Climate Change at Home

In Al Gore’s latest movie, An Inconvenient Sequel: Truth to Power (2017), I was struck by the image of a plot of summer temperatures moving to the right as time progressed. I thought I’d see whether that shift held true for downtown Toronto.

Environment Canada has Toronto temperature records going back to 1840. I chose to begin in 1848 so I could group the data into decades ending at the end of 2017. Conincidentally this was the start of the industrial age – when our global climate started to change. Here’s a plot of average daily summer temperatures for 17 decades, from 1848-1857 to 2008-2017.

I’ve highlighted days 25 degrees or warmer. Clearly, there are more of them more recently. Still, the pernicious thing about climate change is how omnipresent and gradual it is. It’s kind of hard to see the warming shift. However, if I just isolate the first and last decade it becomes clear.


Summer in downtown Toronto is on average 3.2 °C warmer than it was 170 years ago. That’s pretty striking considering that the planet as a whole in all seasons is about 1.1 °C warmer

I get it when Bill McKibben says:

Every single day, climate change is the most important thing happening on the planet—there’s nothing even remotely close.