More mild days for Canada due to climate change, says study
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Meteorologist/Science Writer
Monday, February 27, 2017, 7:35 AM - Canada may become something of a safe haven from climate extremes, as a new study says climate change should deliver more mild weather days across much of the country.
Climate change is already influencing global weather patterns, pushing temperatures, precipitation amounts and humidity levels to new extremes at both ends of the spectrum.
According to a new study, while this trend is making days with mild, pleasant weather more scarce on a global scale, in some isolated parts of the world, such as Canada, a warmer world may actually make these mild days more common.
This is not a particularly new concept, as scientists have long known that countries at higher latitudes would experience more warmer days during the year, and this could result in a net benefit for at least those regions. This new study, however, led by Princeton University researcher Karin van der Wiel and published in the journal Climate Change on Wednesday, specifically examined how climate change would affect what most people identify as "nice" weather, as opposed to looking at the extremes.
"We looked at the actual days that feel mild," van der Wiel told the Canadian Press. "These are the days that people can relate to -- the day you had a really nice walk in the park or went to a baseball game and it was really nice."
In this study, a "mild day" is one defined as having:
• a daily high temperature of between 18oC and 30oC
• total daily precipitation of less than 1 millimetre, and
• an average dew point temperature of 20oC or less.
This combination results in a day that is warm, but not too hot, with little to no rainfall, and with humidity levels that are comfortably dry both day and night.
From a global perspective, van der Wiel and her colleagues found that, per square kilometre, there is currently an average of 74 mild days per year, and that global warming would cause an overall loss of 4 mild days per year by 2035 and a loss of 10 mild days per year by the end of the century.
Change in number of "mild days" by 2081-2100, showing an average global loss of 10 days per year per square kilometre, or 11 days per year per person when taking population density into account. Credit: van der Wiel, et all, 2017.
Zoom in on Canada, though, and the effects are mainly positive, with an increase of between 5 and 25 mild days per year across much of the country. Other regions of the world that are also expected to see an increase in mild days include Europe, parts of the Middle East and central Asia, the southern coastline of Australia, isolated pockets in eastern and southern Africa, as well as Madagascar, and down along the mountainous regions of Mexico, Central America and South America.
This isn't entirely good news, of course, even for Canada. While eastern Quebec and parts of Atlantic Canada will be able to enjoy more mild days, many of the areas that will see these increases are sparsely populated, or places where we really don't want to see more mild weather - such as across normally snowy mountaintops or encroaching on regions of permafrost in the north. Added to the net loss of mild days in much more heavily populated areas - mainly due to extreme heat and humidity, and extreme precipitation events - this is simply not good news for the future of human civilization.
Still, the purpose of this study was to come up with a way for people to "feel" the changing climate in a way that's easier than tracking extreme weather events.
"It's really difficult to feel that what was a once-in-25-year event is now a one-in-20-year event," van der Wiel told the Canadian Press. "I think this 'mild day' that we came up with is easier to relate to."
Sources: Canadian Press/CBC | Climate Change
