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Polar Bear Research

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How important is the link between polar bears and sea ice? USGS Associate Director for Biology Sue Haseltine talks about it, along with some other aspects of the USGS's recent polar bear research.




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Welcome back everyone, and thanks for listening to the USGS CoreCast. I'm Scott Horvath.

Today we have a very exciting topic to talk about . . . not that all of our podcasts aren't exciting, of course . . . but today in particular is a very hot topic right now in the news: That's polar bears.

I'm sitting here right now with Sue Haseltine. Sue is the Associate Director of Biology for the USGS, and she's excited to sit down and talk with us about the recent USGS polar research and what that research exactly means.

For those of you that don't know what this about, here's a little bit of background on this topic. In January 2007, the U.S. Fish and Wildlife Service proposed listing the polar bear as a threatened species under the Endangered Species Act.

To ensure that the best information was available to inform the final listing decision, which is due in January 2008, the Secretary of the Interior, Dirk Kempthorne, asked the USGS to analyze existing information and generate new scientific data, models, and interpretations on polar bears and their sea ice habitats, and then make them available within the decision-making time frame. So, today Sue is here to help break down those results in a way that us non-scientists can understand better.

But before we get to that, I just thought I would share a few interesting and educational did-you-know tidbits about polar bears. I thought these were kind of cool, so I wanted to pass them on to you.

The scientific name for polar bears is "ursus maritimus," which actually means "maritime bear" or "sea bear," and their optimal habit is in on the sea ice, especially over the continental shelf, around the Arctic region.

They can grow up to 8 feet long and weigh up to 1,700 pounds—even the smallest adult polar bear can weigh in over 600 pounds. . . not exactly the type of animal you want to make upset . . . you won't be running very fast if you're on a sheet of ice, I'm sure.

Although they appear white in color, a polar bear's skin is actually black (which is what help keeps them warm) and their fur is actually clear because it lacks pigment. The reason they appear white, though, is because the light is being refracted off their clear hair strands. Their hairs are also hollow tubes, where the air inside of them helps them to stay afloat.

Polar bears can also endure extreme cold because they have 2 to 4 inches of blubber layering their bodies. And their thick undercoat actually makes them nearly invisible to infrared photography . . . and only their breath and muzzles can be easily seen.

Lastly, polar bears are able to swim up to 40 miles in a single stretch and can run up to 25 miles per hour. Wow, that's fast.

So, now that you have a few bits of polar bear knowledge, let's talk with Sue about the USGS polar bear research results. Sue, thanks for joining us.


Thank you, Scott.


So, what prompted this research exactly and how was it conducted?


Well, as you said, the Fish and Wildlife Service proposed listing the polar bear as endangered throughout its whole range, which is all of the Arctic region. It's a circumpolar species. So, we have done a fair amount of research in this country on the part of the polar bear range that we have off of Alaska, and we share the polar bears, since it's a very mobile species, with 600 other countries around the world. So, we have very spotty knowledge [Scott: laughing] on the polar bear and the Secretary asked us to accumulate all that knowledge and synthesize it for the Fish and Wildlife Service.

We also have been working with several agencies to do sea ice observations over the last 20 years or so. And he asked us to look at sea ice as the habitat for polar bears, and it turns out all sea ice is not created equal [Scott: laughing].

So we were asked to characterize the habitat of polar bears. Then, finally, we were asked to project both sea ice and polar bears into the future to give the Fish and Wildlife Service some context for their decision. They had determined a 45-year timeframe to look at whether polar bears were increasing or decreasing in the Arctic. So we we're asked to project polar bears out that far. [Scott: Wow.]

So to do this, actually we had a team of USGS scientists, but we also interacted with many other experts around the country. We had experts from Woods Hole, from the University of Wisconsin, University of Alaska, from the Forest Service. So we really assembled a very credible team of scientists who look at this issue and try to relate this all together.

The other caveat was the Fish and Wildlife Service has to make their decision by January, so the Secretary asked us do all of this synthesizing of information as well as collect any new information we could and model into the future. He asked us at the end of January, and we had to have our work done by the end of September. So there was a very short timeframe, so we had to determine what we could get done in that time frame.


[Laughing] Yeah, that is kind of short. Great. OK, so what about the polar bear populations and the habitat did the USGS examine?


Well, actually we looked at sea ice around the Arctic and we did several things. We, first of all, looked at the global circulation models for climate change, and we looked at which ones predicted, at least from over our observed records, sea ice most closely.

There's some of the global circulation models that actually say the Arctic is ice free and there's some that say we're not getting much melting in the summer. So, we picked those that most closely mirrored what we are observing in the sea ice, and then we defined, with the help of our colleagues around the Arctic, optimal polar bear habitat. So, as I said before, not all sea ice is the same. And we looked at how that habitat would change over time.

Then finally, polar bear specialists divide populations into 19 management units, or sub populations [Scott: That's a lot.] and we only had good information on four of those. So what we did was try to use those as models and predict the results we have about how polar bears are responding to sea ice in those smaller areas over a larger area of the Arctic in order to do predictions, or probability estimates . . . how much polar habitats and polar bears would be there in the future.

So, it was a very complex process [Scott: sounds like it], and we tried to bring all of these things together. Finally, in the end one of our lead polar bear biologists from the Alaska Science Center, Steve Amstrup, developed a model that put all of these pieces together and projected polar bear populations into the future.


So, with the research, what exactly does this research tell us? What have we learned from all of this?


Well, basically what we've learned is in an even more quantitative way that polar bears really are tied to sea ice. There are a lot of theories that they may be able to adapt to finding prey on land, and indeed some polar bears are stranded on land for a certain amount of time. But in order to feed, they really do need that sea ice platform.

And so since the sea ice is changing, what we're seeing is that in two regions of the Arctic, we would predict that polar bears will go into a steep decline within a . . . probably a 50-year timeframe.

In a third region in the Arctic probably within 75 years they would be in steep decline, or extirpated. But even out to a 100 years there's a core area in the Arctic where we will have maybe smaller, but probably still-remaining polar bear populations.

Now unfortunately for the United States, that area is not within our territory [laughing] so probably, for the United States, we will not be seeing polar bears off Alaska.


Is this research prompting more studies, and if so, what sorts of things are being looked at?


Well, one of the things that we determined during the process was that we really do need more monitoring data, both more spatially explicit monitoring data on sea ice. It's not mapped or observed near small enough scale and more data on how polar bears are responding to sea ice change. So the first recommendation would be that we do more intensive monitoring of both of those, so we can see if our projections into the future are really fairing out.

And I guess the second thing that I would say is that we found that we really need to do more linkage of physical models and biological models. And I think we really have sort of started a process here that we can now use on other environmental questions in the future, and I hope that we'll be able to transfer some of the knowledge that we've learned to other situations, droughts in the West, or coastal change.

I think some of the things we've learned will really find a fruitful home in USGS in the future. [Scott: Yes, so we can use this research across all different bases of earth science and natural sciences.] Right. That's right.


Last question I have for you is how would you respond to the criticism that this research is overly pessimistic?


Well, we get that question a lot [laughing]. And I think, in truth, some of our scientists were very surprise at these projections at how the steep the decline was that was projected for the polar bear. But I think you also have to understand that the models that we used are really optimistic about their projection of sea ice. So we consider them conservative in their decline. There's more and more literature to confirm that from sea ice models and climate change scientist.

And so, I don't consider these overly pessimistic, unfortunately, for the polar bear [laughing]. But I would like to say to that, since we are projecting out to 100 years, that there will be at least, in some parts of the Arctic, viable polar bear populations. There is time for action, and so in that way I'm optimistic.


Well, I guess that does it, Sue. I really appreciate you joining us today and taking the time to talk about the recent polar bear research from the USGS. This has definitely been an interesting interview and you've shared with us a wealth of information. We look forward to hearing what the coming years have to bring with regards to the polar bear. Thanks again.


Thank you.


And I want to think everyone for listening to this episode of the CoreCast. If you'd like to read the full reports and research on polar bears, as well as an executive summary of the research, you can visit and click the link for "New Polar Bear Research" located in the "In the Spotlight" section of that page. And that'll be in the center section to the left.

Also, we've just recently added the ability to subscribe to the CoreCast by email. So if you know anyone who might be interested in listening to our podcasts but might not be sure what a podcast is or what an RSS feed is, just tell them to subscribe using their e-mail address. It's quick. It's simple. It'll change your life. Well . . . that might be a stretch 

. . . but the knowledge you'll gain could be life changing.

CoreCast is a product of the U.S. Geological Survey, Department of the Interior. Until next time, I'm Scott Horvath saying, "Keep it cool."

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Musical credit:

"When the Levee Breaks," Kansas Joe McCoy and Memphis Minnie.

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