2023 beats record for hottest year on record by larger than expected margin

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• Amna Nawaz:

  2023 was the hottest year on record, by a long shot.

  Europe's top climate agency released data today showing global temperatures averaged 1.48 degrees Celsius or 2.66 degrees Fahrenheit above preindustrial levels. Record high temperatures are expected to continue this year.

  For more on the implications of this record heat, I'm joined by Radley Horton. He's professor at Columbia University's Climate School.

  Radley, welcome back.

  So, the planet didn't just set a new global annual heat record. It shattered previous records. Did we expect to see that kind of increase this quickly?

• Radley Horton, Columbia University Climate School:

  No, we did not.

  At this point, we have gotten used to seeing records as warm as any prior year. We have gotten used to hearing this is the ninth straight, the nine last years have been the nine warmest on record. But what we had happen this year is that, over the last six months, we were half-a-degree Fahrenheit height warmer than any of those previous years.

  So you could think of it like all the previous years were stacked pretty close together. And along comes a year in 2023 where the last six months were a full half-a-degree warmer than any of those previous years. So this was not expected.

• Amna Nawaz:

  So how do we account for that? What drove that increase this past year?

• Radley Horton:

  Yes, well, we have to start — there's a few factors, but we have to start with human activities, the burning of fossil fuels.

  We're putting so much more heat in the system, and there's growing concern among scientists that we may have underestimated just how sensitive the climate, the Earth's temperature is to greenhouse gases as they increase. Are models missing some processes?

  But there are some other things going on besides that — those human activities. We had a very — a moderately strong El Nino that's under way right now. That can be responsible for some warming of the planet, but not this much. And then, similarly, we had a volcanic eruption under the ocean that actually put water vapor up into the atmosphere, which, unlike most volcanoes, is effective to some degree at warming the planet, but, again, couldn't anywhere come close to explaining this degree of shattering of previous records.

• Amna Nawaz:

  So we know global warming doesn't just mean more heat and hotter records. We know it also means more extreme weather events. Where have we been seeing those? Where is it becoming real for these communities?

• Radley Horton:

  Yes, and there's so many examples.

  I will highlight some of the cases where the records got shattered, just as the global average temperatures did. You look at the degree of some of these heavy rain events, these tragic floods in 2023, like we saw in Libya, for example, in Greece, certainly heat waves front and center, right?

  We saw exceptional heat across Southern Europe, across China, across the Southern U.S. So this is hugely impactful for our economies, for our ecosystems. How about the forest fires that we saw across Canada? By some estimates, four times more burned area than ever before seen in Canada. It's directly related to the planet warming, more than we thought it could, causing the air to dry out and essentially suck moisture out of that vegetation, priming the pump for these really extreme fires.

• Amna Nawaz:

  And we should underscore, we're talking about deadly events here. You also mentioned the economic component.

  I want to point out the U.S. alone had 28 weather disasters last year. The combined damage killed 492 people and caused nearly $93 billion in damage. In short, can we afford to continue at this pace?

• Radley Horton:

  Well, no, we can't.

  We have to urgently reduce our greenhouse gas emissions. That's clearer than ever. We can see it by looking at the damages this past year, economic and loss of life and some of those things that don't get captured by metrics like GDP.

  But the additional concern, as you note, because this year was so much warmer than prior years and because of growing evidence that we may have underestimated how vulnerable we as a society are to a little bit higher temperatures, it's becoming clear that, if we want to avert these worst-case scenarios and possible really catastrophic outcomes that are beyond what our climate models or our financial models or our crop models tell us is possible, we need to urgently reduce emissions and we have to adapt to these climate changes that are under way.

• Amna Nawaz:

  Radley, that 1.48 degree increase is just barely below the 1.5 degrees limit that the world agreed upon as what they would like to avoid to, as you mentioned, avoid those worst-case scenarios and the most severe outcomes.

  We talk about the tipping point a lot. Is this it?

• Radley Horton:

  Well, I'd say we don't need to focus exactly on 1.5 degrees.

  Really, the key takeaway, I think, is that we are failing terribly at reducing our emissions. But you're right that it's becoming more and more clear than it was just, say, five years or so ago that getting to 1.5 degrees is catastrophic for society. We have underestimated how vulnerable our systems are. We have underestimated how quickly these extreme events like heat waves and heavy rain are going to change.

  So, in that sense, whether it's a tipping point or not, we're way more vulnerable than we realized, and it's even more urgent than we thought that we dramatically reduce our emissions.

• Amna Nawaz:

  Radley Horton, professor at Columbia University's Climate School, thank you so much for joining us.

• Radley Horton:

  Thank you.