cares about himself. "nightline" is next. good night, everybody. tonight on "nightline" -- inside the melting arctic circle where the elusive polar bear is clawing for survival. >> the world should be interested. >> as their environment disappears beneath their feet, these powerful killers are moving inland toward human kind. >> is that the most frightened you've ever been in your life? >> yes. >> our amy robach on a to the edge of the earth. with the americans who call it home. >> most people have firearms just in case? >> and the scientists racing to save this vulnerable species. this special edition of

"nightline." vanishing ice. the last american polar bears will be right back.

>> this is a special edition of "nightline." vanishing ice. the last american polar bears. >> on the pure white ice they are almost invisible. an enduring symbol of the wild arctic. in reason years the polar bear

has come to embody something else. a creature caught in a changing world that is disappearing under its feet. there are less than 25,000 polar bears left in the wild, and few ever encounter them. but each year, dozens descend on this isolated alaskan village. we're going on a journey to the edge of the earth to understand what is pushing these elusive beasts closer to people. >> we are going to fly right over the arctic circle to barter island. hi! this is day three of travel. we have our fingers crossed because we're hopeful that we're going to get up there today to see the polar bears.

>> we'll check our latitude on the gps. they're extremely rugged as you'll see. an extremely remote area. >> so remote we lose contact with air traffic control. >> we have no communication. definitely a first for me but this is spectacular. how dicey can it get up here? >> you have to be confident. especially as remote as we are. >> even from this vantage point, our co-pilot says evidence of a warming plan set visible. >> the glaciers are receding. the fact things are getting warmer is undisputed in this climate. >> approaching bart he island, we get a preview on the stoney islands below. a white bear.

>> southwest barter island. the village of kaktovik, alaska, population, 239. a stark and striking landscape but not quite the snow blanketed mountains you might expect in the arctic. a change that has reached into all corners of life here. it's not long before we see what we came for. we left the shore three minutes ago. and already, there are four polar bears, right there, swimming in the water. that's incredible. what are we? 50 feet from them? we're pretty darn close. one, two, three, four polar bears. a mother with her triplets. these bears, a drab shade of brown. wearing the signs of spending so

much time on muddy land. >> wow! >> so they're playing with each other. >> our captain says these bears are here because they are waiting for the sea ice to return. the frozen surface of the arctic ocean where they spend most of the year feeding on seals. >> they know they have a long wait. >> until the freeze up, they scavenge on the remains of the whales the people must hunt to survive here. >> how long will the bears linger? >> they will hang out here until mid-november. and then when the ice starts forming out in the ocean, when that starts happening, the seals go on the ice. so the polar bears get their seals. on the ice. if that ice is not there, they don't get nothing.

>> the bears used to spend just three weeks on land. but today they are stranded for nearly three months because the ice is staying melted longer. scientists say it is due to global warming. in this part of the world, the sea ice is declining at the rate of 9% a decade. a dramatic number for polar bear conservationists. scientist dr. todd atwood tranquillize the bears, collecting samples. studying how climate change is affecting these bears. >> friction, i think. traction. those beautiful claws. >> we spend about 45 to 50 minutes with each bear that we capture. we collect a variety of samples, body measurements so we can see how physical stature might be changing through time. probably right on the cusp of being an adult. and we gave him seven cc's,

which is the standard dosage for a bear of this size. i think the most surprising thing for me personally has been the complexity of their behaviors. we've seen them department to some pretty dramatic changes in the ecosystem. we're seeing them use habitats to the extent that we didn't expect. we're seeing them switch to certain food items that we didn't expect them to switch to. we can see hair samples and relate it to how the environment has changed. to see if the changes are causing an increase in stress levels. currently, they are a vulnerable species meaning they have a high risk of endangerment in the wild. >> looking for polar bears is about learning to read the signs of their passing. here behind me are some very, very fresh bear tracks. >> in most places of the world, polar bears are incredibly

difficult to find. >> it was documented in the ghosts of the arctic. but in kaktovik, the sheer number of bears has sparked a tourist boom. >> what makes it worth it to me is simply seeing a beautiful white bear walking along the beach, who is basically here only because the ice hasn't frozen yet. ice that would have frozen years ago. >> here we are, unbelievably close to these bears. >> they're so cute. he's looking right at us. >> we're safe in the water. >> we're safe right here in the water. >> i'm glad i'm safely in this boat. >> on land it can be a different story, as bruce knows all too well. >> then this happened. i was stack beside him a good three seconds. >> and you didn't even know.

was that the most frightened you've ever been in your life? >> yes. >> i would think so. >> the opportunity to see them on land is too tempting. so as night falls, we set out in an suv. we are here right by what is called the bone pit. that's where whale carcasses have been left for years and years and years. and the polar bears come at dusk and feed on what's left of the bones. our guide tells us we can get a few shots but we have to be ready to make a quick escape. we were told we could get out of the vehicle as long as we heard him say get in and we run. no more, i need one more shot. he said you run straight back to the car. you don't know where they're coming from and they move very quickly so we would have to move

very quickly as well. though these bears are cute, they can be deadly. in 2013, a wildlife photographer captured the sheer power of a polar bear attack from inside a glass case. >> one of the most powerful animals on the planet. one of the most intimidating animals on the planett. one of the few animals. >> the males can weigh 1,500 pounds and stand order nine feet tall. they can charge at 25 miles an hour and their bite force is an astounding 1,200 pounds per square inch thoeflt all they need to kill. standing so close to these powerful creatures is awe-inspiring. but our guide says it is a bitter sweet opportunity. when i first came here, the packed ice was on shore all summer. now it is 150 miles away. >> and that has a huge impact on

the polar bears. >> that's why we have a lot here. this beautiful population the last ten years. we've been hunting whales about 10,000 years. they're coming because their habitat is gone. the world should be interested in this. >> while we're at the bone pile -- >> right there. >> we become concerned that they're interested in us. >> there's a mama polar bear with her two cubs walking not far from us. >> stay with us. when you're close to the people you love, does psoriasis ever get in the way of a touching moment? if you have moderate to severe psoriasis,

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is everyone looking? make the dream yours. no one's looking! in the remote alaskan tundra, a mother polar bears and her cubs are dangerously c c to us. mother bear seems the decide whale meat is a better dinner. as night falls, our guide, robert thompson, shows us evidence of a threat we may not be able to escape. signs that the climate is changing. >> melting. you see it over there. it's open. it melts more and the water flows out. >> years and years ago, the

fence was here and they said it wouldn't blow over. there are stakes in the ground. now they're melting and not holding the structure up anymore. >> it shows he the perma frost is melting. >> the coastline isn't permanent either. the coastline has chipped away at beaches, threatening towns and habitats. >> you love this land. how does it feel to see the changes are happening? >> well, i think the rest world should look at this and say, it will happen more to other people in other areas. marine life and marine animals, wildlife. >> dr. james wilder studies the polar bear population in the buford sea near barter island. he said these bears have been coming to these shores for thousands of years. but climate change has changed their behavior. >> polar bears are showing up earlier.

they used to show up in the beginning of september. now we see them in late july, august. and staying for longer. and that seems to be correlated with the availability of sea ice. if sea ice melts earlier, then bears will come to shore sooner. if it forms later in the fall, then they at the coast for longer periods of time. >> we're used to ice out there hunting. >> for the people of kaktovek, the way of life is at risk as well. >> this is the main road. >> she is a witness to the changes brought by rising temperatures. >> for all the tours. they're a nuisance. they can smell the good food anywhere. they had broken down our door to our cellar. >> for centuries, residents stored the whales they hunted in the permafrost. a natural underground freezer.

>> most of the ice filled up with water. and it is hard to keep them going. >> you used to have natural ice cellars. >> yeah. >> that have now melted? >> they washed out. erosion got all of them. their all gone. >> and now you have containers. relying on the earth is something they need to do. even though there's a grocery store here, that doesn't mean groceries are accessible for every one. $21. for a bottle of lotion. $34 for conditioner. it's tough. the prices are a lot higher. >> how challenging is it to keep your store stocked here on bart he island? >> the tourists, we're slowly getting it. >> it costs so much to get everything. >> yeah. my prices are crazy sometimes. >> another issue is safety.

while the locals know what to do about bears -- >> most people have firearms just in case? we try to do it. >> they don't understand that they're wild zmams their demeanor can change just like that. >> right. you all live among them. with them. you understand. >> kit get crazy when they start coming in. especially when they finish up there. they'll start coming into the town looking for scraps. >> they're hungry. >> it is such a problem there was a pole ever a bear patrol stepping streets. this bear going through the garbage. another peering into a window. >> i used to lock up the bar there. >> she told us how she locks the bears out at the end of her shift. >> that's why i do it.

>> so it's about 3:30 in the morning, i looked out my window and i saw them to check them out. a warning. >> this is the time of night the polar bears are out so we'll stay close to this door. it's unbelievable. i've seen pictures. i never thought i would see it in person. and there it is. in the sky. and it's surreal, actually. just as beautiful as i thought it would be. >> when we take off from batter island, we're he in awe of what we've seen. the fragility of this arctic world that may be melting away. from kaktovik, alaska. >> our thanks to amy and her

team for extraordinary

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and finally take a look at this incredible stunt. two dare devils jumping from a mountain about 13,000 feet up. then flying into the cabin of a plane in mid air over the swiss alps. the duo known as the soul flyers say they completed more than 100 practice flights in preparation for this stunt. thank you for watching abc news. as always, we're online at abc 7 news.com and on our "nightline" facebook page. thank you for watching and good night.

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