Scientists Study Changing Seas on Australian Island

On Heron Island, off the coast of Australia, weird moans of mutton birds surround scientists who have come to this outpost to study how global warming is changing life in surrounding seas.

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MELISSA BLOCK, host:

From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.

ROBERT SIEGEL, host:

And I'm Robert Siegel.

NPR is traveling the world this year, together with National Geographic, exploring Earth's changing climate. Today's installment of our series Climate Connections comes from Australia's Great Barrier Reef. It is the largest reef of its kind in the world, and it's a magnet for scientists. They go there to study 400 different kinds of coral, a thousands kinds of fish and platoons of birds. These days, the scientists are watching the effects of climate change.

NPR's Christopher Joyce has our story from Queensland.

CHRISTOPHER JOYCE: Near the southern tip of the Great Barrier Reef lies Heron Island. It's a few acres of sand and coral densely forested, and awash in the sound of tens of thousands of mutton birds.

(Soundbite of birds chirping)

Here and there, you'll also find biologists. Climate change has already warmed the ocean here, and scientists want to know what that means for life here.

Professor OVE HOEGH-GULDBERG (Marine Studies, University of Queensland): My name is Ove Hoegh-Guldberg. I'm the professor of marine studies at University of Queensland. And we're about to walk off the island onto the inter-tidal reef flat. Oh, sorry.

JOYCE: Professor Hoegh-Guldberg's right leg is knee-deep in what looks like a posthole.

Prof. HOEGH-GULDBERG: I hope I didn't hurt anybody by doing that.

JOYCE: Anybody would be a mutton bird. The birds dig nest holes in the sand. People tend to fall into them.

Prof. HOEGH-GULDBERG: One has to know where they're walking, break a shin.

JOYCE: Ove started coming here to Heron Island as a teenager. He grew up studying the reef and the exotic life it supports. Now an athletic 47-year-old with a diver's permanent tan, he is still here, on the lookout for change. Rising sea temperatures have already killed some coral. No one's sure what else is in store.

Prof. HOEGH-GULDBERG: A lot of us have been dragged away from what was initially just falling in love with the reef and all the beautiful creatures and so on. And now we're presented with problems and an urgency to solve them, because it's now the - our ecosystem, it's way of life and so on that might start to change rapidly.

JOYCE: Ove hikes down to the beach to look for two researchers out here somewhere, two women who sleep by day and roam the beach all night - as they are tonight - looking for turtles, greens and loggerheads and their eggs. The eggs incubate in the sand. But if a warming climate overheats the eggs, even a few degrees on average, well, sex on the beach won't be the same.

Ms. KATRINA IRELAND(ph) (Researcher): It'll skew the sex ratio, so you might end up - when it's hotter, there's more females. So if you have a lot of females running around and no males, you know, you're not going to continue the population.

JOYCE: That's Katrina Ireland, one of the turtle watchers. She calls this phenomenon, temperature-dependent sex determination. The gender of turtles is, in fact, just one thing that a warming climate could change. Ireland and her colleague, Tahia Isher(ph) are also investigating another weird possibility, that hot sand could create slower turtles.

Ms. TAHIA ISHER (Researcher): We're looking at how incubation temperature affects the locomotion performance. And I'm looking at the running abilities.

JOYCE: Running?

Ms. ISHER: Running. So, like…

JOYCE: I mean, you're telling me the turtles run?

Ms. ISHER: Yeah. They - when they run down the sand or they struggle, but…

JOYCE: I've never seen a turtle run. I'm sorry.

Ms. IRELAND: The little ones.

Ms. ISHER: Yeah, you know what I mean? Yeah, they just scramble down to the…

Ms. IRELAND: Obviously, the faster a turtle can run or swim out to the open ocean, the less chance he's going to be eaten by sharks, birds, fish.

JOYCE: Just about everything?

Ms. ISHER: Yeah.

Ms. IRELAND: Anything that's got a big enough mouth.

JOYCE: If turtles do make it across the sand, they've got the shallows to navigate. That's where we go looking for them now under a big, shiny moon.

Prof. HOEGH-GULDBERG: It's amazing how the sea at nighttime is like a puddle of silver.

JOYCE: Dark shapes hang in the water, winged stingrays and small shark.

Oh, that's a huge crab.

Prof. HOEGH-GULDBERG: I'll see if I can catch him.

JOYCE: Without getting bitten.

Prof. HOEGH-GULDBERG: I know. I'm going to take each claw.

JOYCE: Well done.

Prof. HOEGH-GULDBERG: I've got him - oh.

JOYCE: Oh, did he get you?

Prof. HOEGH-GULDBERG: He did. Oh, it hurts. Oh, well. I've learned my lesson.

JOYCE: And finally, a juvenile turtle, about as big as a dinner plate, pokes its head just above the waves, seemingly watching us make fools of ourselves. During the day, Ove takes us out to the reef flat. It's a shallow shelf made of ancient coral, extending out from the beach for hundreds of yards. The water's knee-deep and transparent. Underfoot, it's Ove's world.

It's that a rock with spots on it or is that something alive?

Prof. HOEGH-GULDBERG: A sea cucumber.

JOYCE: Oh, right.

Prof. HOEGH-GULDBERG: And they are fascinating animals.

JOYCE: Ove picks up something that looks like a fat slug the size of a salami. It squirts water out in one end.

Prof. HOEGH-GULDBERG: One thing it can do is that when a predator attacks it, it can cough up its entire digestive tract and sever that from its body and crawl away, while the predator is eating its digestive tract. And then, it can grow a new digestive tract.

JOYCE: Mercifully, this one keeps its guts to itself. Coral is an extraordinary collaboration. It harbors a tiny plant within its hard limestone skeleton. The plant traps sunlight and funnels it to the coral, so the coral can live and make more limestone skeleton. It's a lasting partnership. Some of the coral here a thousand years old. But now, it's threatened. In the last decade, warming seas have caused several widespread episodes of bleaching.

Prof. HOEGH-GULDBERG: Which is when the symbiosis between the coral and these tiny plants breaks up. And essentially, the coral kicks the algae out, these little plants, and in many cases, they die.

JOYCE: If the water warms even two degrees Celsius, coral can bleach and die. Scientists say the Pacific could warm that much in the next few decades. And there's something else going on - a lot of the carbon dioxide going into the atmosphere ends up in the oceans, and it actually changes the water chemistry, makes it more acidic. That makes it harder for coral to build the hard skeleton it lives in.

Recent scientific reports say the varied effects of climate change could severely damage the Great Barrier Reef in this century. That threatens the tourists' take from the Barrier Reef, about $4 billion a year. It's Australia's biggest natural tourist attraction. But Ove says there's much more than that at stake.

Prof. HOEGH-GULDBERG: Yes, people might get used to living without coral reefs. But then, do we really know what's around the corner? After all, this is all happening within the first degree of change. We might lose coral reefs. What happens next? I think people are waking up to the fact that it's not just about people that like coral reefs. It's about a very fundamental change to our children's future, as well as our own.

JOYCE: Scientists say what they're seeing here on Heron Island, coral bleaching, changing ocean chemistry, bird migrations that are out of kilter, they're all part of a much bigger phenomenon.

Prof. HOEGH-GULDBERG: It's about flooding in Tuvalu. It's about landslides in California. And it's about the loss of things like the Great Barrier Reef and kelp forests across Pacific. So it's all of these things connected. You know, this massive ecosystem is starting to move. And we have done it, this sort of rather simple primate from Africa, originally, is now sort of, you know, starting to tip an ocean.

JOYCE: Tipping into what? That's what worries scientists like Ove Hoegh-Guldberg. They don't know exactly what a warmer ocean will look like, only that it will be very different. People will adjust, as they have for millennia. How animals in the ocean will do, though, is less sure.

Prof. HOEGH-GULDBERG: Come and have a look at this. Where did it go? It's a epaulette shark. Oh, this is a strange, little, bottom-dwelling shark, which actually uses its legs as though it walks. Let me see if I can grab him.

JOYCE: Christopher Joyce, NPR News.

Prof. HOEGH-GULDBERG: I missed him again. I'm getting slow in my old age.

SIEGEL: You can find more stories about climate change at npr.org. And there, you can also see our cartoon series: It's All About Carbon, from NPR's Robert Krulwich and public television's Wild Chronicles.

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