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Planet in Peril

Aired April 24, 2008 - 23:00   ET


ANDERSON COOPER, HOST: For every action, there is an equal and opposite reaction. It's one of the fundamental laws of physics, of nature. Nothing occurs in a vacuum in the natural world. There are ripple effects and that is putting our planet in peril.

This journey around the globe is an investigation into the reasons our planet is changing. It's about the front lines, the places where threats aren't just forecasts of the future, but are happening now.

Where forests are lost.

JEFF CORWIN, WILDLIFE BIOLOGIST: We're destroying nature's natural regulator.

COOPER: Where islands are discovered.

UNIDENTIFIED MALE: This island exists because of global warming.

COOPER: Where water is poisoned.

DR. SANJAY GUPTA, CNN CHIEF MEDICAL CORRESPONDENT: A lot of people live around here and are dependent on this water.

COOPER: Where endangered animals are bought and sold and killed.

CORWIN: There's a lot of animals right here that range the gamut of critical status.

COOPER: Where people are dying.

GUPTA: We're hearing people are getting cancer from drinking water.

COOPER: This is a planet under assault. This is a "PLANET IN PERIL."

Tonight, we begin in a place that's warming faster than just about any other place on Earth -- Greenland's ice sheet. Right now in Greenland, it is eight degrees warmer than it was just about 10 years ago; eight degrees. Scientists say that is happening because of what we're putting into the air -- tons and tons of carbon dioxide.

The vast ice sheet of Greenland -- 1,500 miles long and more than a mile deep, the world's largest island; 80 percent of it covered by ice. It's springtime here, though nothing is green. This time of year the sun never sets -- it just dips down to rest on the horizon.

We're almost at the top of the world. But to really see what's happening here, you need to get on the ground. The ice is melting fast and this island is warming.

CORWIN: It's like nothing my eyes have ever experienced.

COOPER: It's all so surreal, I mean, if you look out at the horizon.

Biologist Jeff Corwin and I have come here to learn why and see what impact Greenland's melting ice sheet could have on all of us in the decades ahead.

DR. KONRAD STEFFEN, UNIVERSITY OF COLORADO: We have never seen a temperature rise in Greenland that drastic over a short period. It's only about eight years.

COOPER: So how far have we come?

STEFFEN: We actually drove 11 miles.

COOPER: Dr. Konrad Steffen of the University of Colorado has spent 17 seasons here, 300 miles north of the Arctic Circle.

What are these rotating things?

STEFFEN: We have several sensors at different levels. These small planes, they measure the wind velocity.

COOPER: He records the changing ice sheet through a network of monitoring and GPS stations. He's taking us to see and actually climb into a part of the landscape that's giving scientists important clues about why the ice is melting so fast.

The Earth's climate has changed much during the planet's history. There have been ice ages and long periods of warmer temperatures.

But scientists say our burning of fossil fuels like coal and oil has caused a greater concentration of heat-trapping greenhouse gases in our atmosphere. This buildup of gases prevents heat from escaping to space, acting like the panels of a greenhouse -- warming the entire planet. Arctic temperatures are rising faster than anywhere else on Earth.


As the atmosphere warms, the ice here melts and breaks apart, exposing water. That water absorbs the sun's heat and causes more ice to melt. Scientists call it a positive feedback loop, and it's causing Greenland's ice to disappear.

Last year, satellite data collected by NASA scientists revealed Greenland is losing 100 billion tons of ice each year. Ice does accumulate in the interior, but more ice is breaking off and melting at the edges. It's that imbalance which concerns scientists the most. If the entire ice sheet dissolved, sea levels would rise by 23 feet -- spurning a global catastrophe that would flood coastal cities and displace tens of millions of people.

Scientists don't think the entire ice sheet can melt any time soon, but every inch of sea level rise counts. Millions live near coastlines less than three feet above sea level.

You've been coming here since 1990?

STEFFEN: Well, we actually started in 1990. We came here not with the idea to monitor the abrupt change we currently observe. The first two or three years were actually colder than normal. But then '94, '95, it started to warm steadily. And since then, we actually have a temperature increase during the winter months of about four- and-a-half degrees centigrade, which is a very large temperature increase.

COOPER: Four-and-a-half degrees, that's enormous.

STEFFEN: That's one of the largest temperature increases we have on Earth.

COOPER (voice-over): Four-and-a-half degrees Celsius is eight degrees Fahrenheit. And here on the ice sheet, you can see the impact that temperature increase is having. It's creating rivers of melt water that carve deep holes in the ice called moulins (ph).

So this is a moulin (ph)?

STEFFEN: Yes, this is a moulin. You can see the water channel coming all the way down. Well, let's explore it further.

COOPER (voice-over): As more ice melts, more moulins appear. We gear up to rappel ourselves down inside. Hurling yourself backwards over a 1,500 foot cliff does take some practice.

CORWIN: It's easy. Just let yourself slide down, Anderson.

COOPER: Lean back.

CORWIN: Lean back and see it. And remember, if you want to brake, pull the rope up toward you.

COOPER: Climb back.


CORWIN: You've got to lean back. Step up. Step up. Step up. Excellent. Yes!

So now you feed the rope and it will just slide down like this.

COOPER: That was far more unpleasant than it needed to be.

So right now, obviously, there's snow here, but this could go much deeper.

STEFFEN: Yes. Usually these channels are up to 20, 30, 40 feet deep.

COOPER: So in the summer months ahead, as the temperature increases, water will actually start flowing through here?

STEFFEN: Oh, yes. Definitely. The water is so fast and has energy that actually carves into the ice before it drops into the moulin.

COOPER: Last year, Konnie and his team actually lowered a camera inside a moulin, capturing the first video from deep inside this icy tunnel.

And what is the big picture? What's the significance of a moulin?

STEFFEN: It actually is a conduit through the ice -- the ice sheet. And the water can reach the bottom of the ice. So once this moulin fills with water -- and water is heavier than ice -- it's possible that to lift up the ice. And then it's a lubricant beneath the ice. And that's when we see the ice moves faster.

CORWIN: So, basically, it's providing this layer of viscosity to the ice to slide on.

COOPER: So, because of the research you've been doing here, what is it that alarms you in terms of climate change?

STEFFEN: First of all, it got much warmer than we expected. So the melt season got much larger. If you look at the latest reports put together by all scientists that discuss the climate change, they estimate the sea level rise by 2100 to be about 50 centimeters -- one a-and-a-half foot.

If you take that number -- this is only based on melt. It's not based on the fast flow that generates additional icebergs. By 2100, we will be more likely one meter -- three feet -- instead of one-and- a-half feet.

COOPER: If the sea levels, by the models that we have now, are going to rise three feet in the next hundred years, can that be reversed at all?

Can that be lessened?

STEFFEN: Even if you reduce CO2 output at the current level and leave it level, the climate will continue to warm. So even by stopping the increase of CO2 today, we will have a warming. We will have a sea level increase.

COOPER: Climate change isn't just having an impact here in the interior of Greenland. You also see dramatic changes in the overall geography of the island, particularly on the coastal areas. We're going to travel to the east coast of Greenland, where a new island emerged has because of the retreat of ice.

UNIDENTIFIED MALE: That's it, right there.




COOPER: From Greenland's interior ice sheet, we travel to its east coast with Dennis Schmidt.

Do you expect to find other islands that were previously thought to be connected to the inland?

DENNIS SCHMIDT: Yes. There will be others. In fact, we know where they are. We're looking for...

COOPER: Schmidt is a modern-day explorer. San Francisco is his home base, but Greenland is more like home.

SCHMIDT: This is a peninsula -- it's an isthmus connected to the mainland because of an ice shell.

COOPER: He's been coming here for more than 40 years. His explorations have led to discovery.

SCHMIDT: Yes, OK. We're flying right over it now. We're just on top of it.

COOPER: I joined him to see his latest -- one of the starkest examples of climate change. It's not easy to land on a glacier, especially one jutting out from a steep mountain. Our pilots make several passes scouting for a safe place. The co-pilot jumps out to test the snow pack. Finally, we put down. We are the first people to ever visit here.

SCHMIDT: No one has ever been here before. We're the first people ever to walk here.

COOPER: No one has ever been here? Really?

SCHMIDT: No, we're the first to ever walk here.

COOPER: We're here to see something extraordinary -- Greenland's retreating ice has revealed a new island.

In 2005, you came here. You were on a ship...


COOPER: When did you realize, wait a minute, this is an island, this is not part of the mainland?

SCHMIDT: Yes. I sailed into the peninsula. As we sailed into the base of it and we kept finding open water, I became disoriented. That was the beginning of the movement of discovery, where I realized something was wrong.

Either I was in a different place or the place where I was had completely changed. And I pointed to the area of open water at the edge of the face of the glacier and I said that's the world's newest island.

COOPER: The world's newest island, discovered because of the world's warming temperature.

So is this island an example of global warming?

SCHMIDT: This island exists because of global warming. This is a peninsula that became an island because the ice fields that connected it to the mainland of Greenland melted and structurally destabilized and broke away. So without the climate change, this would still be a peninsula.

COOPER: You have to be very careful when you're walking on a sheet of ice or a glacier in Greenland because there can be hidden crevices that open up. You could fall right through, and that will be the end of you.

The thickness of the ice in Greenland has been changing over the last few decades. It's of great concern to scientists who are studying it. They found that in some spots, ice thickness has diminished by as much as 40 percent in the last 40 years.

SCHMIDT: That's what you want to look at now. We want to study this.

COOPER: When you discover an island here, pending approval, you get to name it. Dennis chose the name Warming Island.

That's a glacier over there and these two glaciers used to be connected by an ice shell?

SCHMIDT: They were continuous, yes.

COOPER: Even the map of Greenland is changing. After two days exploring with Dennis Schmidt, we head back to the interior and Dr. Konrad Steffen.

STEFFEN: Hey. Hi, Anderson.

COOPER: Does it surprise you that new islands are cropping up in Greenland?

STEFFEN: No, I would not be surprised because we know the ice is retreating.

COOPER: Dr. Steffen and his team live in a research station called Swiss Camp. They spend one month every year here, living under extremely difficult circumstances. You have to see it to believe it.

So this is where you sleep?

STEFFEN: First, we slept in the station at the beginning.

COOPER: Right.

STEFFEN: But during the cold years, we had some water that froze in the middle tent, which was our sleep tent, which was not very comfortable. So we decided we would go out and put our tents outside.

COOPER: In case you're wondering, there is a bathroom. Out here it's an igloo. They call it the shigloo. The cold hasn't snapped their sense of humor.

What are these three -- these are tents?

STEFFEN: Yes. This is actually Swiss Camp. This is our office where we have the electronics and computers. We also have a refrigerator. We actually stand in our refrigerator.

COOPER: Oh, nice. This is your refrigerator?


COOPER: Really?

STEFFEN: But it's filled with some fish and some steaks.

COOPER: That sounds good.

So we go down a ladder here?


COOPER: All right.

STEFFEN: Be careful. It is rather steep.

Hi, Terrie.

UNIDENTIFIED MALE: How are you doing, Konnie?

STEFFEN: Good. Do you have some coffee?

UNIDENTIFIED MALE: No. It's not ready.

COOPER: The makeshift kitchen where the dinner table doubles as a work space. Primitive, but they figured out how to keep the bread maker working.

STEFFEN: We have fresh bread every day. Watch your head here. Then we can go over to the work tent. This is our work center, as we call it, the computing room.

COOPER: In this small, cold space, Dr. Steffen and other scientists analyze the data they gather on the ice sheet. A stark finding that for Dr. Steffen raises a very basic question. STEFFEN: The question is how can we actually change it for the future? We should not just think for ourselves. We should think for the next two, three generations.

COOPER: As Dr. Steffen pointed out, climate change is something that's going to be affecting future generations. But it's also something that's having a major impact on people and animals right now.

Jeff Corwin's gone to track North America's largest carnivore, the polar bear -- to find out what some scientists believe the polar bear's very existence is under threat.

CORWIN: Searching for polar bears in Northeastern Alaska isn't like looking for a needle in a haystack; it's like looking for a haystack-colored needle in a haystack.

We have this incredible terrain of ice that seems to almost go on forever. Somewhere hidden on this ice, on this white-reflected snow and ice, is a white creature that we need to catch up with.

Steve Amstrup, a wildlife biologist with the U.S. Geological Survey, has been doing this for 26 years, trying to learn all he can about what polar bears can tell us about global warming.

STEVE AMSTRUP, U.S. GEOLOGICAL SURVEY: There's a nice lead here that we might be able to pick up footprints on.

CORWIN: His eyes are keenly trained to find what seems impossible.

AMSTRUP: OK, you see tracks going across that hill (INAUDIBLE)?

CORWIN: Oh, my goodness, look at that.

UNIDENTIFIED MALE: There's one big set of tracks and two smaller sets.

UNIDENTIFIED MALE: We've got a family group.


CORWIN: However, finding the tracks is only the beginning.

AMSTRUP: Boy, they did a 180-degree turn here.

UNIDENTIFIED MALE: She's now at 12 o'clock, doc, right off the nose.

CORWIN: Our helicopter hugs the ground as we trace the footprints through the snowy expanse over the rubbled ice, until finally we spot them.

UNIDENTIFIED MALE: Hey, I see the tracks are going along there. That's a long...

UNIDENTIFIED MALE: And there's a bear right there.

UNIDENTIFIED MALE: Oh, look at that!

CORWIN: This is what it's all about right here. We have this sow and she's got some cubs alongside. And now we're going to move in. And you're about to see something absolutely incredible.

SCHMIDT: Boy. Good deal. Yes, straight across. OK. It looks good. We're right on them.

CORWIN: Amstrup loads the tranquilizer dart into the gun as we circle low over the mother bear to make sure we don't scare her away from her cubs. Then we lift up and she takes off, racing across the ice. Our helicopter lowers down within feet of her. And Amstrup, hanging from the side of his window, aims and takes his shot.




CORWIN: We are on the heels of a mother polar bear and her two cubs. U.S. Geological Survey scientist Steve Amstrup loads his tranquilizer gun. Our helicopter lowers just over the running sow. Amstrup aims and then fires the dart.

UNIDENTIFIED MALE: Did you get it?

AMSTRUP: The top of the shoulder. The top of the shoulder. OK, now let's get the bears back together.

CORWIN: So here's the plan. Steve got a beautiful shot; he landed that anesthetic dart right in the shoulder about a minute ago. We need to give us some time to drop (INAUDIBLE) rather quickly.

Of course, we don't want mom and the cubs to separate. So once we're above them, we'll get down and we'll actually physically capture these cubs, anesthetize them and gather data.

That data is part of Amstrup's annual field study. He's exploring how a warming planet is impacting the polar bear. And what he's discovered is startling.

Armed with a pistol just in case, Amstrup and I moved in to secure the cubs.

AMSTRUP: Put the noose there. I will grab it. OK.

CORWIN: With the bears safely sedated, Amstrup gets to work.

AMSTRUP: This is a female cub. Polar bears are probably the most important symbol of the Arctic from the standpoint of a measure of the health of the Arctic ecosystem because they are entirely dependent on the surface of the sea ice for catching all of their food. And the food that they eat, the seals and other marine mammals, are entirely dependent on the ecosystem below them.

So as the apex or top predator in the ecosystem, polar bears sort of integrate everything that's going on in the ecosystem underneath them. 56 even.

CORWIN: Amstrup has been studying the polar bear for the past three decades.


CORWIN: His data indicates an animal that's changing along with the habitat around it.

AMSTRUP: We are starting to see some changes that may result in future concerns for this population. We have seen declines in the survival of cubs and we have seen adult males and cubs a little bit smaller in recent years than they used to be. And those are things that would be consistent with the population that might be under nutritional stress.

CORWIN: Under nutritional stress because it's simply getting harder for bears to eat.

It's an impressive opening in the ice here. This is a lead. And of course as you can see, of course, we are not alone.

A polar bear's primary source of prey are seals. They have the most success hunting seals in a 20 to 50-mile gap of water between coastline and ice. The water is more shallow there and the seals are more plentiful. The problem is, though, just like in Greenland, that ice is melting.

AMSTRUP: When the ice melts in the summer, it used to be that it only withdrew from the Alaska coast a little ways; maybe 10, 15 miles, sometimes a little farther than that. In recent years, we had a gap of sometimes as much as 200 miles north of the Alaska coast.

CORWIN: As a result, biologists are now witnessing some very strange bear behavior. Some of these animals are actually drowning, trying to swim these new open waters. Now, remember, these are marine mammals, so they are not supposed to drown. There are even cases of polar bears cannibalizing each other when the food runs short.

AMSTRUP: Ultimately, they are all dependent on the sea ice. And if the sea ice continues to decline as it has, it's going to affect polar bears.

CORWIN: The sea ice is melting, melting faster than anyone expected. University of Colorado researchers say that in 2007, the Arctic Ocean lost one million square miles of sea ice. That's roughly six times the size of the state of California.

It is a record rate of decline. Sea ice loss has now surpassed predictions for the year 2050. If the melt continues, Amstrup now thinks two-third of the world's polar bears will be gone in 50 years. It's those types of numbers that have led to an unprecedented move. The Bush administration is proposing adding the polar bear to the endangered species list.

It's a global population of polar bears is somewhere between 20, 25,000 animals, why are we today trying to enlist them as an endangered species?

AMSTRUP: The purpose of the proposal that the Fish and Wildlife Service has is not to lift bears because of their present status, because of their present population, but because of their anticipated future status if the sea ice continues to change the way climate models project that it is likely to change.

CORWIN: It would be the first time an animal has been protected because of global warming. It might be the only way to save an animal that, along with its habitat, could simply disappear.

To know that this charismatic, incredible life form could very well become extinct because its habitat is warming up and the ice it needs to survive is disappearing is really most profound.

The thing is, we've also learned that climate change is impacting total environments as well as the ice sheet on top of Greenland is very quickly melting way. But above and beyond that, beyond the environment, beyond the impact on wildlife, human beings can be negatively impacted from climate change.

To truly understand that, we are now going to travel with Dr. Sanjay Gupta, as he experienced how climate change is impacting people today in the South Pacific.

GUPTA: We have been trying to get here for a few days now. It actually took five flights leaving from southern China.

They say that the water is actually going to cover this entire island within a few years. What's going to happen to you?



ERICA HILL, HEADLINE NEWS BULLETIN: I'm Erica Hill. Back to Anderson and "Planet in Peril" in just a moment. But first, the headlines.

The White House today breaking its silence on a Syrian nuclear facility that Israeli bombers destroyed seven months ago, saying it was built with North Korean help and releasing photographs of that plant up close. There's no word though on who took the snapshots.

The CIA briefer showed Congress today the pictures show the plant from the outside. Inside, briefers say the reactor core is nearly identical in layout to North Korea's reactor in Yongbyon. Now, what's more, those photos include a shot purportedly of a top North Korean nuclear official with a Syrian counterpart at the plant. Israeli jets destroyed the facility reportedly within weeks of it going operational.

No breakthroughs today from President Bush's White House meeting with the Palestinian president, Mahmoud Abbas. Mr. Bush did say he's working hard to help the party hammer out a peace deal at establishing permanent Palestinian states.


GEORGE W. BUSH, PRESIDENT OF THE UNITED STATES: A viable state, a state that doesn't look like Swiss cheese; a state that provides hope. I believe it's in Israel's interests and the Palestinian people's interest. They have leaders willing to work toward the achievement of that state.


HILL: John McCain today in New Orleans touring the lower ninth ward slammed the Bush administration's response to Katrina.


SEN. JOHN MCCAIN, (R) PRESIDENTIAL CANDIDATE: America will never forget, I will never forget, and never again will there be a mismanaged natural disaster, man-made or natural again that will occur in this country.


HILL: Hillary Clinton today campaigning in North Carolina where, unlike Pennsylvania, Barack Obama is heavily favored. He took the day off from the trail.

In Texas, bus loads today carrying children of the FLDS sect connected to Warren Jeffs in that polygamist compound in Texas, taking these children to foster kids. The number of kids revised upward, when 25 mothers were found to be under 18.

And Kansas City, talk about a remarkable rescue. Four construction workers pulled from a flood control tunnel after their boat capsized in high waters. All four workers are reported to be in good shape.

That's a quick look at your headlines. Back to "Planet in Peril" after this short break.



GUPTA: Flying over the Solomon Sea in the South Pacific, the ocean and the sky melt together in a blue-green haze. We are 60 miles from any land, only open waters in every direction.

On the horizon, a small cluster of islands rise up from the sea, a long coral reef wrapping around them. These are the Carteret Islands of Papua New Guinea, one of the most remote places on earth. We have been trying to get here for a few days now. It actually took five flights leaving from southern China in a helicopter ride, which you just saw.

We have come here to meet the people of Carteret. The reason that we're here is because we hear that this island is sinking. And it's unclear exactly why. Some people say it's climate change. Some people say its damage to the coral. Some say it's just sinking naturally because it was built on a volcano.

Over the next few days, we're going to figure out why and report that back to you.

The five islands that make up the Carterets are just five feet above sea level at their highest point. The shoreline is steadily receding. Trees that once stood on the beach are now submerged.

If the islands were uninhabited, it would simply be another mystery in the natural world. Instead, tragically, 2,000 people live here, and they are literally being washed away.

This was their garden. The rising seas have washed it out. It's now a mosquito-infested swamp. The swarms have brought with them malaria. It's now the number one killer here.

Do you feel like the people here have been forgotten?

ROSE: They have been, definitely.

GUPTA: Rose has lived on the island with her family for 12 years. She says life here used to be good. Now unable to grow their own food, they are dependent on supplies from the government of Papua New Guinea that come twice a year by boat from another island 60 miles away, just twice a year.

ROSE: The supply that we have from the government, which is how many bails of rice, it's already finished. And we are living on coconuts. Plus if we have fish from the sea, then we have fish. If we don't, we can live one day without food or two days without food.

GUPTA: That sounds pretty scary. It sounds like people are going to go very hungry, if not starve.

ROSE: Yeah, I think so.

GUPTA: It looks like this upsets you?

ROSE: It does, it does. It is even very hard.

GUPTA: The people of the Carterets call themselves some of the world's first climate change refugees. What's happening here is a sobering glimpse into what scientist says the future will look like even if modest sea level rise predictions prove true.

Tens of millions of people will have to be relocated. That's exactly what's happening to the people of the Carterets. They are moving to yet another island.

But many don't want to go, and it's easy to see why. The island of Bougainville is a dangerous place. It suffered through a ten-year bloody civil war during the 1990s. Schools were closed for a decade. Thousands were killed. Crime and unemployment are high. The unrest and scars, still visible today.

So for now, the people of the Carterets are left to wait and fight against the rising tides. But is climate change really responsible for what's washing away their world?

Like the earth's climate, the world's oceans have also warmed one degree Fahrenheit. When water heats up, it expands and rises. Scientists call it thermal expansion. Global sea levels rose about 1.8 millimeters a year in the 20th century. But since 1993, an even higher sea level trend of 3.1 millimeters a year has been recorded.

While difficult to measure exactly how much, scientists believe part of the rise is due to melting glaciers and ice sheets, like the ones we saw in Greenland. That melt is picking up steam, raising concerns for even more sea level rise, putting the Carteret Islands and others like it in further jeopardy.

You can see some of the trees here. I mean these actual trees, look what happened. Did the water just knock them down?

BERNARD TUNIM: The water just knocked them down. And maybe in two, three years, this whole area will be just completely washed out.

GUPTA: I met with one of the island's chiefs, Bernard Tunim (ph). He was born here, as were his parents and grandparents. He worries that he may no be able to stay much longer. Why is it happening?

TUNIM: Now because of the understanding of global warming, we believe that what is melting in the Arctic or the place where there's ice. And when that melts, the water is affecting us because the level of the sea is rising all of the time.

GUPTA: But it might not be that simple. What we saw from above the islands was a coral reef that appeared bleached and dying. Reefs serve as natural barriers to heavy storm surges that can swamp low- lying lands.

So is it rising seas or the loss of coral that's causing the Carterets to sink? When we come back, our investigation continues beneath the surface.




GUPTA: We're flying back to the Carteret Islands in the South Pacific to try and solve the mystery, why the islands here are disappearing. Is it rising sea levels or something else entirely?

After two days here, there was only one place left to explore, underwater. Chief Bernard (ph) takes us out by boat to the coral reef. He tells us we're the first journalists to dive the reef.

With dive gear and tanks, we head down 60 feet. What we see is startling, a gray landscape with little marine life. Healthy coral reefs act as protective barriers to islands, helping slow destructive storm surges while providing food and shelter for marine life. This reef is dying, which means less protection from storms and fewer fish to eat.

So from the air, we can look down at the coral, it certainly looked like a lot of it was dead. We actually just dove down. And when we got down there, we saw evidence of what seemed to be bleaching. We actually saw entire sheets of coral that seemed to be completely dead and washed out. Now, there was some evidence of live coral, but it was interesting that some of that appeared to be dying in the process as well.

Coral bleaching, scientists say, is a result of global warming and it's happening in oceans around the world. Increased temperature and light cause the coral to expel the algae cells that live in their tissues. When the algae leaves, coral takes on the bleach coloring. Many coral reefs often die after bleaching.

And that, it seems, is what's happening to the Carterets. Global warming might be causing a slight rise in sea levels, but its larger effect here is damage to the coral reefs that protects these islands.

Combine that with the fact that Carterets sit on top of an ancient volcano, that over time collapses inward and they could be sinking naturally as well.

But none of those reasons mean very much to Rose. Her home is disappearing. Her future is at best uncertain.

I can see the water from here, Rose, and they say that the water is actually going to cover this entire island within a few years. What's going to happen to you?

ROSE: I will have to stay.

GUPTA: But it's sinking.

ROSE: No, it is definitely sinking but the life here is too valuable to leave.

GUPTA: We're going to take you next from a place that suffers not from too much water, but from not enough, Lake Chad. It used to be one of the largest lakes in the world, but it's disappearing.

It was once the sixth largest lake in the world, covering more than 10,000 square miles. But over the past 40 years, Lake Chad in Central Africa has shrunk by 90 percent. Where there was water, now only sand. UNIDENTIFIED MALE: Here we are suffering. We are suffering from the climate change. It's obvious here. We are fighting for survival.

GUPTA: We're here because we are told this is one of the most concrete examples of climate change anywhere in the world. People are dependent on their water and they are not getting enough. Less water also means fewer and smaller fish and as a result, the people are getting smaller as well.

But the water crisis may be more than just climate change. We wondered, did something happen to the once-mighty river that feeds Lake Chad? We decided to go there and try to get some answers along the way. Lake Chad borders four different countries - Chad, Cameroon, Nigeria, and Niger.

UNIDENTIFIED MALE: Up to this wall --

GUPTA: Our guide is Anada Tiega (ph). He's a native of Niger. He has seen the dramatic changes firsthand.

ANADA TIEGA: The struggle today is how to get food. People do not have enough food. Even if they had enough food in terms of quantity, the quality is decreasing. And the diet of people is becoming less balanced.

GUPTA: As the wetlands manager, he spent the last four years working with the Lake Chad Basin Commission, a group that's trying to save the lake.

There are roughly 37 million people who rely on Lake Chad. And they are quickly depleting what water is left. Much of it is siphoned off to irrigate crops.

The lake has dried up before. Natural changes in the earth's orbit and the tilt of the sun 10,000 years ago caused the climate to shift, bringing out a long drought.

But that's not what is happening today. The consensus among scientists is something is different. From the air, it's clear the lake is dropping. And this is what it looks like here on the ground; sand all around me. Look at this dry, cracked, parched earth.

The water here used to be at least six feet high and now all around me, there's nothing. I'm standing in Nigeria, what used to be the middle of Lake Chad. Believe it or not, this is the rainy season.

And that, scientists say, is a direct result of climate change. As the earth gets warmer, moisture in the atmosphere that used to fall as rain instead evaporates. Water held in the soil and in lakes is also disappearing.

It's clear the weather patterns here have changed. The summer rains no longer able to replenish the lake so many people have come to depend upon. Climate change is making a bad situation worse.

Ironically, Africa is the lowest carbon emitter in the world. Yet due to its dry climate, scientists say it's the most vulnerable to the effects of climate change. Combine that with the fact that Africa's population is growing faster than anywhere else in the world. The pressure on dwindling resources becomes clear.

We press on. And after two long days of driving in the sand, we are closing in on the source of Lake Chad and hopefully to the answer as to why exactly it's disappearing.

It's 114 degrees in the desert when things take a turn for the worse. When we come back -- trying to break free from Africa's sinking sand.

We are stranded. We are stranded as it turns out right now.



COOPER: Coming up tomorrow night on "PLANET IN PERIL," Sanjay's investigation into why Lake Chad is disappearing continues.

We'll talk to some of the world's leading scientists about the myth and realities of climate change.

And Jeff Corwin and I go into the Amazon jungle with an anti- poaching taskforce bent on stopping the destruction of a place that holds one-quarter of the world's species.