The bill was revised to exclude weather manipulation and cloud seeding, a technique Salt River Project has researched that could increase precipitation and safeguard Arizona's water supply.
SB1432 passed the Senate Natural Resources Committee and was sent to the full Senate for a vote. A similar bill in the House, HB2056, has not advanced.
Geoengineering and weather manipulation have become entangled with conspiracy theories and controversy, and scientists and lawmakers across the country are wading into new territory as they explore solutions to drought and climate change.
But what is geoengineering, and is weather manipulation possible or even effective in Arizona, one of the driest states in the country?
'Geoengineering is being conflated with smaller-scale efforts like weather modification,' said Eric Betterton, a professor emeritus in hydrology and atmospheric sciences at the University of Arizona. 'Theoretically, it could work here, but it's yet to be proven.'
As climate change worsens due to the effects of greenhouse gas emissions in the atmosphere, scientists have explored geoengineering as a potential solution, or at least a way to mask the symptoms of a warming climate.
Geoengineering is often associated with weather manipulation, but the two fields largely differ.
Geoengineering is a blanket term to describe large-scale interventions in environmental processes to offset climate change. It focuses on the atmosphere's composition, while weather manipulation aims to influence existing weather conditions.
According to Betterton, there are two primary geoengineering tactics: carbon removal and solar geoengineering.
Carbon geoengineering removes carbon dioxide from the atmosphere and injects it underground to reduce global warming.
Solar geoengineering injects sulfate aerosols into the stratosphere and reflects sunlight, limiting the amount of heat trapped in the atmosphere.
Carbon removal has been conducted on a large scale in the U.S. and Europe, and solar reflection has been investigated on smaller scales due to the controversial nature of injecting chemicals into the atmosphere.
'The idea is one injects sulfur dioxide into the upper atmosphere, and it is converted to sulfate aerosols,' Betterton said. 'They become like a white haze and reflect some of the sunlight coming in and thereby cooling Earth.'
But solar reflection can occur naturally. Scientists have observed an influx of sulfur dioxide and aerosols into the stratosphere after major volcanic eruptions. These eruptions can cool the planet, with effects lasting several years.
Betterton acknowledges the long-term effects and unintended consequences of solar geoengineering are unknown and should be pursued carefully following peer-reviewed, scientific studies.
While SB1432 is the latest example of lawmakers and public wariness towards geoengineering, there's serious disagreement around it even in the scientific community.
'There is a lot of controversy,' Betterton said. 'Some scientists believe by even considering geoengineering, you reduce the importance of minimizing greenhouse gas emissions. In other words, you're giving up.'
Other scientists believe it's important to discover the implications of geoengineering by doing small-scale experiments in case carbon reduction efforts fail.
While scientists can't summon thunderstorms to Arizona or direct snowstorms to the Northeast, tactics are being explored to alter existing weather conditions.
But they can't create something from nothing — there has to be enough moisture and clouds in the atmosphere to attempt weather manipulation.
Cloud seeding and hail suppression stem from cloud modification, but their efficacy is still uncertain. 'For cloud seeding, first you need clouds,' Betterton said. 'If you don't have clouds, you have nothing to work on.'
Scientists release silver iodide from airplanes in most cloud-seeding operations, spurring ice formation and allowing precipitation to occur sooner.
Betterton conducted a cloud seeding program in the 1990s near Sedona. His team took advantage of the Mogollon Rim, where winter westward winds generate clouds as they rise over the topography.
Like the rest of the scientific community, they weren't confident cloud seeding was all that effective.
'The problem is, when you modify the clouds, does that result in precipitation at the surface? We could not show that, and no one has really been able to show that,' Betterton said.
Some believe cloud seeding could create a long-term 5% to 10% increase in precipitation, but there is not enough data to say so confidently.
Hail suppression is another weather manipulation technique being explored. Scientists intentionally overseed a cloud in an attempt to prevent the formation of hail. It isn't as prevalent in Arizona, but agricultural areas have explored the technique to minimize hail damage.
The Southwest has been in a drought since 1994, one of the worst on record. But even outside of long-term drought, Arizona is dry.
The statewide average is about 12 inches of rain annually since measurements began in 1816 and about 11 inches during the current drought. Some places get even less rain, with Phoenix accumulating an average of 7.22 inches.
Geoengineering and cloud seeding could theoretically offset the effects of drought and climate change in Arizona.
Betterton believes that even if cloud seeding has minimal impacts on overall precipitation, it is still a worthwhile endeavor if scientists can prove it works and is conducted safely.
'Any way you can increase precipitation would improve Arizona's amount of water,' he said.
Theoretically, cloud seeding is possible in Arizona during the winter, because scientists can rely on cloud formation over the Mogollon Rim.
'The problem during the summer is we do get those big convective clouds, but you never know where they're going to pop up,' Betterton said. 'So how do you get the cloud seeding material to the cloud that you don't even know is going to be there until it actually occurs?'
But there is no active cloud seeding in Arizona. It is becoming more prevalent across the West, and nine U.S. states actively cloud seed: California, Colorado, Idaho, Nevada, New Mexico, North Dakota, Texas, Utah and Wyoming.
SRP has conducted research exploring the feasibility of cloud seeding over the White Mountains, but it was limited to computer models and no cloud seeding occurred.
'SRP is not participating in any cloud seeding flights at this time, and there are no plans in the near future,' said SRP spokesperson Patty Garcia-Likens.
Meanwhile, several states have introduced legislation to ban geoengineering.
Even if the geoengineering ban passes, it doesn't mean the area won't be affected by such activities occurring elsewhere.
'There's no way they can legislate against geoengineering,' Betterton said. 'Because it could take place in California, over the Pacific or in Asia if someone flies an airplane up into the stratosphere and releases sulfur dioxide, it's going to circulate around Earth.'
Arizona legislators question the safety of injecting chemicals into the atmosphere or clouds to alter the weather or climate change, but some environmentalists see it as a distraction from bigger issues.
'To me, it's just so infuriating that they're focusing on this but they won't address climate change, which is modifying weather,' said Sandy Bahr, the director of the Sierra Club's Grand Canyon Chapter.
Hayleigh Evans writes about extreme weather and related topics for The Arizona Republic and azcentral.com. Email her with story tips at [e-mail].
This article originally appeared on Arizona Republic: Geoengineering, weather modification spurs Arizona Legislature debate