Terry Farver was tired of the rain.
In other years at other times of the year, the Scobey farmer would have celebrated the moisture. But 8.5 inches of rain was not supposed to descend upon northeastern Montana during the fall harvest.
The result: He and his neighbors couldn’t get their crops in, or if they could, the water had diminished the quality of grain so it was harder to sell. Either way, they were in tough straits.
Two years ago, those farmers had the opposite dilemma as Montana suffered through the most intense period of drought in at least 20 years.
“The hardest part about this year is that we just came off two years of drought, so when it started to rain and the crops were so good, we all thought this crop might heal up some of the economic challenges we’ve been facing from the past two years of drought,” Farver said in a letter to the American Farm Bureau.
With agriculture being Montana’s No. 1 industry, state politicians are trying to find solutions. That’s why the Legislature is studying whether the state should invest in cloud seeding or at least make it easier for groups to conduct their own.
According the North American Weather Modification Council, Montana is one of five Western states that doesn’t seed clouds. Six other states do, including Idaho and Wyoming.
In September, the Water Policy interim committee heard from two Idaho residents who touted the possible benefits of cloud seeding, including Jim Haganbarth, who also ranches in southwestern Montana.
“We need all the water we can get. It’s going over our heads,” Haganbarth told the committee. “What we have to do is understand it’s not a threat to this state.”
It’s easy to see why people, especially farmers and ranchers, would like to control the rain. And it’s not surprising that in the past, those claiming to make rain or divine water could cheat communities out of their money, especially after the Dust Bowl of the 1930s.
Around the same time, about a century ago, a few rainmakers appeared who used more than mystical shenanigans to coax water from the sky.
In 1915, the city of San Diego hired Charles Hatfield to break a devastating drought, and it appeared that he did, releasing “a secret 23-chemical cocktail into the air from tall wooden towers perched on stilts.”
Hatfield was using an early precursor to today’s cloud seeding. He was sending chemical and smoke particles into the clouds coming off the ocean. If moisture was present, it could cluster around the particles until it became heavy enough to fall to the ground.
But the question remained: Was his technique responsible for the 30 inches that fell the following month or were natural weather patterns such as El Nino responsible?
For the most part, that question still haunts the process of cloud seeding.
“Cloud seeding has been controversial because scientists couldn’t really show cloud seeding works,” said atmospheric scientist Katja Friedrich of the University of Colorado. “The reason is you have these big Pacific storms coming in, they already produce a lot of precipitation, and you’re seeding on top of it. It’s difficult to distinguish between what is natural precipitation and seeded precipitation.”
Today, most cloud seeding in the West is conducted over high mountains during the winter, because the best place for the precipitation to go is the snowpack. Big winter storms provide the most bang for the buck.
If summer storms are seeded, any added rain is quickly lost to the ground so the benefit is brief. Also some weather systems don’t have enough moisture to make cloud seeding worthwhile. So ranchers like Haganworth will still have to watch water pass overhead.
“In the end, it’s a cost-benefit analysis – if the price of water goes up, it’s probably worth doing. If the price goes down, then it’s probably not worth doing,” Friedrich said. “I think that’s why some of the states were more hesitant than others.”
During cloud seeding, a plane drops silver iodide for an hour into a strong weather system passing over the mountains. The particles can remain in the air for about an hour. So about two hours of added precipitation may fall during a long-duration blizzard.
Idaho Power scientist Derek Blestrud told the Water Policy committee that he’d estimated precipitation increases of between 5% and 15% in various Idaho basins.
Friedrich knows cloud seeding works under certain conditions. She conducted an experiment where she seeded clouds that weren’t snowing and got snow while the surrounding clouds produced nothing.
“We could quantify how much water was produced from these clouds that did not precipitate. But again, it wasn’t very much,” Friedrich said.
But when seeding clouds that are already producing snow, Friedrich said, it’s difficult to know how much seeding actually contributes to the overall precipitation.
“Quantifying is the big question,” Friedrich said. “In the literature, you see numbers from 0% to 50%. I always say you can pick a number because we don’t know.”
That’s the also reason it’s hard to know whether cloud seeding can affect the amount of moisture that drops on regions downwind. With limited cloud seeding operations, any effect is probably not noticeable, Freidrich said. So it’s not like Colorado is taking water that might have dropped on Nebraska. But if cloud seeding expands greatly, such effects may need to be researched.
States like California want Colorado to take as much water as it can in hopes that more water will flow down the Colorado River. A few multi-state initiatives have formed to encourage headwater states to use cloud seeding for that reason.
But cloud seeding is no antidote to drought brought on by climate change that can hit entire states hard. As climate change shifts the winds aloft, dry air masses can sit above regions for weeks so there are no moisture-laden clouds to seed.
Climate change is also making winter weather unpredictable. So if cloud seeding is used to add to the December snowpack, it could be lost to a dry or warm January. Climate change is also shifting snowmelt into March. So early runoff could defeat the point of cloud seeding unless water managers can figure out how to preserve the water until the growing season.
Friedrich said cloud seeding could provide a small benefit under certain conditions, but it should be just one tool.
“We need to look at the entire picture – how can we conserve water? Or what’s our water budget downstream?” Friedrich said. “Can we shut down (systems) that need too much water? Add cloud seeding? It’s probably not one or the other. But cloud seeding is maybe just a piece of it.”
Contact Laura Lundquist at firstname.lastname@example.org.