Climate researcher on what’s causing the record rise in ocean temperatures

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• Amna Nawaz:

  The World Meteorological Organization issued a red alert warning today about warming and climate change, saying 2024 is shaping up to be another record year.

  As William Brangham details, one of the many worries about how the planet is changing, thanks in part to human activity, is the record-shattering warming of the world's oceans.

• William Brangham:

  I want to put up a graph that shows just how out of the ordinary ocean temperatures are becoming.

  This shows the averaged daily surface temperatures of the world's oceans. Those very thin gray lines each represent one year, going back to 1979. Now, here's last year's readings in orange; 2023 started out at the upper end of normal, but soon became a record-breakingly hot year. And here in red is just the beginning of this year. The oceans are already in uncharted territory.

  So, what is going on here? John Abraham is a professor of mechanical engineering at the University of St. Thomas and is part of an international consortium of researchers who monitor ocean temperatures.

  John Abraham, thank you so much for being here.

  Before we get into the why, I wonder if you — are you in this camp that is genuinely alarmed at what's going on?

  John Abraham, Professor and Program Director, Department of Mechanical Engineering, University of St. Thomas: Well, that's a really good question.

  So, behind the scenes, there are two groups of scientists. One group thinks that what we're seeing can be explained by long-term global warming and what's called an El Nino. And then there's another group who think there might be another ingredient involved. There might be something that we haven't detected yet.

  And I hate to say it. I'm sort of in the middle. I — the warming that we are seeing this past year is a little out of the ordinary of what we would expect with global warming and El Nino together. Maybe something else is happening, but we don't know. And this is what makes scientists excited. And this is what makes science great.

  We like to uncover these question marks. But there is a question mark. And I — to be honest, I'm on the fence.

• William Brangham:

  OK, so let's unpack that, though.

  On climate change, in particular, as we warm the atmosphere, the oceans do get warmer. We know that that's a pretty well-documented fact. El Nino, as you mentioned, we're on the tail end of one of those. That can warm the oceans as well.

  If you had to put these as a percentage, are we principally talking about climate change here, or how do you apportion blame here?

• John Abraham:

  Well, if you want me to quantify the effect — and this is just off the cuff. This is a rough estimate based on my intuition. I'd say it's about half global warming, and maybe a third of it is El Nino.

  And then the remainder, maybe 20 percent or so, is a question mark. And that 20 percent could be some extra global warming that we hadn't accounted for, but it could be something else. But the majority of this, and the real reason we're setting records every year, is global warming.

  But, as you pointed out, this year is a — the scientific term is bonkers year. This is off the charts. And it's more than we would have normally expected, even with an El Nino.

• William Brangham:

  So there's a couple of other factors that I have read about being possibly complicit here, this huge volcanic eruption that happened a while ago that spit a ton of moisture up into the atmosphere, which can warm the atmosphere, solar cycles.

  Also, the elimination of a lot of pollution from shipping, which, paradoxically, it's wonderful for human health, but it's taking this umbrella off the oceans, which can also warm the oceans. Are those factors that you consider as well?

• John Abraham:

  They could be. And some scientists are considering those.

  I'm not sold. And the reason I'm not sold is, we're seeing an incredible amount of heat in specific locations and, in particular, in the Atlantic Ocean. And we're seeing other parts of the planet that have lower surface temperatures.

  So, the patterns of warming that we're seeing aren't — don't jibe with some of the other options that you just mentioned, but they are under consideration by my colleagues.

• William Brangham:

  For people who might look at the chart that I showed and say, oh, well, you're just using a very narrow Y-axis, and why do we care if there's just a degree or two difference in temperature in something as colossal as the ocean, I mean, why do we care if the oceans are warming globally?

• John Abraham:

  You said it. The oceans are colossal.

  And there's an old idiom. It's a watched pot never boils. And that's really true. It takes a lot of energy to heat up water. And if that's true for a pot on your stove, think of how true it is for the oceans that cover 70 percent of our planet. Frankly, the amount of heat that has to go into the oceans to raise their temperature a degree Celsius or even a degree Fahrenheit is astronomical.

  So, a degree warming of the ocean, man, that's a different world. And it's going to affect the weather all over the planet, tremendous impacts to humans and our society. So these numbers, in terms of temperature increases, are really astounding.

• William Brangham:

  My colleague mentioned the World Meteorological Organization issuing this red alert.

  And we ask people this often, but I just wonder what your take on this would be, which is, given these findings, what is it we ought to be doing as humanity to try to address this?

• John Abraham:

  Oh, that's the easy part.

  We need to just do a couple things, and we can do them today with today's technology. First, we need to conserve energy. Just use energy more wisely. Let's not waste our — the energy that we get out of fossil fuels. Conserve.

  Secondly, maximize our development of clean and renewable energy. And the great thing is, green energy is now cost-comparable to fossil fuels. So, in the olden days, if you put solar panels on your house, that was a mark of altruism. Now it's a mark of fiscal conservatism. Clean energy is now cheaper than coal.

  And that has really created an inflection point in the scientific community. That's what gives us optimism. There's no longer any reason not to maximize clean, renewable energy. So those two things are the most important things that people can do to change the trajectory that we're on.

• William Brangham:

  All right, John Abraham, professor of engineering at St. Thomas University, thank you so much for being here.

• John Abraham:

  Pleasure.