I was asked the other day if the heat wave we are experiencing is a consequence of climate change.
You would think that would be an easy question to answer. Warmer climate, more high temperature events.
But it is not that simple nor casually related. While climate change is happening and slowly increasing the mean average surface temperature of the Earth, day to day weather cannot simply be attributed to the overall changes in climate.
Climate is a trend; weather is a single data point. Weather is the noise in the system.
Because I teach chemistry, let’s try this analogy involving a quiz. Let’s assume I have 100 students in a class and they take a quiz worth 20 marks. The class average might be 12.6.
Did anyone actually get a grade of 12.6? No. Their grades were whole numbers so it was impossible for anyone to actually get 12.6. More to the point, some students did way better than 12.6 and some did worse. Indeed, grades for each student could range from 0 to 20.
The scores of the individual students are like the weather. Unpredictable and sporadic. Although you might have a sense of how a particular student might do, you couldn’t actually predict the results accurately. Students surprise you and so does the weather.
We had a particularly cool spring. March and April were not warm months but they’ve been followed by a hot May. The weather has been like the test scores – varying from day to day. And with it, the temperature has jumped around.
But the overall trend gives us an average score. That is the climate. The overall picture of the weather, rounding out the spikes up and down.
In the case of our chemistry class, it would be like looking at the average score on that quiz for every year the course has been taught. We find that 20 years ago, the class average was 12.1 and each year it has crept up a bit … 12.15, 12.2, 12.25, etc. We are now at 12.6. Students are getting better.
If we look at the average temperature for the past one hundred years, it has steadily increased by 1.1 Celsius over that time. And that is our changing climate.
Todd Whitcombe is a chemistry professor at UNBC.
