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Flooded streets in Abbotsford, Canada
Photo: JENNIFER GAUTHIER / Reuters
The military flies people out, the metropolis of Vancouver is almost cut off from the outside world and the prime minister begs the population to stop buying hamsters: After days of rain, floods and mudslides, Canada's west coast is in a state of emergency.
The government is now sending more soldiers to ensure the supply of drinking water.
More than 17,000 people have already had to leave their homes due to flooding.
Highways and a rail link to Vancouver were closed.
The Canadian west coast metropolis could only be reached from the USA.
Access to the country's largest port in Vancouver was also interrupted.
"We assume that there will be even more fatalities in the coming days," said John Horgan, British Columbia Prime Minister.
The floods are an event that only occurs every 500 years.
It's not the first extreme weather event this year on Canada's west coast.
During the heat wave in the summer, temperatures in the region rose to more than 49 degrees, hundreds of people died, mostly in the greater Vancouver area.
A so-called heat dome was located above the region at that time.
Such heat domes arise when areas of high pressure establish themselves and store the heat there.
The torrential rains of the past few days are due to a weather system called "atmospheric flow".
These celestial rivers can be thousands of kilometers long and transport enormous amounts of moisture, initially in the form of water vapor, from the subtropics to the north.
In cooler regions, the water vapor condenses and forms rain clouds.
The heavy rains, which reached into the northwest of the USA, came with the so-called »Pineapple Express«.
This is the atmospheric river that carries warm water vapor from near Hawaii to the west coast of North America and in this way supplies parts of the continent with water and repeatedly causes flooding.
In the future, the rivers in the sky could bring significantly more rain from south to north due to global warming.
This is suggested by computer simulations from Yale University, which were recently published in Nature.
This increases the risk of extreme weather events such as floods in entire regions.
In coastal regions in particular, the risk of storms and floods is increasing, the researchers write.
After forest fires, the soil absorbs less water
In the severe weather zone in British Columbia, it not only rained for more than 24 hours in a row, the intensity of the rainfall was also well above average.
At some measuring points, old records for amounts of precipitation were exceeded by a factor of two.
The river levels were high anyway, after it had rained a lot in October and early November.
The soils could not absorb much additional water either.
Two other factors caused even more water masses: The warm rains caused snow to melt at higher altitudes, which led to the subsequent floods.
And in forests, where devastating fires raged in the summer, the soil is often hydrophobic - it repels water instead of absorbing it.
While the Pineapple Express is the best-known example, there are also sky rivers in Europe that are often associated with extreme weather.
A study by the University of California showed, for example, that particularly heavy rainfall in Great Britain, France and Spain can be attributed to such phenomena in almost half of all cases.
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