Climate Change and a Subtropical Canada?

Guest essay by F.J. Shepherd

Real climate change could be realized by having a region with a cold temperate climate transforming into a warm temperate climate. This article will explore what it would take to achieve such an event in Canada.

It might seem strange to have the words, “subtropical” and “Canada” in the same line, for as most Canadians and some others know, Canada is a very cold country. The annual mean temperature for Canada is 0.6°C, but you will not likely find that information in any public documents. I had to work that figure out with collected data.

Statistics Canada published a report in 2011 titled Temperature Trends in Canada that gave an ominous warning. Over the period from 1948 to 2009 for Canada: “The linear trend indicates an increase in mean temperature of 1.4°C over the 62 years in the record.”

Since global temperature rise is not quite 1° C in 135 years, Canada’s warming rate is almost three times as great.

The report`s findings, surely, was enough to make Canadians shiver in their boots for fear, was it not? Well, if Canadians were shivering in their boots, it was more than likely from the winter temperatures because Canada remains a very cold country.

The major climate zones in Canada are polar, subpolar, humid continental and oceanic. Almost 90% of Canadians live within the humid continental zone since most Canadians live in the southern part of the nation no more than 200 miles from the American border. This climate zone is virtually the same as that experienced within the US north eastern states and northern midwest regions, plus northern and eastern Europe, and large areas of Russia.

Following the Koppen/Trewartha climate classification system, the humid continental climate has the following characteristics:

(1) distinct 4 seasons with a warm to hot summers, and a cold winters

(2) precipitation is evenly distributed throughout the year

(3) mean temperature for the coldest month of the year is below freezing

(4) there should be from 4 to 7 months within the year that have a mean temperatures at or exceeding 10° C.

Within a warming trend, the natural progression would be for a humid continental region to climb to the humid subtropical climate classification. Fortunately, with the modifications done by Trewartha (1966) to the Koppen (1899) climate classification system, it has made the distinctions between climate classifications easier. The original Koppen climate classification scheme left the boundaries between some climates, somewhat vague.

I have lived in the Toronto Canada region of southern Ontario for the past 50 years. The Toronto area has one of the warmer humid continental climates in Canada with an annual mean temperature of 9.4° C. There is quite a range of annual mean temperatures possible within a humid continental climate zone. For instance, further west and north of Toronto on the Canadian prairies, almost 2,000 miles away lies the small Saskatchewan city of Melfort. Its annual mean temperature is only 1° C with its much colder winters and cooler summers. However, this cold little prairie town still resides within a humid continental climate zone even though its annual mean temperature is 8.4° C colder than that of Toronto.

Table 1: Toronto monthly mean temperatures, 1981-2010 data, in Celsius

Note in Table 1 for existing Toronto monthly mean temperatures that the coldest month, January, has a mean temperature below freezing, and there are six months wherein the mean monthly temperature is 10° C or greater. This is a typical humid continental climate configuration, added with the other features in that for Toronto, precipitation does fall relatively evenly throughout the year and we do have 4 very distinct seasons.

Now how do we convert Toronto to a humid subtropical climate? Pretty much everything is well in place except for temperature. In order to comply with the parameters to achieve a humid subtropical climate, we need to rid Toronto of monthly mean temperatures below freezing and increase from 6 months to 8 months wherein monthly mean temperatures is 10° C or more. That is easy. All we have to do is increase the monthly mean temperatures by a factor of 5.1°C and the mission is accomplished. Here is the result:

Table 2: Toronto monthly mean temperatures for a humid subtropical climate

After I performed this procedure in a spreadsheet, I wanted to check against a city in North America that is relatively close in distance to Toronto and that actually does have a “legitimate” humid subtropical climate. This is the control variable in the experiment.

In order to do so I had to search through nearby US cities because no city exists in Canada with a humid subtropical climate. I emphasized the word “legitimate” because I found that some cities, like New York NY, Philadelphia PA, and Wilmington DE may claim to have a humid subtropical climate but they do not really have one; although they do appear to be very close. The nearest humid subtropical climate I found was in Baltimore MD. Here is Baltimore’s current temperature scheme:

Table 3: Baltimore monthly mean temperatures, 1981-2010 data, in Celsius

Note that from April to December (9 months), the monthly mean temperatures for Baltimore and the projected Toronto temperatures are so very close. This satisfied me that if Toronto was to shift into a humid subtropical climate, the projections I made using the 5.1° C bump, is more or less what it would take. The spread of temperatures in my Toronto projections also seemed reasonable when compared with Baltimore’s current monthly temperatures.

An obvious question arises. Given the accelerated warming that Canada seems to be experiencing and which is almost triple the global warming rate, how long would it take for real climate change to come to Toronto Canada?

The answer is simply a matter of basic arithmetic. If the overall temperature rise for Canada as a whole continues on its present rate of 1.4° C every 60 years, it will take about 218 years for Toronto to achieve the needed overall temperature rise of 5.1° C. Now supposing that the rate of temperature rise in Canada triples what it has been doing for the last 60 years and rises at a rate of 4.2° C every 60 years. Toronto will still have a long time to wait for its humid subtropical climate – at least another 73 years.

However, there is another factor to consider. For if you peruse the report mentioned above from Statistics Canada, Temperature Trends in Canada, there are some charts that the report links to. You will see that Toronto resides in the defined Great Lakes and St. Lawrence region, and that the temperature in this region has not been rising at the overall Canada rate of 1.4° C, but rather closer to 0.6 to 0.7° C within 60 years. Of course that puts a whole new perspective on things since such a rate is half of the national rate. See Chart 1 in the Report. So we have to “adjust” those time-frames wherein 218 years becomes now 436 years, and 73 years becomes 146 years, waiting for Toronto’s humid subtropical climate to finally come.

Summary

The above was merely an exercise I went through to see what it would take for one of the warmer cities in Canada to change from a humid continental climate to a humid subtropical climate. It is feasible but it would take many, many years to occur and that is providing that the world keeps warming. I understand that some people think that such warming would be a tragic event, but for those of us who experience this cold temperate climate who live in Toronto, would love for it to change to a humid subtropical climate. For me the real tragedy is that such a change won`t happen soon enough, if it does happen at all.