TORONTO ONTARIO
The Toronto thermometer record starts in 1840 in Yorkville and is home to the only thermometer record starting before the late 1800’s. This gives us an opportunity to see a little further into the past and confirm that the cooler temperatures that lasted until 1900 were persistent over a climatic time frame.
The magnitude and persistence of the prolonged and significant cold period since at least 1840 is clearly shown. This is a significant and persistent trend in the Canadian database at large as we will see later. The data show an abrupt increase in both nighttime low (Tmin) and daytime high (Tmax) of about 3 degrees over a span of about 20 years from about 1880 – 1900. These warmer temperatures remain until present day. This looks like a climactic shift if ever there was one.
The data also show a significantly greater increase in the nighttime low temperature (Tmin), compared to the daytime high temperature (Tmax). Could this trend be the “Global Warming” we’re looking for?
Let’s dive in a bit.
The rise, or slope of the Tmin graph bears many similarities to the more familiar Average Global Mean Temperature. Tmin rises fairly steadily starting around 1900 thorough to the end of the record. The slope of Tmax however does not share any of these characteristics. Tmax is dominated by the rise in temperature around 1900 with a peak around 1945, same as the earlier example, Sydney, followed by a cool period around the 1970’s and rising again until present.
Toronto is obviously an Urban location, Yorkville, not far from the city core.
Let’s check for a rural station in the vicinity to compare.
Beatrice, indicated by the number 3 on the map, is about 150 kms. North of Toronto and really can be described as “In the Middle of Nowhere” fortunately, with a very high quality thermometer record back to 1870’s
Beatrice:
This is a much different looking record from the Toronto record over the same time interval . While Tmax, for both locations, have very similar trends with Beatrice not surprisingly showing a lower absolute value due to its more northerly location. Tmin however is another story, Starting around 1920 the values for Toronto Tmin climbed higher while Beatrice Tmin Beatrice did not.
Toronto Squeeze:
Beatrice Squeeze:
Toronto/Beatrice Overlay:
No matter how we slice it the only significant CLIMATE anomaly is the temperature increase at the beginning of the 1900s.
This stark difference between the Toronto and the Beatrice locations raises the question of just how this apparent inconsistency would be dealt with when attempting to model past climate data.
This leaves the most important question: Are we measuring urbanization or are we measuring Climate?
This is a question that can be answered. There are enough quality records in SW Ontario and it is the topic of the next installment of “From The Desk of Shifty”.