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Photo of a polar bear (Ursus maritimus) and cubs in Churchill, Hudson Bay, Manitoba, Canada.

A polar bear watches over two cubs in Hudson Bay, near the town of Churchill, Manitoba.

Photograph by David Jenkins/Robert Harding/Corbis

Christy Ullrich Barcus

National Geographic

Published November 22, 2013

In the past month, hundreds of polar bears have strolled past a small town in Canada.

It's part of their annual migration back to Hudson Bay, where sea ice is reforming after months of summer melt. To get to the ice each autumn, they traverse Churchill, Manitoba—the "polar bear capital of the world."

These animals are the most studied group of polar bears on Earth. The renowned Ian Stirling, now retired from the Canadian Wildlife Service, began his groundbreaking research here 40 years ago.

Because this population comes ashore each year, says Steven Amstrup of Polar Bears International, they're relatively easy to count. "Searching for a white bear on green grass and brown rocks is easier than searching for [it] out on the white sea ice."

Churchill has only about 900 people, but several hotels. The polar bear migration is a huge tourist draw, as are regular sightings of beluga whales at the mouth of the Churchill River. Some 10,000 visitors flock here each year.

As the seasonal freeze approaches, polar bears gradually gather in the coastal areas around Cape Churchill. This gives people the chance to see them in the wild from the safety of giant tundra buggies, all-terrain vehicles that take tourists out from late October until late November.

While bear attacks in the town are uncommon—only a handful have occurred in the past 50 years—there have been three this year. To keep bears away from Churchill's center, residents honk their horns, sound sirens, and fire shotguns loaded with rubber bullets. The town also closed its dump recently, which had been a big draw for the bears.

Sea Ice: Home and Hunting Platform

Sea ice that forms annually is key to polar bear survival. It provides a vital platform to hunt ringed and bearded seals, which helps make Ursus maritimus the largest bear in the world and the top Arctic predator.

When the sea ice melts in the summer, polar bears make their way to land, where they save energy with what some have called a walking hibernation.

But today the Hudson Bay population—and the rest of the world's 20,000 to 25,000 polar bears—is being affected by changes. Since 1979, sea ice cover has declined by about 30 percent in the Arctic. As greenhouse gases continue to warm the Earth, Amstrup says, polar bears are being forced ashore for longer periods of time.

The bears of Hudson Bay, for instance, now spend an average of nearly 30 days longer on land than they did 30 years ago. Stirling and his colleague Andrew Derocher found that bears lose nearly two pounds of body weight each day they're on land—meaning the bears here are, in effect, 60 pounds lighter on average than they were three decades ago.

Stirling also found that lighter bears produce smaller cubs, which can struggle to survive. Since 1987, there has been a 22 percent decline in the Churchill polar bear population.

Because polar bears depend on a habitat "that literally melts as temperatures rise," Amstrup said, "they are perhaps the most vulnerable of any species to a warming world."

If nothing changes, he says, two-thirds of all polar bears will be gone by 2050—and perhaps extinct in the wild by the end of the century.

You Can't Go Home Again

According to fossil evidence, polar bears today look about the same as they did 120,000 years ago. At some point—perhaps during the frigid Pleistocene—they made the move from land to sea ice.

As the ice melts, some wonder if polar bears could readapt permanently to land. Amstrup says it's unlikely. And even if they could, it couldn't happen fast enough. "They can't undo hundreds of thousands of years of evolution in 50 or 100 years."

For one thing, there probably isn't enough suitable food on land for these huge animals—males weigh up to 1,200 pounds (544 kilograms), females 650 (205 kilograms). While goose eggs and a few other terrestrial food sources now supplement polar bear diets, there aren't enough of these to be sustainable.

A Collective Problem

Because polar bears depend so heavily on the sea ice, their plight is more visible than that of other species. But climate change is "really going to affect all life on Earth," says Amstrup.

He says a recent paper predicts "a sea-level rise of 2.3 meters (7.5 feet) for every degree of Celsius temperature rise."

"Because we could have two degrees Celsius in temperature rise by the middle of the century, that prediction is serious," Amstrup said. "Geologic records actually show that the last time the Earth was a degree warmer than it is now, the sea level was six to seven meters (20 to 23 feet) higher than it is now."

That could cause major coastal flooding—and vast displacement problems. Millions of people living near sea level around the world could be dramatically affected.

Economy and Ecology

Polar bear conservation faces a unique challenge. "The traditional model is that you set aside a reserve, or build a fence, to protect critical habitat," explains Amstrup. "But we can't really build a fence to protect the sea ice from rising temperatures."

The best way to ensure polar bear survival, he says, would be to curtail the rise of greenhouse gas emissions. Amstrup believes the only effective way to do that would be to charge a price, or a tax, for the carbon dioxide that humans are emitting.

"We're extracting fossil fuels, the primary productivity of the past, to subsidize our current economy," Amstrup said, "and we're expecting future generations to pay the price. When we utilize that ancient carbon, we should also pay that tax."

If policies required people to pay the "true costs" of using carbon, he says, it would "level the playing field, making renewable energy and other sustainable practices more competitive. The resulting competition would, in turn, stimulate our ingenuity, create jobs, and preserve a climate that will support polar bears and the rest of us."

Several European countries have already implemented carbon taxes. The United States, however, has not.

"It's not just an ecological problem," Amstrup said. It's "an economic problem. We have to remember that humans are not just observers of ecology; we're participants in it. Everything is connected. What we do in our economy directly influences the ecology of the earth."

The polar bear is an indicator species for the Arctic ecosystem. The challenges they're facing in Churchill today may one day be ours as well.

Do you think polar bears are important for the planet? Are you concerned about impacts to humans from climate change? What are your thoughts on paying a carbon tax?

Add your thoughts in the comments below.

Christy Ullrich Barcus is the editor of National Geographic's Polar Bear Watch.

Catherine Salki
Catherine Salki

An interesting and informative article, Ms Barcus. We are fortunate to have cognitive, credible researchers from organizations like Polar Bears International and the Churchill Northern Studies Centre (  Burying one's head in the [snow] and denying anthropogenic impacts makes one look and sound like a fool...snide, facetious comments are uncalled for herein and point to a lack of credibility on the part of at least one of the commentors below.  To them I say, back up your statements with peer-reviewed literature or be quiet!

Darrell Atkinson
Darrell Atkinson

I actually wanted to reply to Mitchell Taylor´s comment but due to lack of sound scientific knowledge about temperature changes I chickened out. If I read his report correctly he states that although the Earth has warmed up it is so minimal that we wouldn´t notice it.

The fact that virtually all glaciers worldwide are retreating at an alarming rate might seem to suggest that the difference does matter.

And so far no one has talked about Polar Bears being slowly poisoned by our by- products.( All those strange chemicals that evaporate from plastics for example and fall as a snow mix in concentrated form at the poles )

Maybe the complexity of the problem outweighs single peoples specialised knowledge however good it may be.

Mitchell Taylor
Mitchell Taylor

Articles like this make National Geographic seem like just another climate crisis propaganda machine, and maybe that is appropriate.  So Christy, here are the answers to your questions.  Some say that polar bears have been around about 160 thousand years and others say it could have been as long as 2 million.  Life have existed on earth for about 1.5 billion years, so maybe the planet could get along without polar bears?  Ever hear of evolution ... well it does not strive to create "important" species, and that includes you and me.  I'd hate to see them go, but that is not going to happen.

In the 133 years since the industrial revolution began global temperatures have increased only 0.74 degrees centigrade.  In recent times, the long-term average increase has been about 0.16 degrees centigrade per year.  If you were put into a room and it was cooled or warmed by the whole 133 year increment you probably couldn't tell if the temperature went up or down.  Plus there has been no trend in global temperature in the last 17 years.  CO2 has gone up (statistically significant trend) but global temperature has not (trend not significant at p< 0.235).  CO2 is a greenhouse gas, so there had to be a warming push ... but other factors that affect climate have prevailed ... no trend ... really ... check it out Christy!  Finally, ever wonder why the climate model projections never go past 2100?  Well it is because we are forecast to run out of natural gas and petroleum in about 35-40 years.  So the fossil fuel we have used to increase human doubling time from 1000 year to 41 years runs out.  Some think that might have an effect on world economies and even human carrying capacity ... but it will be good for the polar bears so who cares.

The sea ice decline you mention is not sea ice in all seasons; it is sea ice during open water season, and most of the loss has been in the arctic basin, not Churchill.  For the last 10 years sea ice in November, January, February, March, April and June (the main feeding months for polar bears) has not declined (no trend).  A recent aerial survey has shown no decline in polar bears in Western Hudson Bay.  The aerial survey actually showed a numerical increase in polar bears there.

Did you check anything?  Really perky article Christy, but just for fun ... next time shake things up by doing some actual research (beyond the Chief Scientist for Polar Bears International) and getting at least one thing right.

Answer to last question about carbon tax is "no thanks".  Even if there was a climate problem, and even if carbon tax would help, it is very clear that emerging economies around the world have not lost their minds and are more than ready to have a good economy and a middle class.  Here is a geography question ... Do you know what country will have the dominant economy by 2035?  Hint: It isn't the Euro block or the US.

Maybe think about a career in something you are better suited for ... like fiction.

Zara Ramaniah
Zara Ramaniah

I think that the Canadian government should be doing something to protect these majestic creatures. I don't understand why nothing is already in the works. Canada should be leading the way. 

Darrell Atkinson
Darrell Atkinson

Global Warming or not ??

A long time ago the Earth was almost universally Tropical. Then the various Fauna and Flora died off over a long period of time ( for us )

Now we´re releasing the CO2 from the once tropical world back into the atmosphere.

I´m not a Rocket Scientist and Computer models or not but it all seems quite clear to me why the Earth is starting to warm up ( again ! )

omar nasr
omar nasr

Why dont people understand that globle warming will not cause just other species to be extinct. But, it also might cause the extinction of us humans.

craig hill
craig hill

The carbon tax is not a serious proposal. Taxes are immensely easy to bottle up. The polar bear would be extinct by the time such a tax would be in force and collectible, and whether there could be connective tissue constructed between the tax and saving the polar bear, which currently at least is far-fetched. So that's a non-starter.  If the solution were thrown up to the minds of sympathetic problem solvers, wizards who live on the net, a solution might be forthcoming. It would have to take into account a food source on land for the polar bears, so they wouldn't be dependant on the vanishing ice from which to search for food fsr from land, and at the same time a maze of some sort to get to the food so that they use their muscles as polar bears must do. Otherwise, they'll be the first in a long line of extinctions that will leave humans collectively in despair, as we await our own disappearance. 

Harlan Colina
Harlan Colina

It's a good polar (bear) article. We all trying to understand what's really happening with our climate and also know the facts about what cause global warming its really important , but humans have been damaging the environment for centuries .Please not only pay attention to polar bears and the north pole  but to the entire planet, global warming is affecting  all the biomes of the world.  I love polar bears, i don't want then to go extinct, Neither big cats, elephants, sharks , birds, reptiles, insects , amphibians , plants , humans and much more. 

Jon LaDuca
Jon LaDuca

Is this how you make 7000 dollars a month from working at home?

James Syntax
James Syntax

Certain things are apparent...  The global warming theory is falling apart.  Just as the Global cooling theory fell apart in the 70's.   So now we just go with climate change so as to cover our positions.  The Polar bear:... let's see, it was smart enough to follow the food onto the ice, but can't figure out where to find it unless I stop using fossil fuel?  Turns out co2 is not nearly the problem we thought it would come to be...  You want alternative fuels... not a bad idea...   and if there's a tax involved you can bet government will like the idea too.  When will we learn you can't "mandate" behavior that is not logical.  We mandated fluorescent lighting... spent literally Billions... only to have "MAN" come up with better ideas...  we are still trying to give away Fluorescent bulbs....  people didn't want them, don't want them, won't use them, they serve no good purpose.... but now we have LED bulbs.... wow... brighter, instant light, and  more efficient (read Less fossil fuel used to power them")....  polar bears are a fond subject because we all want to see these magnificent animals survive...  But for some reason we don't believe they will find the food that will also move with the melting ice....    Now as to the claim: 2/3s gone by 2050... I'll put up the bet to anyone who wants to take it....  it won't happen.  The earth is a constantly changing environment.  The population of the earth is constantly evolving, moving, migrating, shifting...  When we ALL honestly begin to discuss our climate, I'll listen...  When those that fear warming step forward and admit, yes we cooked the books, ... when those who disagree step forward and admit yes, we ignore certain facts.... when it's no longer a reason to "Tax" .... I'll pay more attention.  This earth has been warmer in the past.  This earth has been colder in the past.  This earth will continue to change, and man has little to do with either movement.

Jim Steele
Jim Steele

Actually ringed seals studies show that less ice benefits them by allowing them to feed and fatten in more productive waters. There is always enough winter ice to breed on. During heavy ice years seal body condition worsens and that lowers the bears condition. Less ice has benefitted the whole food chain from plankton to cod to seals to bears. Read

Paul M.
Paul M.

What these lazy copy and paste news editors won't tell you:

* The polar bear was indigenous to as far south as Minnesota upon settlement but called the yellow bear because it retained its summer coat longer, but still the same bear.

*The climate change consensus was a 30 year old consensus of “maybe” and NEVER has science agreed or said any crisis WILL happen inevitably just "could be" a crisis for billions of children.

*Occupywallstreet now does not even mention CO2 in its list of demands because of the bank-funded and corporate run carbon trading stock markets ruled by trustworthy politicians taxing the air we breathe.

David Alan McPartland
David Alan McPartland

If the sea ice is gone wouldnt that mean the bearded seals and ringed seals would move to land to sleep and give birth as well ?  If both predator and prey moved onto land what would happen ? Is it a matter of the polar bear being too slow to catch the seal before it slid along the beach back into the sea? I mean the polar bear gets fat doing sneak attacks on these poor seals while they're denned up in the ice. Seals in sand dens or they would give birth in the open adding as advantage to the polar bear. Seems to me the polar bear could be just as successful if he aproached a colony of seals on a beach somewhere and went after the slowest or aging seals, much like other predators do. Losing the ice does not seem to me to be the polar bears ultimate demise. They are more adaptable (just like other Bears) than you think. Grizzlys bears are huge as well and very oppertunistic as far as eating whatever they happen accross. Polar bears will do the same if they have to.

Jim Steele
Jim Steele

@Darrell Atkinson Kilimanjaro has receded due to sublimation caused by lack of moisture and that is true for all the tropical glaciers. while some retreat may be due to warming, was not a function of temperature for those glaciers. The greatest rate of glacier retreat happened before the 1950s as we left the Little Ice Age. Glaciologist refer to the loss of glacial mass beginning in the 1850s as the Little Ice Age Paradox because temperatures had not warmed yet but glaciers were retreating. 

Jim Steele
Jim Steele

@Mitchell Taylor A welcome comment from a polar bear expert. I wrote a book with two chapters dedicated to exposing the polar bear propaganda and providing a ton of evidence supporting the Inuit claims that it is the time of the most polar bears. (some adapted essays were linked below) I have also quoted some of your studies. I would like to send you a copy in hopes that you might critique the polar bear chapters. If so please send your mailing address to landscapesandcycles [at]

And thanks for your efforts to bring scientific objectivity to the debate.

craig hill
craig hill

@James Syntax The ice is melting, blind bat. That's cuz it's whatchacall "warming". And yes, the Earth has been warmer in the past, but that was before polar bears. They fill a niche that's peculiar to 20th century weather, not 21st. By the time the climate "recovers" it'll be so hot we won't have oxygen for the lack of plants which can't live in such heat and for the lack of phytoplankton, which along with plants creates oxygen, which will disappear as well because of the acidity of the dead oceans for having absorbed all that carbon we're spewing constantly into the atmosphere.  If you live long enough, you'll see.  

craig hill
craig hill

@Paul M. You're a sucker for swallowing such propaganda from dirty energy profiteers. That the polar bear used to roam Minnesota is a clue to their shrinking presence under assault from a world where ice will not exist in enough quantity to keep them alive.

Miles Monroe
Miles Monroe

@David Alan McPartland  And your background in wildlife ecology is what, again?

The Koch brothers have your check ready anytime you want to drop by and pick it up ...

Jim Steele
Jim Steele

@craig hill @Jim Steele @Harlan Colina

Perhaps you should read the USGS report more carefully. They did emphasize  in the abstract that “Declines in mass and BCI [body condition] of sub-adult males, declines in growth of males and females, and declines in cub recruitment suggest that polar bears of the Southern Beaufort Sea have experienced a declining trend in nutritional status.”

However sub-adult males comprised a mere 5% of all measured bears. The abstract failed to mention that the body condition for 95% of all the other bears, both adult males and females, sub-adult females as well as all cubs, showed no signs of nutritional stress. In contrast, adult females represented about 34% of all captures, and despite being under the most stress due to an eight-month fast while giving birth and nursing their cubs, their body condition had improved.!

Improvement in the Hudson Bay was never published as reports always refer to the mid 90s but their condition is cyclic and the BCI improved since the late 90s. Researchers unpublished graph is linked here. I added the gray shading to highlight years when data was not considered reliable due to poor sampling.

Pepe Earthling
Pepe Earthling

@Miles Monroe It's good to know you're still a sceptic, Miles and that your mind isn't made up.


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