RACHEL MARTIN, HOST:
Scientists writing for the journal Nature have a new message. Their study calls on all nations to stick to the climate accord goals in order to help save the world's coral reefs. NPR's Rob Schmitz joins us now from the world's largest coral reef, the Great Barrier Reef in Australia. He's been talking to scientists there. Hey there, Rob.
ROB SCHMITZ, BYLINE: Good morning, Rachel.
MARTIN: What's the state of the barrier reef - the Great Barrier Reef? Scientists estimates that two-thirds of the northern section of the reef has died from bleaching in the past 18 months.
SCHMITZ: Yeah, it's pretty tragic. And, you know, I went out a couple days ago with a group of marine biologists who run tours of the reef. And I'm glad I had scientists with me because it's not really clear when you're snorkeling along the reef what's alive and what's dead. And the other problem for first-time visitors like me is that the abundance of fish and sea turtles and other wildlife is just so overwhelming that it's hard to assess the state of the coral.
In fact, after our first dive, I was sort of thinking to myself the coral I saw looked pretty healthy. It was really colorful, really bright. It kind of looked like "Finding Nemo" or something. But when I checked with John Edmondson, my marine biologist guide, after I got out of the water, he corrected me pretty quickly. And he said, this is a bad sign, not a good sign. And here's what he told me.
JOHN EDMONDSON: If the water temperature's just too high for the coral, then you start to see it getting stressed. The first appearance of that is when you start to see more bright colors, a lot more fluorescenty (ph) looking colors like really vivid blues, vivid mauves, vivid purples.
MARTIN: That's almost counterintuitive, right? So all the bright colors actually mean the reef is in trouble.
SCHMITZ: Right. Healthy coral's the color of like more subtler earth tones. But, you know, this flourishing of bright colors is actually an early sign that the coral is starving to death. And the next stage is when the coral turns bright white. That's known as bleaching.
And we saw a lot of coral that had been bleached and had just simply died from the rise in water temperature. And these were the conditions that scientists say have killed most of this section of the Great Barrier Reef over the past 18 months.
MARTIN: So you were talking with these scientists, spending time with them. How are they feeling? I mean, did you find any optimism there?
SCHMITZ: Well, I think many here are sort of in a state of shock. Losing two-thirds of the coral along this stretch of the reef is - in the matter of a year and a half is obviously terrible news for those who work here.
But, you know, despite that, one of the top scientists who studies the reef - Terry Hughes, who's also one of the main authors of that Nature article published yesterday - was surprisingly optimistic that the world's governments will continue to work toward that goal of keeping global warming under 2 degrees Celsius or 3.5 degrees Fahrenheit in the coming years. Here's what he said.
TERRY HUGHES: Our paper is actually, I think, more optimistic. And we look at the practicalities. What do we have to do to secure the future? Rather than just throwing up our arms and saying, it's all going to hell, what can we do to fix this problem? The elephant in the room for securing a future for reefs is dealing quickly with global warming.
MARTIN: And so then, Rob, but what are the chances for that if the U.S. pulls out of the Paris accord?
SCHMITZ: Well, exactly. On the face of it, that's not a good sign for the world's coral reefs that one of the largest carbon emitters has pulled out of an agreement to limit carbon emissions. I asked Hughes about that, and he had a contrarian view. He said Trump pulling the U.S. out of the Paris accord would largely be symbolic.
He pointed out that in the U.S., the states and individual cities have already done a lot of work when it comes to reducing their carbon footprints. And the markets are also playing a big role in addressing climate change. So he thought that future political changes in the U.S. leadership might also return the U.S. to rejoin the Paris accord someday. So he had a lot of hope that governments on whatever level will step up to save the world's coral reefs.
MARTIN: NPR's Rob Schmitz reporting from the Great Barrier Reef in Australia. Hey, Rob, thanks so much.
SCHMITZ: Thanks a lot, Rachel. Transcript provided by NPR, Copyright NPR.