After last year’s record wildfire season, Canada is bracing for more heat this summer and the looming risk of “damaging” forest fires.
Rain could prove critical for firefighting efforts this month, according to government officials. But what about artificial rain?
Cloud seeding, which can cause precipitation by human intervention, is an old method but one that continues to be developed and explored.
Some experts say it has the potential to mitigate wildfires, but more research is needed to evaluate how viable and effective it can be in the future.
“Cloud seeding was a very interesting topic back in the ’60s and ’70s and then it sort of died out,” said Zamin Kanji, an expert in atmospheric physics at ETH Zurich in Switzerland.
“And now it’s becoming important again in terms of climate, water resource research and precipitation enhancement,” he told Global News in an interview.
“So I think there could be potential there, a lot of potential.”
What is cloud seeding?
Cloud seeding, which was invented in the 1940s, has been used around the world to artificially modify weather.
Dozens of countries have deployed the method to create — and even prevent — rain and snowfall and manage the Earth’s temperature.
In Canada, cloud seeding has only been used in Alberta to suppress hailstorms.
Kanji, said there are basically two pathways to cloud seeding: warm cloud seeding and cold cloud seeding.
In warm cloud seeding, the idea is to inject aerosol particles, typically below one micrometre in diameter, into the atmosphere to create cloud droplets that eventually grow big enough to effectively collide with other droplets and become precipitation-sized droplets that fall down as rain.
As for cold cloud seeding, aerosol particles that are effective at forming ice crystals are injected into clouds that are below zero degrees — called “supercooled clouds.”
“If you inject these particles into the supercooled cloud, you artificially enhance ice formation and then create these ice crystals that are large enough to settle out of the cloud and melt and fall down as raindrops,” Kanji explained.
Substances like silver iodide, table salt or potassium chloride can be used in these processes, said Roelof Burger, an environmental sciences and management professor at North-West University in South Africa.
Humans can spray the substance from planes or drones, or project particles from the ground using cannons, to infuse the clouds.
Is cloud seeding effective against wildfires?
Some countries have tried using cloud seeding to put out wildfires.
In the United States, this was tested as part of the experimental “Project Skyfire” initiative in the 1950s.
Russia most recently used the method to battle forest fires in Siberian regions in 2020 and 2021.
Burger said the “jury is still out” on how effective this method can be to cause more rain and in the context of wildfires, the research is “still young.”
“There is still a lot of work that needs to be done for everyone to be convinced that this is possible,” he said.
Theoretically, the cold cloud seeding method could be applied over a wildfire region to enhance precipitation formation via the ice phase if the clouds are supercooled, Kanji said.
“I think if it’s found to be an effective tool for enhancing precipitation upon wildfires, then I think it could be used in Canada, it could be used in other places as well,” he said.
But there are “big uncertainties” with the approach, Kanji added, because of the danger of overseeding, which could have the opposite effect.
“If you inject too many of these particles, then you may form a large number of very small droplets that then don’t become big enough to fall down as rain or a large number of very small ice crystals were formed that don’t grow large enough to fall down as precipitation, as snow or rain,” he said.
Since 1996, only one company, Weather Modification Inc., has reported undertaking weather modification activities through cloud seeing in Canada, said Environment and Climate Change Canada spokesperson Nicole Allen. It operates a hail suppression program in Alberta, she said.
“In an effort to reduce hail damage, the company introduces a seeding agent, silver iodide, into some of the thunderstorms that develop in the Calgary-Red Deer area between May and September of each year,” Allen told Global News.
So far this year, a total of 1,483 wildfires in Canada have burned roughly 516,980 hectares of land, according to the Canadian Interagency Forest Fire Centre.
— with files from Global News’ Nathaniel Dove and Reuters.