ARI SHAPIRO, HOST:
High temperatures have broken records all over the U.S. this summer, and we know that climate change will make heatwaves more frequent and more extreme. Now a study suggests that the rate of global warming increases the probability of extreme temperatures. Atmospheric scientist Jennifer Francis joins us to discuss this study published in the journal Nature Climate Change. She is a senior scientist at the Woodwell Climate Research Center in Massachusetts. Welcome.
JENNIFER FRANCIS: Thank you for having me.
SHAPIRO: So previous studies have established the relationship between global warming and heat waves. How does this new research about the rate of global warming advance our understanding?
FRANCIS: It puts a bold exclamation point on what we already know, and that is that heat waves are going to get more intense. They're going to last longer in the future as we keep dumping greenhouse gases into the atmosphere. And this is incredibly timely following the heat wave that occurred in the Pacific Northwest in June that literally smashed records.
SHAPIRO: Yeah.
FRANCIS: So they looked at how these really extreme events would change in the future as - in different scenarios of the future.
SHAPIRO: So let's talk about what those scenarios showed. I mean, if we don't limit our current emissions, like, what's going to happen?
FRANCIS: Yeah, so what they found was these record-smashing events would increase in frequency or probability by something like two to seven times in the next 30 years.
SHAPIRO: So more than twice as many, up to seven times as many.
FRANCIS: Exactly. So this would be a huge increase. And then going beyond that into the future, those probabilities just get even larger, so up to 21 times more likely somewhere around the northern hemisphere.
SHAPIRO: Does this mean that looking to extreme temperatures in the past are going to be a poor guide to the future since the Earth is now warming so much more quickly than it was 100 years ago?
FRANCIS: It certainly does mean that. And there are many aspects of the way the climate is changing that the past really is not very helpful anymore because we're literally in uncharted territory in many ways.
SHAPIRO: But if the rate of warming is significant beyond just the temperature of the Earth, what does that mean if we limit greenhouse gas emissions and stop putting carbon into the atmosphere?
FRANCIS: Yeah, so this is something we absolutely have to do. We have to do it as fast as possible and as dramatically as possible because if we can turn our emissions around and literally get to the point where we are not adding more greenhouse gases to the atmosphere anymore, we can make this probability of record-smashing heat events like the one we saw this summer - they'll still happen more often, but they won't be as common as this research suggests it could be in the future.
SHAPIRO: I just have to ask about the definition of a record-setting heat event because once a record is broken, the new record is higher than the old one. Are you talking about constantly breaking new records, and so we're hitting temperatures that are hotter and hotter and hotter?
FRANCIS: That's exactly what this means. And that was another really interesting aspect of the study because they looked at these record-smashing events, and as you say, they build on each other. So once you set a new record, then a record-smashing event has to exceed that. So this information is telling us that, really, the situation is even worse than we thought. And it also tells us that there's hope because if we are able to slow down our emissions, which would in turn slow down the rate of warming of the globe, then we could make this situation much less bad than it would be otherwise.
SHAPIRO: That is Jennifer Francis, senior scientist at the Woodwell Climate Research Center in Massachusetts. Thank you for speaking with us.
FRANCIS: You're very welcome.
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