Q&A: The Dire Consequences of Global Warming in the Earth’s Oceans

Imagining a world without fish in the world’s tropical oceans.

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A view of a toxic algae bloom on the shores of Guadeloupe. Credit: Loic Venance/AFP via Getty Images
A view of a toxic algae bloom on the shores of Guadeloupe. Credit: Loic Venance/AFP via Getty Images

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From our collaborating partner “Living on Earth,” public radio’s environmental news magazine, an interview with Bob Bewyn, a staff writer at Inside Climate News, based in Austria. 

Many of the effects of climate disruption are already in progress. One place getting hit especially hard is the ocean. 

According to the National Oceanic and Atmospheric Administration, the seas have absorbed more than 90 percent of the heat energy trapped by greenhouse gases since the start of the industrial age. And just like with IPCC scientists, marine scientists are overcome with grief and despair as their work suffers in the face of the climate crisis. 

Bob Berwyn, a reporter for Inside Climate News, has been on the ocean beat for more than a decade and has seen this eco-grief consistently throughout the course of his reporting. This interview has been edited for length and clarity. 

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AYNSLEY O’NEILL: What are some of the impacts that scientists have been observing?

BOB BERWYN: Going back a few years, there have been quite a few mass die-offs of all different types of marine organisms. The first time that they were really well documented goes back to 2003 in the Mediterranean, when ocean scientists there looked at what are called benthic organisms that live in shallow water in the seabed, mixed in with the sand and rocks—little snails and tiny crustaceans. They documented an almost complete disappearance of some of these species after just one single marine heat wave. 

Inside Climate News reporter Bob Berwyn
Inside Climate News reporter Bob Berwyn

Then if you fast forward a few years, we’ve had heatwave conditions in the Pacific Ocean that have resulted or contributed to die-offs of marine mammals, some of which have starved to death, because the extraordinary heat in the ocean made their food supply go somewhere else.

There was a starfish die-off that in some ways has been linked to very warm ocean conditions in the Pacific. There have been mass mortalities of seabirds there as well. Other impacts include things like toxic algae blooms that in turn also affect animals. There have been documented cases of fish and birds dying because they ate algae or crustaceans that had a toxic algae with them. The impacts are quite intense and quite widespread.

O’NEILL: With these ocean heat waves, I saw you quote a statistic from a climate scientist in New Zealand, and it was some pretty scary stuff. Can you tell me a bit more about that?

BERWYN: Fifteen years ago, people weren’t talking about marine heatwaves even that much because they only happened every once in a while and affected small areas. In the last 10 years, they’ve started to spread so far, become so big and last so long that it’s really hard for almost any ocean scientist to ignore them. 

Just a couple of weeks ago, the scientist Ben Noll in New Zealand calculated the extent of current marine heatwave conditions, and heatwave conditions extended across about a third of the world’s ocean, which is as if you had heat waves across North America, South America, Europe and Asia all at the same time—just huge, huge expanses.

O’NEILL: During your reporting, you spoke with a scientist named Jennifer Lavers who studies seabirds. What did she tell you?

BERWYN: She’s been studying around Western Australia, and has been studying seabird colonies for a few decades. She’s noticed that these ocean heat waves in the last years have really started affecting these seabird colonies. She was quite distraught about it. She said that sometimes, when she describes her work to people, she now feels like her research is documenting the extinction of the species that she studies, the flesh-footed shearwater. And it’s just one of many ocean species, birds and others, that are really being affected by these ocean heat waves.

O’NEILL: You’ve been on this beat for some time, covering the ocean. What have you seen in terms of the progression of ocean health, or perhaps lack thereof?

BERWYN: Many of the scientists—Jennifer isn’t the only one that I spoke with—have a real sense of grief and sadness, watching this incredible living system disintegrate in real time and is unseen to a lot of people, because it’s below the surface of the waters. 

It gets in the news when there’s a huge fish die-off, then there’s a day or two where you have front-page pictures on websites and newspapers if there’s a huge expanse of dead fish. This kind of stuff has gone on in the ocean all the time, just most of the time nobody sees it. There have been studies in the last couple of years warning that we’re headed in the direction of some of the greatest mass ocean extinctions known from the fossil record. 

Looking at fossils, we can tell, wow, at this time when the earth warmed really quickly 350 million years ago, more than 90 percent of all organisms in the ocean died. And we’re not at that point yet. But these studies are saying we are headed in that direction.

O’NEILL: In the northern hemisphere, summer is right around the corner. We’re keeping our eyes on the hurricane season that’s about to start in the tropical North Atlantic. And one of the key factors in hurricane formation is, of course, sea surface temperature. What have you been hearing about the consequences of ocean heat waves on these massive storms?

BERWYN: The part of the Atlantic that you’re talking about is also called by hurricane experts the main development region, that belt of the Atlantic between Africa and the Caribbean. 

What some hurricane scientists have been writing about and posting about on social media is that this area is as warm now as it usually is in mid-July, when the hurricane season really starts kicking into high gear. They’re pointing out that, combined with some other factors, this heat is a warning sign that the hurricane season could be very, very active this year. And there’s plenty of research from the last few years showing that the warmer the oceans are, the stronger the hurricanes can be, and that they pick up extra moisture, because the warmer atmosphere holds more moisture. 

When some of these storms come ashore, there have been climate attribution studies showing that certain hurricanes dropped a certain percentage more precipitation than they would have in a cooler climate. All told, this extreme warmth and long-lasting heat wave over that part of the Atlantic is a warning that we could be in for a really severe hurricane season. 

This part of the Atlantic has been at record warmth for months and months. At times, it calls into question whether a “heat wave” is really the right name anymore, because when you think of a heat wave on land, you think of an event that has a certain start date and an end date, right? Like, “Wow, last summer’s heat wave was a doozy, it lasted two weeks!” But these things in the ocean are going on for months. 

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O’NEILL: What was your takeaway from the scientists you spoke with here? What was the common sentiment?

BERWYN: I think they’re waving—and have been for a while—a huge red flag about the threat of global warming to marine life very, very broadly. And thus, the threat to people, because these are changes that potentially will threaten food supplies. 

Projections for the tropical oceans are that by the end of the century, they will be so warm that there will hardly be any fish at all in the world’s tropical oceans. There aren’t any fish that are adapted to the temperatures projected for the band of tropics just north and south of the equator. And evolution doesn’t happen that fast. It’s not like a new species of fish can evolve within seventy years to fill that ecological niche. You’re going to have millions of people living in tropical zones who are going to lose an important source of food. 

My main takeaway from talking to a lot of these scientists is that we need to stop global warming and hopefully slow the warming of the oceans, too, and slow this trend of more and more heat and more and more extreme heat in the oceans that is really damaging these ecosystems.

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