By: Luke Faulks, Opinions Editor

As of January 18, 2023, the openly climate-denying Canadian Conservative Party is leading the Liberals by 7%. And while the election’s a while off, Pierre Poilievre’s rise leads us to ask, again, how do we talk to a climate denier? 

Let’s try talking to them about global cooling. It’s a way to reinforce the power of the scientific consensus around warming and teach about the link between atmospheric CO2 and temperature. 

The concept of cooling is often brought up by climate deniers to discredit science, but engaging with them on the issue can actually help underscore the validity of the scientific method. When deniers talk about global cooling, it usually goes like this: “If you look into the 1920s, they were talking about a global freezing, okay?” That’s a quote from former President Trump, and, apart from the year, it’s a classic climate denier line. He’s reflecting a view that’s often repeated by climate deniers, which is that, “back in the day,” usually the 1970s and 1980s, scientists were convinced the world was on a cooling trajectory. If scientists were convinced and wrong back then, the argument goes, maybe their conviction might be wrong on climate change now.

The real story is easy to convey and helps to underscore the validity of the scientific method. The “global cooling” fear stems mostly from just one extremely popular article published by Newsweek in 1975. But the article’s findings weren’t substantiated in academic journals at the time, and the author has since recanted the piece, expressing regret that his work had been used by climate deniers for decades.

A 2008 review of research published between 1965 and 1979 found that, even then, scientists were more concerned about global warming than cooling. Case in point, in 1975, the same year that saw the publication of that Newsweek article, there was no published scholarly research confirming global cooling. But there were around 40 studies on warming. Now, around 99% (or 97%, or 100%) of research published confirms a massive consensus on global warming. Consensus-building using the scientific method works, and it was crushing junk science like global cooling before Newsweek even published its piece.

But there’s another reason to talk about global cooling, and that’s because global warming is making global cooling impossible.

Climate deniers are right about one thing: “the climate is always changing.” It always has, and CO2 has always been a big part of that change. CO2 plays a critical role in regulating temperatures on earth. When there’s a lot of CO2 in the atmosphere, more of the Sun’s energy gets trapped and rebounds to the planet, heating the earth. When CO2 falls, the temperature falls, which contributes to ice ages (though the planet’s orbit is the bigger culprit). A graph from the think-tank Carbon Brief shows the link between temperature and CO2 in action. It shows how CO2 and temperature have risen and fallen in sync over time, but are overall rising. 

High points on the graph correspond with melting periods, and low points match the planet’s ice ages. It’s a fantastic visual way to show the role that CO2 plays in regulating the earth’s atmosphere; it’s also a way to get them on-side. Yes, the climate has always changed, and yes, there are global warming and global cooling periods, but those temperatures are tied to global CO2 levels. That’s the time to notice the right-most part of the graph, better shown by this table from NASA, and the massive spike in CO2 emissions that it shows. That’s due to human activities. If not for that spike, a paper published in 2012 suggests that the next millennium could have seen the next ice age. But we’ve interrupted that natural cycle by pumping too much carbon into the atmosphere. Our hands are on the wheel now. And the notion of global cooling is an effective way to force that realization. 

Arguing with a climate denier can be tedious. It can be enraging. But by raising the idea of global cooling, you can take the wind out of your sparring partner’s sails, help reinforce the validity of climate science in a, maybe, novel way, and tie changes in global temperatures to atmospheric CO2. In short, the concept of global cooling may be one way to emphasize the very real threat of global warming to a skeptic.