ROBERT SIEGEL, HOST:
The East Coast is hunkering down for its first snowstorm of the season, but we're going to talk about how hot it is right now. Today, NASA and the National Oceanic and Atmospheric Administration, NOAA, confirmed that 2015 was the warmest year since record-keeping began in 1880. The global average was nearly a fourth of a degree Fahrenheit higher than in 2014 - 0.23 degrees, to be exact. Is that a big deal? Well, we asked Deke Arndt of NOAA's climate monitoring branch.
DEKE ARNDT: Well, that is a big deal. If we do set new records, and we've set them three or four times already this century, we set them by hundredths of degrees. So .23, that's big. That's a really big step up.
SIEGEL: How, actually, do you take the temperature for the entire planet?
ARNDT: We collect data from the different weather services around the world over land. At sea, we have ships and buoys that report temperatures. We compile those. And NASA compiles them in a slightly different way. We compare those to the historical averages and we get a good indication of where this year ranks in comparison to history.
SIEGEL: If we saw a graph of temperatures since 1880, would we see it going sharply up over the last 10, 20 years?
ARNDT: Over the last 30 or 40 years, you would see the arch bend upward. From one year to the next, you would see some steps up and some steps down. But over the course of that 30 to 40 years, it has risen sharply.
SIEGEL: Twenty-fifteen saw several extreme weather events - powerful hurricanes off the coast of Mexico, drought in California followed by the heavy rains there. Is there a connection to the numbers that you're reporting today and those extreme events?
ARNDT: In a big-picture, statistical sense, yes. It is difficult to connect a single extreme event to climate change, but we know when we run the statistics on the aggregate, you know, of how many of these events or how strong are they on average or how frequently do they occur, we do see increases in big heat and in big rain, especially, and in some cases, big drought as well.
SIEGEL: It was a big year for El Nino. How much of what you're reporting is about El Nino and how much of it is about climate change?
ARNDT: Well, as far as global temperatures, they work together. It's not one or the other, it's one with the other. One good analogy would be the long-term warming is like riding an escalator up over time consistently. And the El Nino phenomenon is like jumping up and down while you're riding that escalator. So at the end of the escalator if we've had decades of warming and we jump up high from that step in an El Nino period, we're going to reach new heights.
SIEGEL: There is a lot of rhetoric about climate change. I wonder for you, what do these numbers tell you that the broader discussion might miss?
ARNDT: Well, that's the great thing about being in science is, you know, we are guided by the numbers, by the data, by the output, by what we see. What the numbers this year tell me, it's basically an exclamation point on several decades of warming. So we had a really warm year, and that by itself is an interesting fact. But when you couple that with the fact that we've been warming consistently for the last 30, 40 years globally, you know, it really drives home that we are living in a warmed world. We're living in a changed world. We're living in a changing world. So this is the planet that we're going to hand to the next generation. It's going to be under changes that are, you know, more rapid than we've seen in modern civilization.
SIEGEL: Deke Arndt of NOAA's climate monitoring branch. Thank you.
ARNDT: Thank you.