This summer’s heat wave and wildfires weakened the landscape’s ability to absorb rainfall, further contributing to the destruction.
- Flooding in British Columbia has displaced over 18,000 residents. The catastrophe resulted in several fatalities, and is estimated to leave the province with a bill of over $1 billion.
- Natural hazards earlier this year set the stage for disaster. This summer’s extreme heat wave and wildfires weakened the landscape’s ability to absorb water, increasing the risk of floods and mudslides when the torrent began.
- The rains were the result of a weather phenomenon known as an “atmospheric river,” a narrow column that transports water vapor from the tropics to the poles. Atmospheric rivers are projected to intensify as the climate continues to warm.
By Laura Gersony, Circle of Blue — November 22, 2021
Thousands of feet above British Columbia, disaster was brewing. A 2,600-mile-long column transporting moist air from the tropics to the poles, known as an “atmospheric river,” arrived over the province early last week. As the downpour began, rainfall quickly gave rise to catastrophe.
For days, the region was battered by a deluge that swept away automobiles, displaced over 18,000 residents, and snapped some highways in two. Some areas of British Columbia received in a single day the amount of rain that usually falls in a month. For several days last week, the three main roadways into the city of Vancouver were impassable, with rail closures expected to last for months. It might be the most expensive natural disaster in Canadian history.
Krystal Babcock, a resident of Merritt, British Columbia, was unable to leave her home when the government ordered residents to evacuate on Monday, staying back to care for her elderly parents who could not leave. The sheer intensity of the flood left her in shock.
“The water has never done anything like this. I would have never thought that that water could come that fast … There was no time before the town was turned into a river,” Babcock told the Guardian.
Atmospheric rivers are not uncommon in the region. Most of them are beneficial, bringing about 30 to 50 percent of annual precipitation on the West Coast. But this one was unusually powerful. There are three main factors why, climate scientist Simon Donnor explained to the Globe and Mail. The volume of air in the atmospheric river’s column; the La Niña weather pattern, which created conditions conducive to transporting water; and the fact that it lasted for three full days.
“There are times you can feel the atmospheric river effects for a couple days in a row, but this level of intensity was incredible,” Donner said. “It was like being in a tropical hurricane, in terms of the rainfall.”
Natural hazards earlier this year set the stage for disaster. This summer’s extreme heat wave sucked moisture out of the soil, which made the landscape a tinderbox for wildfires that followed. When heavy rain began to fall, denuded and scorched soils weakened the landscape’s ability to absorb water, increasing the risk of floods and mudslides.
To make matters worse, British Columbia and Washington had already seen a rainy autumn.
“The soil was already saturated when this rainfall event came,” said Jeremy Venditti, a professor of environmental science at Simon Fraser University. “And so the water had nowhere to go but run off into rivers, ditches and creeks.”
The past few months have been marked by the accelerating cycle of disaster in the region — a hallmark of a changing climate. Each event hits before humans and the natural environment have time to regain their footing, compounding the damage. The town of Lytton was mostly destroyed by a wildfire in June; last week it was covered in water. Climate change is projected to intensify atmospheric rivers across the globe. Moving forward, experts say, adaptation is paramount.
“We know they’re going to happen more frequently,” said Joanna Eyquem of the Intact Centre on Climate Adaptation, “so we need to move into emergency mode.”
Laura Gersony covers water policy, infrastructure, and energy for Circle of Blue. She also writes FRESH, Circle of Blue’s biweekly digest of Great Lakes policy news, and HotSpots H2O, a monthly column about the regions and populations most at-risk for water-related hazards and conflict. She is an Environmental Studies and Political Science major at the University of Chicago and an avid Lake Michigan swimmer.