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Can we blame climate change for B.C. ‘atmospheric river?’


December 2, 2021   by Greg Meckbach


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We can’t say for sure that climate change has caused the heavy rainfall and severe floods and landslides currently affecting British Columbia, but global warming is making disasters like this more likely, a Swiss Re speaker suggested Thursday.

“Warmer air can carry more moisture, so there is generally this notion that the frequency of heavy precipitation events – essentially in most regions of the world – would be increasing” due to global warming, said Andreas Weigel, weather peril lead at Swiss Re, during a CatIQ Connect panel.

Moderator Kimberly Roberts, senior vice president at Guy Carpenter, asked panelists how they think climate change affects specific perils that are most important to Canada.

With global warming, temperatures get higher, so one might argue winters might get milder and heat waves might get hotter, said Weigel.

“If you look at the German floods this [past] summer – and the atmospheric river that happened in Canada just now – we cannot say that this is climate change, but we can say that climate change makes such events more likely,” Weigel said during the noon panel, titled Secondary Peril Problems and Solutions: Data, Monitoring, and Modelling.


Weigel was alluding to a disaster that Aon estimated this past July to have caused total economic losses of US$25 billion. Extreme precipitation in July of 2021 resulted in the costliest European flooding event on record, Aon said this past July in its global catastrophe recap. Among the most badly-hit areas were the Nordrhein-Westfalen and Rheinland-Pfalz states of Germany, with the official death toll listed at 197.

On Canada’s west coast, there were 12 evacuation orders involving 350 homes from Boston Bar to Abbotsford, B.C, The Canadian Press reported Thursday.

As of Thursday, flood warnings are in effect for the Coquihalla and Chilliwack rivers as well as the Lower Fraser tributaries and the Tulameen, Similkameen, Coldwater and Lower Nicola rivers.

Southern and coastal British Columbia have entered the tail end of severe weather that meteorologists have described as a “parade” of storms, CP reported.

A report released this past August concludes that the emission of greenhouse gases from human activities is responsible for about 1.1°C of warming since the period of 1850 to 1900. Averaged over the next 20 years, global temperature is expected to reach or exceed 1.5°C of warming since that period, according to Climate Change 2021: the Physical Science Basis, released by a working group of the Intergovernmental Panel on Climate Change. The working group outlines a number of implications for North America, including a change in precipitation patterns, with more intense rainfall and associated flooding, particularly for eastern North America, as well as more severe droughts in many regions.

In a best-case scenario, there will be global rise in sea level of 0.28 metres, IPCC said in the report.

This means we can conclude that the risk of storm surge in low lying areas would be increasing, Weigel said Thursday during CatIQ Connect, produced by Catastrophe Indices and Quantification Inc.

Also on the panel was Tom Larsen, principal of industry solutions at CoreLogic.

“Climate is different than the weather because the weather volatility is what our clients are handling right now – the bad years and good years,” said Larsen.

Modelling severe convective storm systems is complex. With severe convective storm, there could be hundreds of tornadoes and hundreds of square miles affected, said Larsen.

Right now – unlike hurricane – the industry does not have an intensity scale for a severe convective storm, Larsen noted.