Ottawa

Ottawa's weather to get warmer, wetter and wilder: study

Climate change will cause Ottawa's seasons to shift noticeably, with shorter winters, less snow and a heightened risk of extreme weather including tornadoes, new projections show.

Report commissioned by city, NCC shows temperatures rising 1.8 C by next decade

According to climate projections, Ottawa could see more freezing rain and freeze-thaw cycles in the future. (Simon Lasalle/CBC)

Climate change will cause Ottawa's seasons to shift noticeably, with shorter winters, less snow and a heightened risk of extreme weather including tornadoes, new projections show.

The city and the National Capital Commission commissioned CBCL Limited to predict how the weather in the region will change, so they can start planning now to mitigate the effects.

According to the firm, there will be more heat waves and flooding, putting pressure on everything from emergency services to the foundations of buildings. The changing climate will also shorten the cross-country skiing season in Gatineau Park and the skating season on the Rideau Canal, according to the report.

Average temperatures in Ottawa are expected to rise by 1.8 C by the 2030s, by 3.2 C by the 2050s, and by 5.3 C by the 2080s, according to the 419-page report.

At the same time, the capital region could become wetter, with more intense precipitation in winter and the "shoulder seasons," although less of it is likely to fall in the form of snow. 

Winters could be four weeks shorter by the 2030s and eight weeks shorter by the 2080s, with far more freeze-thaw cycles between December and February, and fewer "deep freeze events."

Ottawa saw 11 very hot days per year from 1981 to 2010, when temperatures rose above 30 C, but there could be 25 to 28 such days by the next decade, and 36 to 72 of them by the 2080s. 

CBCL Limited predicts Ottawa's temperatures to rise. By the 2080s, the average temperature in January could be about what the average temperature was in March from 1981 to 2010. (CBCL Limited for National Capital Commission and City of Ottawa)

The projections become less certain the further they are into the future.

The consultant considered scenarios in which greenhouse gas emissions were moderate or high, leading to global warming of 1.8 C or 3.7 C, according to standards established by the United Nations' Intergovernmental Panel on Climate Change.

While Gatineau, Que., was not a partner in the study, the report states the findings complement work that city is doing with Ouranos, a non-profit made up of government agencies and universities. 

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