THE ERA OF WEATHER EXTREMES IS UPON US: “It’s less usual to see an atmospheric river penetrate right past the southern tip of Vancouver Island … and then into the Fraser Valley, going as deep in as in the Fraser Valley, and we saw this one,” stated Charles Curry, Pacific Climate Impacts Consortium after British Columbia was battered by a record-breaking rainstorm (November 2021)
Note to Reader:
Charles Curry is the Acting Lead, Regional Climate Impacts at PCIC (Pacific Climate Impacgts Consortium), with a background in Earth system and regional climate modelling. His research interests include the effects of climate change on the hydrological cycle in Western North America, the added value of dynamical downscaling, observed and modelled climate extremes, the behaviour and downscaling of surface winds, simulations of global climate engineering, and the biogeochemical and radiative modelling of greenhouse gases.
Two years ago, Charles Curry co-wrote a paper suggesting extreme rainfall events would lead to peak annual floods of historic proportions by the end of 2100 in the Fraser River Basin.
Atmospheric Rivers Increase Future Flood Risk in Western Canada’s Largest Pacific River
“Snow-covered areas of the globe are particularly sensitive to global warming. Future projections using global climate models generally show that as the ratio of snow to rain declines, river flows peak earlier in the year with reduced volume,” wrote Charles Curry and his three co-authors in a paper published in January 2019.
“These models also capture the phenomenon of ‘atmospheric rivers’: long, meandering plumes of water vapor often originating over the tropical oceans that bring sustained, heavy precipitation to the west coasts of North America and northern Europe.”
The present-day frequency of landfalling atmospheric rivers on the Canadian west coast is projected to increase nearly fourfold by the late 21st century, with a proportionate increase in extreme rainfall events.”
“Our work is the first to directly investigate the impact of these ‘rivers in the sky’ on ‘rivers on the land’ using climate model projections. Focusing on the Fraser River Basin, Canada’s largest Pacific watershed, and using a business-as-usual industrial emissions scenario, we show that the basin transitions from one where peak flow results from spring snowmelt to one where peak flow is often caused by extreme rainfall.”
“Our modeling suggests that extreme rainfall events resulting from atmospheric rivers may lead to peak annual floods of historic proportions, and of unprecedented frequency, by the late 21st century in the Fraser River Basin.”
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Download a copy of Atmospheric Rivers Increase Future Flood Risk in Western Canada’s Largest Pacific River, published in 2019.
Severe impacts of flooding created by perfect storm of circumstances in southern B.C.
“The atmospheric river that passed through B.C., last week, which caused severe flooding that destroyed homes and highways, was only one factor that led to such significant damage throughout the province,” wrote Courtney Dickson, journalist with CBC News, in an article about the record-breaking storm that battered British Columbia in mid-November 2021.
“It’s less usual to see an atmospheric river penetrate right past the southern tip of Vancouver Island,” she quoted Charles Curry as saying, “and then into the Fraser Valley, going as deep in as in the Fraser Valley, and we saw this one.”
“That’s particularly dangerous,” he added, “because the amount of water that these atmospheric rivers carry is very large and they don’t really release that water until they hit some topography, some mountains where they have to rise and the air cools and all that moisture that can just fall out of the atmosphere as rain.”
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