SCOTT DETROW, HOST:
Most of the U.S. could see record-breaking temperatures this week as a heat wave hits a wide swath of the country. This follows a record-breaking heat wave in Europe last week where temperatures in parts of the continent reached more than 100 degrees Fahrenheit. The World Health Organization has linked hundreds of deaths across the continent to high temperatures, with the French public health agency reporting more than 1,000 fatalities in France alone over the past few days. Scientists from the World Weather Attribution group, or WWA, say their research shows this is the most severe and widespread heat wave to scorch Europe ever. Theodore Keeping is part of the WWA team and a research associate studying extreme weather at Imperial College London and joins us now. Welcome.
THEODORE KEEPING: Hiya (ph).
DETROW: Obviously, we focus on the temperatures, and the temperatures are pretty extreme. They're pretty notable, but there's a lot of factors going on that make this especially deadly, right? What is the best scientific way to think about this?
KEEPING: Yeah. So lots of factors contribute to the temperature that you actually feel in your body and the heat stress people experience, and therefore the health impacts as well. The big additional factor is humidity because that affects the ability for your body to cool down with sweating through evaporation. We looked at something called the indoor wet bulb globe temperature, and that combines the effect of humidity and temperature to look at how the body is capable of cooling itself down. And what we found is that in about 45% of cities that we analyzed in Europe - that's about 854 cities there are in Europe, and about 45% of those, the wet bulb globe temperature was broken or forecast to be broken...
DETROW: Wow.
KEEPING: ...Just in this heat wave.
DETROW: You know, you are well aware of how politicized the question of climate change often quickly gets. And given that and given how many different complex factors are at play here, what is the best way for us to understand why your team was so confident that this recent heat wave was directly tied to climate change?
KEEPING: We're able to answer that question using this scientific discipline known as attribution science, which is one of the many disciplines within climate science. And if you think about, say, temperatures, there's a whole distribution of temperatures that might happen in June from a pretty cold day through the average, and then to these very, very hot extremes. And what we're able to do is we're able to use observational data and climate models to understand how the distribution of temperatures at that extreme shifts as a response to a global average temperature. And what we were able to find is that since 1976, this event has gone from one that people would just not experience in, you know, many lifetimes to one that you'd expect to see multiple times in the average lifetime.
DETROW: Is it accurate that Europe is currently the fastest warming continent on Earth?
KEEPING: Yes. Yeah, it is accurate, but maybe not in the way that it sounds. So the reason why Europe is the fastest warming continent is because it is on average the highest latitude continent. It's the closest continent, on average, to one of the poles. And so the reason why it's the fastest warming continent is because it started the coldest, right? So actually, the temperature extremes that you're hitting towards the equator are still higher than the ones we're seeing hit in Europe. And so, actually, if we go back to that idea of the physiological limits with the wet bulb globe temperature, we saw loads of records being broken this week in Europe, but those records are fairly normal, even, in some parts of the world that are kind of the humid tropics. So yes, Europe is stepping into a new climate. And it is warming very fast, and that does mean we really need to think about adaptation. But also, you know, climate change is pushing towards more dangerous extremes at lower latitudes as well.
DETROW: We are seeing that in just the last few days alone French authorities are reporting more than 1,000 fatalities. How worried are you that this is going to be another deadly summer?
KEEPING: I am concerned. I think it would be extremely surprising if there hadn't been a very high death toll of this heat wave, also the May heat wave we experienced that was also record-breaking, and we know that early season heat waves kill more people. People are less adapted to the heat. There are more vulnerable people in the population, sadly. And the reality is, is that we know from the science that the increase in the temperature of heat waves that we see due to climate change, you know, it's sometimes two degrees, three degrees on average for the temperature of heat waves in Europe. We know that that causes extra death. So we know that these heat waves are going to have killed people, and we know that they're going to have killed much more people than they would have due to human-caused climate change as well.
DETROW: That is Theodore Keeping, a research associate in the analysis of extreme weather and wildfires at Imperial College London. Thanks for walking through all of this with us.
KEEPING: Thanks, Scott. Transcript provided by NPR, Copyright NPR.
NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.
