Polar Bears on Thin Ice: Navigating Climate Change and Conservation with Dr. Steve Amstrup

Venture into the frozen realm of the Arctic with Dr. Steve Amstrup, a leading authority on polar bears, as we explore the profound impact of climate change on these iconic predators. Throughout our conversation, Dr. Amstrup draws from his extensive fieldwork experience, highlighting the urgent challenges posed by melting sea ice and the behavioral adaptations that polar bears are forced to make. Prepare to be captivated by tales from the frontline of wildlife research and discover the meticulous efforts behind tracking and conserving these majestic animals.

Dr. Amstrup's journey from documenting polar bear population recovery to pioneering research in their conservation opens a window into the complex world of Arctic wildlife management. Our episode traverses the inventive process of immobilizing polar bears for study, the surprising discoveries from radio collaring, and the tricky techniques developed to observe these elusive giants. As sea ice retreats, we are offered a rare glimpse into the altered existence of polar bears and the innovative science that seeks to safeguard their future.

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Steve speaks extensively about a recent publication tying greenhouse gas emissions to polar bear populations. You can find that study here.

Additional links:
Polar Bears International
The Hill - Scientists link greenhouse gas emissions to polar bear population declines
CNN - Scientists say they've found a direct link between planet-warming pollution and polar bear survival 

Transcript

Dr. Monni Böhm: 0:02

Polar bears are Earth's largest land predators, despite spending a lot of time in the ocean as well. But sitting at the top of the food chain does not guarantee safety. We are at a real risk here of losing this iconic species. Today, we're joined by Dr Steve Amstrup to talk about the climate crisis and how it directly threatens polar bears with extinction. I'm Monni Böhm.

Justin Birkhoff: 0:22

And I'm Justin Birkhoff. Welcome to the Protect Species podcast, where we celebrate biodiversity and converse with conservationists. So first off, thanks for joining us this morning, Steve it's great to finally meet you.

Dr. Steve Amstrup: 0:41

Thanks for having me.

Justin Birkhoff: 0:41

Yeah, we're excited to be here, so we'll start with the basics. Can you tell us a little bit about who you are, how you came to be where you are now, and so that our listeners have a better feel for what we're going to talk about?

Dr. Steve Amstrup: 0:53

Well, I'm Dr Stephen Amstrup. I'm just retired and, having become emeritus at Polar Bears International, I've been with Polar Bears International since 2010. From 1980 to 2010, I was in charge of polar bear research for the US federal government in Alaska. I started out with the US Fish and Wildlife Service and that job function was moved to the USGS, but that didn't really change anything that I did. But there I was a dyed-in-the-wool researcher and the main goal was to publish papers about polar bear ecology and I covered all aspects of their ecology in northern Alaska. It was an interesting and very rewarding job in many ways, but one of the limitations was that, working for the federal government, I couldn't really talk very freely about the conservation ramifications for my work.

Justin Birkhoff: 1:52

Yes.

Dr. Monni Böhm: 1:55

Welcome to the Protect Species podcast. You can let go now, Steve.

Dr. Steve Amstrup: 1:57

Yeah, so, anyway, that's so. I joined Polar Bears International, which our mission at PBI is conservation.

Dr. Monni Böhm: 2:08

So tell us a little bit about the lives of polar bears. Our listeners I nearly said viewers our listeners are probably super interested in polar bears. They're very iconic. What do they do day in, day out, year in year out?

Dr. Steve Amstrup: 2:22

One of the things that I think most people don't understand, and in your introduction, Monni, you said that they were the largest land predator, but actually I like to refer to them as the largest quadruped predator, because most of the time they live out on the sea ice. They're not really on land at all, and out on the sea ice they're catching seals. They'll catch some other marine mammals, but mainly it's ringed seals and bearded seals that provide their food and they catch them from the surface of the sea ice. So seals are air-breathing mammals, but they live under the ice for most of the time and they have to come up through the ice to breathe, and I can only think it must be a terrifying lifestyle, because when they have to come up to breathe, they never know whether a polar bear is going to be there waiting for them, and polar bears are very quick to snatch them, pull them out of their breathing holes, and that's how they make a living.

Dr. Steve Amstrup: 3:18

Polar bears come to land basically for two things. Female polar bears that are pregnant come ashore in the fall of the year and create dens on land typically, and then also over much of their range and now more and more of their range. Polar bears are forced on to land by melting sea ice, so the ice disappears in the areas that they have access to the seals. They come ashore and then they're food- deprived for the period that the ice is gone. But basically they are an ice-dependent species, the most ice-dependent species probably of anything, because even the ringed seals and bearded seals can live a pelagic existence in the summertime when the ice melts. They don't need to come ashore, they don't need to follow

Justin Birkhoff: 4:26

So have we seen a shift in their behavioral ecology, in the way that polar bears are behaving, as we've seen this recession in the sea ice.

Dr. Steve Amstrup: 4:33

Well, I don't. We certainly have seen more time on land, more movements into more of what we would call extra liminal movements, exploring other habitats when the sea ice is gone. We've seen polar bears venturing far inland, for example, more frequently than they ever did before. But I don't really think of those as being behavioral changes, so much as emphasizing things that they maybe always did, but now we're seeing it more frequently.

Justin Birkhoff: 5:07

Yeah, a bigger part of their behavior pattern, out of necessity.

Dr. Steve Amstrup: 5:10

Out of necessity. Yeah, In fact, there was a paper many years ago that talked about polar bears are now preferring to use open water more frequently. Well, they were being seen in open water more, but that doesn't mean that they preferred it.

Justin Birkhoff: 5:27

Yeah. So I mean you've spent a lot of time in the field, you know, with your time with the federal government and then also your time with PBI. Look back at your field career. That really like shining moments that really filled the cup or underlined why you're so passionate about polar bears.

Dr. Steve Amstrup: 5:51

So my career covered in many ways that what I think of as a fortunate time span for polar bears, at least for understanding polar bears. Not so much for the polar bears themselves, but when I first went to Alaska in 1980, I observed, and my early papers documented, the recovery of the polar bear population in Alaska from excessive harvests that had occurred in the 50s and 60s. The harvest in Alaska at that time was, on average, over 250 bears being killed every year by trophy hunters. And then there was also a small take by local native people on top of that. But the population clearly wasn't sustaining that and that ended in 1973 with the passage of the Marine Mammal Protection Act and the International Agreement for the Conservation of Polar Bears which came about was initially agreed upon in 1975.

Dr. Steve Amstrup: 6:51

And so I came in 1980, and by then we were starting to see a thriving population that was recovering from this excessive harvest and the age structure of the population was changing. We were finding more old animals and great cub production and survival, vigorous growth. I mean everything looked really good. But then over the years and up until, oh, the late 90s, things looked really good. And then things started to change and I could see that the decline in the sea ice the time that the ice was away from the coast was starting to impact the bears. And you know, I'd heard about global warming and thought about it a little bit, but I hadn't really seen the evidence of it until, you know, actually the late 1990s, when we really almost crossed a threshold, suddenly a lot more bears on land, a lot more bears that looked hungry, were leaner, growth rates were slower and cub survival was beginning to decline. So I saw, you know, a great transition from a thriving, recovering population to a declining population.

Justin Birkhoff: 8:09

That has to be difficult, especially to have such wonderful recovery in that very short time period, and it's nice that you know you mentioned these two big pieces of legislation that really shifted that dynamic. As you know, we talk about how do we protect wild species in wild places. Legislation is a big part of it and it's something that often us, as biologists or conservationists, don't necessarily have a big hand in or shy away from, because it's something that we're not familiar with, and have you been a part of any? You know more recent legislations, as you've. You know your career in polar bears has moved forward recent legislations as you've.

Dr. Steve Amstrup: 8:44

You know, your career in polar bears has moved forward. Yeah, so the Marine Mammal Protection Act preceded my involvement with polar bears, but in the latter years, when we were able to document the impact that global warming was having on polar bears, I and my lab were instrumental in convincing the Secretary of Interior to list polar bears under the US Endangered Species Act, and so that was, I viewed, a very major accomplishment, and polar bears became the first species ever listed because of the threat of global warming to their future existence. So that was. I think I can claim some responsibility for that.

Justin Birkhoff: 9:27

We feel comfortable with you doing that.

Dr. Monni Böhm: 9:29

Absolutely. We're going to talk a little bit more about the climate crisis in a bit, but I've got one slightly less heavy question for you. So I'm just trying to imagine actually our producer Kelly is trying to imagine really, because that's her question what it feels like to stand next to a fully grown polar bear. I mean, I personally probably wouldn't advise it. It doesn't sound safe. Um, but do you remember the first time that you had your first polar bear encounter? Yeah, well and how close were you? Yeah, a few, you know.

Dr. Steve Amstrup: 9:59

I mean polar bears really are impressive and, uh, I can remember the very first polar bear that I saw from the helicopter when we were out flying over the ice looking for them, and suddenly I looked down and there's a polar bear running across the ice and my reaction was holy there's a real wild polar bear. And it was just like wow, there's a real wild polar bear. And it was just like wow. And then you get down on the ice with them and it's really impressive. The most impressive thing is that if you're down on the ice and this happened frequently during my years of study we'd be on the ice working with a bear that we'd captured and another bear would come up and when one of those big males, which they can stand nearly five feet high at the shoulder, when they're standing on all fours, that's wild. They aren't as big as a horse, but they're still pretty impressive. And when they walk up on you on the ice and you're standing there by yourself, they look as big as a house. So believe that.

Dr. Monni Böhm: 11:02

yeah, yeah, well that leads me on to my next question, because I think lots of people always think conservationists it's glamorous. Right out in the field, they're permanently working with animals. How do you, how do you, study polar bears? What's the glamour of it? And I put glamour in quotation marks here because I feel it's probably quite hard work.

Dr. Steve Amstrup: 11:29

You have a white animal living on a white environment. They aren't easy to see, they occur at very low densities, and so the

Dr. Steve Amstrup: 11:56

And then marking them and then the next year going out and catching some more. We put radio collars on polar bears. I was the first person to successfully radio collar polar bears, which opened our eyes to their incredible movements. They're the most mobile of all quadrupeds and we can talk about that more in a moment, if you'd like. But we figured out that we needed to have bears in hand so we could understand whether they were healthy, how fat they were, how thin they were, how fast they were growing if we caught them in multiple years, how many cubs they were having, and that capture recapture method going out and catching as many bears as we can is what I did for most of my career and it still is the method that I think we would all prefer to do if we could, but of course it's become increasingly expensive. Yeah, and there are some people who don't like the thought of catching and tagging bears, so in some places we just can't do it anymore. But that's how we really learned most of what we now know about polar bears.

Justin Birkhoff: 13:05

And I think it's interesting because, as you mentioned, it's a unique species living in a unique environment and we often think of like mark recapture in many senses. We use camera traps, so we're using cameras that are motion activated, you tie them to a tree and all that, and you can't do that in open sea ice. So some of these advancements in technology aren't lent to the environment itself. That would make some of these things a little bit quote easier.

Dr. Steve Amstrup: 13:33

That's right. Yeah, camera tracks have given us a lot of information, as you know, about many other species, but the polar bear's environment the sea ice is moving. Yeah, the bears are moving. The polar bears environment the sea ice is moving. Yeah, the bears are moving, and unlike the terrestrial bears, they don't maintain territories or home ranges, at least the way we think of it. Yeah, or on a scale that's just not feasible to use it. I talked about the movements that I documented with radio telemetry. When I first started, we had no idea. We knew they were very mobile, but we didn't really know how mobile. And some of the bears that I radio collared and then followed had activity areas around 600,000 square kilometers, bigger than the state of Montana.

Justin Birkhoff: 14:19

Yeah, it's a mind-boggling number.

Dr. Steve Amstrup: 14:21

We think of the great caribou migrations or the wildebeest migrations, and the movements of polar bears can dwarf all of those migrations, so they're extremely mobile. Don't quite understand why some of them are so mobile, because there are others that are kind of homebodies. But that's that individual thing, that most long-lived mammals develop, individual characteristics, what works for them. And you know, some of them were real travelers and some of them were homebodies. We all got habits, right that's right I'm looking at you justin, yeah well

Dr. Steve Amstrup: 14:55

I'm looking at both of you. I mean neither of us are from here how about that?

Justin Birkhoff: 14:59

we've shifted our home ranges in a very ecological sort of way absolutely, um.

Dr. Monni Böhm: 15:03

So going back to the how do you trap polar bears? Because I started out actually not in fresh water studying badgers or what I call, like the really tiny land polar bears. I mean practically that's a job. I was really trying hard here, um, but I assume with a polar bear you can't just set up a trap and put peanuts and golden syrup in, right?

Dr. Steve Amstrup: 15:28

They'll be like what is this?

Dr. Monni Böhm: 15:30

They will also destroy it and just go like yeah.

Dr. Steve Amstrup: 15:33

Yeah. So we would fly out over the sea ice looking for polar bear footprints in the snow, and we'd find the footprints. We'd follow them until they hopefully lead us to a bear, and then we would shoot the bear from the helicopter with a projectile syringe, a dart that contains an immobilizing agent. The bear would go to sleep, usually within three to five minutes, sometimes longer. One of the things we learned is that all of the drugs that we've used were very lipophilic. If you shoot the bear in the butt they've got a lot of fat. If they're in good shape they've got a lot of fat over their rump muscles and it might take a long time for that drug to get into the animal's body. So we would end up trying to shoot them in the neck, where heavy muscles but not very much fat. So a good shot there, three to five minutes. They'd be immobilized and we would land next to them and then we would weigh them, measure them, mark them, put a radio collar on them.

Dr. Steve Amstrup: 16:33

If they had cubs, we would do a little sort of a rodeo event where we'd have the female on the ground and the cubs would automatically want to go to their mother, the ground and the cubs would automatically want to go to their mother, which is now asleep, hopefully, and then we would get the crew, the helicopter pilot, myself and my assistant and sort of come in from a triangle and keep them on the mother until we could reach in and grab them. And then we'd grab them and then we could hand inject the cubs. We wouldn't want to dart them because a dart would hit them too hard and would cause serious injuries for an animal that size. But that's how we did it and sometimes there were some real adventures in the capturing of the cubs as well as their mothers.

Dr. Monni Böhm: 17:18

Are there any particularly good stories? Sorry?

Justin Birkhoff: 17:21

On the tail of that as well. Are there any particularly good stories? How did you learn to hand grab a polar bear cub like what? Who looked at you like, all right, this is what we're going to do.

Dr. Steve Amstrup: 17:30

And you're like, yeah, that sounds great, let's, let's do that I suppose well, it was sort of a something I had to learn myself okay and uh necessity you know, but one thing you wouldn't want to grab any strange animal and give them much of an opportunity to bite you, because if they can, they will.

Dr. Steve Amstrup: 17:48

I agree with that, and so you want to make sure you grab them by the scruff of the neck and hold them well enough that they can't turn around, which many times wasn't entirely successful. So we got a lot of puncture wounds from those little deciduous teeth that the polar bear cubs have. But once we would give them an injection then they would slow down and we could just leave them laying there by the mother while we were working on the mother.

Justin Birkhoff: 18:15

We'll point out for our listeners that Steve has all of his fingers. So if anyone's concerned, yes, and most of them, not just all of them.

Dr. Monni Böhm: 18:26

He's got 10 fingers. They're all stumps no stumps.

Justin Birkhoff: 18:30

you save money on manicures that way. Yeah, yeah, um, so we alluded to it, that was a question that we're going to come back to, and polar bears are really kind of poster child doesn't feel that way where it is really kind of a symbolic species that a lot of us have connected with through our lives because they are so fascinating, they're large. There's something very you know, charismatic is the word we use a lot, but we can't talk about polar bears without talking about the climate crisis we're in and you've alluded to it. That you know really started to become evident in your research in the late nineties and early two thousands, you know, can you give, you know, if you were going to give somebody the elevator pitch of what is the climate crisis and how it's being realized in the Arctic, what would that be?

Dr. Steve Amstrup: 19:12

Well, let me start by giving you an example of what I think is one of the most profound experiences in my career up there, when I first went to Alaska in 1980, I could stand on the beach of northern Alaska Prudhoe Bay, point Barrow, near the village of Coctovic, next to the Canadian border, and in the late summer I could look offshore and the sea ice was usually easily in view.

Dr. Steve Amstrup: 19:39

There might be a band of open water between the coast and the sea ice, but the ice was still right there over the shallow continental shelf water where the high productivity is. And at the end of my career, same time of year, you couldn't see ice at all because it had retreated so far north. It was beyond the curvature of the Earth. The most powerful telescope couldn't resolve it because it was over the curve. And just thinking about that and knowing that the bears preferred and my radio telemetry data showed clearly, the bears preferred to spend their summer on the near shore ice when there wasn't any near shore ice, you don't really have to do any analyses to realize this can't be good for bears.

Dr. Steve Amstrup: 20:26

And at the same time then, of course, when I first went to Alaska, the oil field workers at Prudhoe Bay, where one of the biggest oil fields in the US is. Many of them hadn't ever seen a polar bear. They thought polar bears were some kind of a figment of people's imagination because they weren't coming ashore in those early years. Now they see polar bears all the time and they have polar bears alerts in the oil fields, and so those are things that, even without studies, you can realize something seriously has changed.

Dr. Monni Böhm: 20:58

So what would you say to those folks who might well I mean, most of us will not see polar bears in real life, but who might have seen footage or live up where polar bears are and see them on land? And they go like, well, they're here, right, it's like they're doing all right, we just saw I don't know one today. Why can they not really adapt to become like a predator on land? Why is the climate crisis such a big issue for them?

Dr. Steve Amstrup: 21:24

Well, so polar bears have become the largest bears in the world because of their rich food source, which is seals basically ringed and bearded seals and you can. Polar bears can only catch them from the surface of the sea ice and so you can think of them as giant fat pills out there waiting for the bears to go around, and they can't just pick them up. It's a, you know, predator, prey interaction and most of the time the seal gets away. But it's a highly energetic resource that has allowed polar bears to become so large. If you compare, in northern Alaska and other places where grizzly bears occur very far north, those grizzly bears are the smallest of all of the brown bear group anywhere. They're not very big bears at all and they reproduce very slowly and they live at very low densities. So think about that. Ice goes away. You've pushed all those polar bears onto shore. What kind of imagination would you have to have to think that an environment that currently supports only small numbers of very small bears is going to support whole populations of the world's largest bear?

Justin Birkhoff: 22:34

And not only that, it's going to have to support both simultaneously. Yes and it's. You know the resources of it, you know the pure economic model of it just doesn't work Right.

Dr. Steve Amstrup: 22:45

And if you think of it from a competitive standpoint, I mean species out there are competing with each other all the time. The grizzly bears may be small, but they have figured out how to make a living there. You take polar bears on to shore and there's a learning curve.

Dr. Steve Amstrup: 22:59

Yeah, they're beginning the learning curve and they probably aren't going to survive it. And in fact, if you go back to the end of the Pleistocene, we know that polar bears occurred as far south as the Baltic Sea when the ice retreated during the Holocene. As the ice retreated, those polar bears that no longer had enough ice to support them in the Baltic, they didn't make a living on land, they didn't move onto land and figure out some other way to live, they just disappeared yeah.

Justin Birkhoff: 23:34

And so I mean this leads us into you know, kind of a sobering question is often we talk about polar bears, we talk about the climate crisis, we talk about these bears disappearing. We talk about this species that you know. It doesn't really matter where you are in the world. People know what a polar bear is or have seen photos and that sort of stuff. We often talk about it as kind of this doom and gloom sort of like polar bears are going to disappear. Do you think that's true? Do you think there is a way that we can halt this extinction and reduce their risk and their threats enough that this population could potentially rebound again?

Dr. Steve Amstrup: 24:06

Well, we absolutely still have time to save polar bears over much of their current range, and I think that's really an important message. We know that if we allow the sea ice to continue to deteriorate, to continue to disappear, that we won't have polar bears. Maybe we could say there might be some small relic populations that can figure out a way to live by catching seals that haul out on land or something like that, but we don't have any evidence that that will really happen and it certainly wouldn't be anything like the current abundance and distribution that we have. But we still have over 20,000 polar bears globally. So when you think of a threatened species, compared to some others, polar bears are really in pretty good shape.

Dr. Steve Amstrup: 24:55

They were not listed under the ESA because of their current population status.

Dr. Steve Amstrup: 25:00

They were listed because of the understanding that if we allow global warming to continue, polar bears won't persist.

Dr. Steve Amstrup: 25:08

But we can stop global warming in time to save polar bears over much of their range. They live over a broad reach of the Arctic, from elevations that are about the same as Scotland, in the southern part of Hudson Bay and in Davis Strait, up to the very top of the world, and so there's room for polar bears to continue to persist. But time is really of the essence and one thing that you mentioned we can't really see a rebound unless we can pull carbon dioxide out of the air. We can halt the warming and stabilize it and in fact, in our 2010 paper in Nature, we showed that if you stabilize the emissions, that if you stabilize the emissions, if you halt current emissions, stabilize the concentration, that in fact the ice will recover. It'll dip for a little bit and then it'll come back to a lower level than it is now, but it will come back and stabilize and that stable ice will then be habitat for polar bears, at least over much of their current range.

Justin Birkhoff: 26:16

Okay, that's good news, yeah.

Dr. Monni Böhm: 26:25

Let's talk a little bit more about policy, then, because I feel that policy is very much key to kind of saving these animals right, Whether it's climate policy or obviously also their protected status and so on. Can you tell us a little bit about kind of what would you like to see in terms of a policy framework that obviously is related to climate, but really kind of what would you like to see in terms of a policy framework that obviously is related to climate but really kind of takes into account also what the polar bear needs? That's kind of essentially like this lifeline for the polar bear.

Dr. Steve Amstrup: 26:47

Well, the lifeline for the polar bear is to halt the rise in concentrations of greenhouse gases, and in order to do that, we need to stop emissions. Now we're making headway that direction, but we're making headway very slowly and so we need to. I mean, there's a lot of things that we can do on the ground protecting areas that might be subjected to oil and gas development or mining, and things like that and those are important but the more important aspect is to halt the greenhouse gas emissions that accompany those kinds of developments, and if we don't do that, we aren't going to save polar bears. But again, we have time to do that and we can.

Dr. Steve Amstrup: 27:33

One of the things that is definitely a policy-related issue that I've been working on for 10 years to try and solve is the dilemma that when polar bears were listed in 2008, they were listed because of the threat posed by anthropogenic global warming, but the US Department of Interior the solicitor of the Department of Interior at that time came up with a ruling an opinion that became policy stating that ESA considerations Section 7 consultations cannot include emissions from projects that are being considered unless you can link the emissions from that specific project directly to an effect on the polar bears, which means you would have to be able to separate those emissions from all historic emissions going back to the beginning of the industrial era, and so we've had polar bears listed under the Endangered Species Act for 15 years, but we haven't been able to consider the reason that they were listed in the first place, which is emissions of global warming gases.

Dr. Steve Amstrup: 28:48

There's a lot of colorful language for that.

Justin Birkhoff: 28:49

Absurd is the one I'm going to use. I was going to say, yeah, I'm just looking confused.

Dr. Monni Böhm: 28:53

It's like what's going on? I mean I'm not from here, so I'm just looking confused. It's like what's going on? I mean I'm not from here so I'm like I don't know what's happening.

Dr. Steve Amstrup: 28:58

It's confusing for us too, yeah, and in fact, I think most people in even the polar bear research and management community weren't really aware that that had happened and, you know, I think most of them were aware that nothing was really being done to address emissions as they might affect polar bears.

Justin Birkhoff: 29:17

It almost feels like the listing feels somewhat symbolic and hollow at that point, right Exactly, we have this species, we have a really good understanding of what is impacting it and causing this decline in it, but that's it Like that's as far as this was willing to go. Yeah, and so you have a new publication out and you kind of could dive into detail and address this a bit. What is really the kind of the key takeaways from this new publication?

Dr. Steve Amstrup: 29:46

Yeah.

Dr. Steve Amstrup: 29:46

So the challenge in this policy that you have to be able to separate the emissions, to be able to parse the emissions from any particular project or action from other emissions and the impact of those emissions.

Dr. Steve Amstrup: 30:03

In order to address that, it required two things. The first was to link a change in the polar bear's habitat, the sea ice, to polar bear demographics, and I and many other scientists had for years been doing estimates of population size and recruitment rates, survival rates, that sort of thing and trying to link that to the changes in the sea ice. And we were looking at sea ice area, sea ice volume, sea ice extent and we really couldn't come up with a quantifiable link between polar bear demographic welfare and sea ice. But in 2020, we did a paper, my colleagues and I. It's a paper led by Dr Peter Molnar at the University of Toronto. I put this group together to address that question and what we showed in that paper was that if you reduce everything to polar bear energy, how much energy they have in their body at the start of the summer fasting season when they're forced onto land, that that is the link to their reproduction and survival.

Dr. Steve Amstrup: 31:16

Yeah, that makes sense, and we showed that that was related to the number of ice-free days that drive their fasting duration in the summertime. So ice-free days is an attribute of the sea ice that we hadn't really looked at before. Okay, but when we kind of flipped the analysis of survival on its head and said, well, what really regulates survival? Well, it's how much energy these animals have.

Justin Birkhoff: 31:42

I want to interrupt with this how do you calculate how much energy an individual bear has at the beginning of the season.

Dr. Steve Amstrup: 31:47

So Peter in his earlier work looked at the energy balance, the mass of polar bears and how much of that was useful energy for each individual sex and age group. And that way I mean you can't, for example, take advantage of the energy that might be in your bones or in your muscles. You can sacrifice some of that but you can't go very far with it or you're not going to survive. So how much energy do bears have for continued survival, for growth and for reproduction? And he worked out the models that predict what all of that is, depending on the length and mass of a bear okay, because I did did some research with with elephant seals as an and one of the things we that's really enormous fat pills, isn't it?

Dr. Monni Böhm: 32:38

Yes, they were. I've now learned from Steve that I should just call all seals fat pills.

Justin Birkhoff: 32:43

One of the things that we looked at was when animals were coming back from their foraging adventures. It was looking at what their blubber layer was. We did it with ultrasounds. I mean, I'm assuming there was some of that sort of baselining with this, this model that was produced for polar bears. Okay, so again we go back to that like bears in hand, like this is where the value of this sort of these sort of opportunities come from is that you're able to measure this whole host of data that may not be useful at the exact moment you're gathering it, but has has applications further down the road?

Dr. Steve Amstrup: 33:16

Absolutely, and your elephant seal example is great. If you didn't have elephant seals in hand, if you weren't able to walk up to them and do the ultrasound, you wouldn't. You wouldn't have any idea what their fat content was, but that fat content is what's critical for them. Pretty consistent too.

Justin Birkhoff: 33:32

And like I think that's the thing is that you start to model it out. As for them and it's pretty consistent too, and like I think that's the thing is that you start to model it out as you know, we could take a look at how long the seal was and then, based on what its body condition score is, so what's you know kind of a somewhat subjective but based on an objective scale system from a distance, have a rough idea of how good of a condition they were, and then you could calculate, and then we were able to ground truth that with the ultrasound. So I'm assuming the Bayer system works very similarly, Okay, Similar, similar concept.

Justin Birkhoff: 34:03

This podcast is a production of the Global Center for Species Survival of Indianapolis. We record all the episodes in the Beatle Financial Media Studio, made possible by a generous gift from Eric and Elaine Beatle.

Dr. Monni Böhm: 34:21

I've got one really quick follow-up question Of course it might be a really silly one again. How do you weigh a polar bear?

Justin Birkhoff: 34:27

No, that's a great question, especially on sea ice.

Dr. Monni Böhm: 34:31

With all the difficulties. I can understand the measuring. It's already asleep, right Tape measure or something Fine, cool.

Justin Birkhoff: 34:37

Tape measures are important too.

Dr. Monni Böhm: 34:38

But how do you hoist a polar bear? What do the scales look like? Lots of questions.

Dr. Steve Amstrup: 34:44

Well, we used a digital scale and we developed. What I did is I got a, got a hold of some aircraft aluminum tubing, so it was lightweight and we could slide one one tube inside the other, basically, so you could go from and make a tripod out of it, so the legs of the tripod, telescope, depending on the size of the bear, how high you have to go. And then I made a head for the tripod that was heavy enough to lift like an engine from a car. So we knew we had strength, that the thing wasn't going to fall down when we or collapse when we were picking up the bears. Roll the bear, the immobilized bear, roll the bear into a net, hook up the corners, hoist it up with a winch.

Dr. Steve Amstrup: 35:30

I actually used an automotive chain winch because you could work awfully hard with one of these hand cranking things and it took a long time. The chain winch you could just pull the chain down and the mechanical advantage was enough that you could lift the heaviest bear, and I think the heaviest bears we ever did were around 1400 pounds.

Justin Birkhoff: 35:51

That is a lot of.

Dr. Steve Amstrup: 35:52

I love the fact that a lot of field work is essentially just diy right.

Justin Birkhoff: 35:56

It's like solving problems.

Dr. Monni Böhm: 35:57

It's like what can I put together to make this?

Justin Birkhoff: 36:00

we mentioned the same. We did something very similar for the elephant seals, except for the big males, because they were just they're physically too large to do it. I mean a full-size male elephant seals, along as a pickup truck. Yeah, so that one. They they buried a scale in the sand and then they'd have somebody run in front of a male and they'd chase it. It's some of. Some of the things have changed, but it's where there was.

Dr. Steve Amstrup: 36:23

Also there was a fake model female risk assessment.

Justin Birkhoff: 36:26

There was a risk assessment, which is why they don't do that part anymore, but it is interesting, as you mentioned is like you know you were one of the first people to put. You know, to put radio telemetry on a bear is like there's no handbook, right, like you have. You're like, well, these things should work. And use the word hope a lot. It's like we hoped we could find a bear. We hoped it wouldn't wake up. So there is that kind of that. You know the the art and science of it all and you mentioned we a lot. So how big was a team for some of these things? The?

Dr. Steve Amstrup: 36:54

the typical team going out to catch polar bears was two biologists and a pilot.

Dr. Monni Böhm: 36:59

It's not a big team no, it's not so if you catch a thousand pound bear. It takes a fair amount. You work up takes a fair amount.

Dr. Steve Amstrup: 37:05

You work up a sweat. All three of you work up a sweat trying to get it into the net. Burn some calories.

Justin Birkhoff: 37:09

Yeah, but we're going to go. We've gone off on a tangent. I wanted to go back.

Dr. Monni Böhm: 37:13

I was just trying to assess. You know how much larger the research budget is for polar bears compared to badgers.

Justin Birkhoff: 37:20

A lot, yeah, a lot larger A scale that you don't want to think about. So we go back to this publication and we talked about, like energy, you know, energy that bears the beginning of the season oh yeah, we're getting back directly related to ice free days and that this is a metric that we can use to measure back towards emissions for singular projects.

Dr. Steve Amstrup: 37:41

Yeah, so in 2020, we published that paper in Nature Climate Change, linking ice-free days to polar bear survival and recruitment. Okay, okay. So we have a metric of the sea ice that's directly related and this is based on the best available data that we have directly related to the condition of the bear and its ability to survive and reproduce. So after we published that in 2020, I thought well, wait a minute. If we can come up with good estimates of emissions, we can link emissions just by simple regression to the number of ice-free days, which we did, and so we published this paper in Science. It came out at the 1st of September 2023.

Dr. Steve Amstrup: 38:33

Yeah, so it just came out within the month, and what we showed is that not only can we link emissions to ice-free days, but we can carry that regression forward, propagating the errors and everything all the way through to survival. And so that's what we did. So now we have a direct relationship between global emissions and the survival. So I'm going to back up a little bit. We could have done this for any of the sex and age groups, ok. So we could have looked at adult males, we could have looked at solitary females, but one of the things we know is that if a population isn't recruiting young, it's not going to persist. Yeah, it's a false number that's right.

Dr. Steve Amstrup: 39:26

So adults actually are. An adult polar bear is a pretty durable animal. They can fast If they're in good shape. They can fast for a long, long time. But if a female isn't in good enough shape, doesn't have enough fat to provide enough milk for its cubs, the cubs are not going to survive. And in fact, that's the first thing that we see. We've seen it in Hudson Bay. We see it in the southern Beaufort Sea, where I did most of my research In the Barents Sea, the places where we know about bears. We know that the first thing that suffers is the survival of cubs. So that's the aspect that we focused on in our paper, and we were able to show that recruitment of cubs is directly related to global cumulative emissions. But what that also means is you can use the same formula to say well, if we develop oil and gas off of the coast of California and it produces this many gigatons of CO2, this is the impact that's going to have, so we can address.

Dr. Monni Böhm: 40:33

We're closing the loophole. That's right, that's awesome.

Dr. Steve Amstrup: 40:36

So this was like a 10-year quest for me to figure out how we can get to this point, and finally this month we showed in the journal Science that we can do that. So we have the ability, then, to not only identify what the impact of any particular action or group of actions might be, but it turns out that if you look at what the impact based on this analysis what should the impact have been on recruitment, once exactly matches the other information that we have?

Dr. Steve Amstrup: 41:15

about how the best known polar bear populations are responding, and so we have a totally different way to look at all of the evidence or to come up with evidence for the declining, or what's causing the declining numbers of polar bears so I have two follow-up questions that are somewhat related to each other about this.

Justin Birkhoff: 41:50

so one is we talked about new developments, right? So new things that would be producing emissions. Could we use this model system that you've, you know, this publication, to look at what happens if we take x company and it reduces its actual emissions not the, you know, you know the buy-off, you know the, that right, the carbon credit scheme but like reduces its actual emissions? Can we then back calculate how this can improve polar bear populations as opposed to negatively impact it?

Dr. Steve Amstrup: 42:19

Yeah, or how much would it diminish the negative? Okay, uh, the negative.

Justin Birkhoff: 42:24

Yeah, that's probably a better way of framing it.

Dr. Steve Amstrup: 42:25

Yeah, yeah, because as long as we're continuing to put out greenhouse gases into the atmosphere, we are impacting polar bears, and so then the second question is you know you don't want to diminish this massive accomplishment.

Justin Birkhoff: 42:40

You said it was 10 years in the making and it's freshly out. How do we take a publication like this and apply it to policy?

Dr. Steve Amstrup: 42:49

Well. So the most initial or the first level of applying it to policy is to overturn what we call the Bernhardt memo, which was the memo that was written by the solicitor of the Department of Interior in 2008. And we now know that we can meet the requirements that Bernhardt specified, so we no longer have to follow that policy and Section 7 consultations within the Endangered Species Act can include greenhouse gas emissions. That's huge because they just haven't looked at. We haven't been able to look at that Now. Beyond that, this regression method of linking emissions to sea ice free days and onto demographics that can be applied to a whole bunch of other species. Think of global sea level rise and its impact on beach nesting birds like penguins, like Pablo's penguins that we're going to hear about this week, you know.

Dr. Steve Amstrup: 43:59

Or beach nesting marine turtles, you know, um so, and uh corals, relating uh ocean temperature to the frequency of bleaching events. If we look at the uh, look at emissions instead of looking at global concentrations, we can make these kind of regression relationships and suddenly we have a way to link, to make that vital link for a whole bunch of species and groups of species that are also imperiled by climate change. That is, absolutely huge.

Dr. Monni Böhm: 44:36

A few follow-ups. Pablo, of course, refers to our Indianapolis Prize winner, who's in Indy this week for all of the events. So just for our listeners to get the context, and this is obviously also why steve is here um to celebrate with us as a past winner as a past winner as well.

Dr. Monni Böhm: 44:55

um, my real follow-up question, though, is how does it feel when you have done tried for 10 years to kind of find a way of essentially fill this loophole, find this connection, and then you see this paper published. What does that feel like? Having never reached those heights?

Dr. Steve Amstrup: 45:13

in academia myself.

Dr. Monni Böhm: 45:15

I just really want to kind of you know, vicariously, live through you.

Justin Birkhoff: 45:19

You say that I'm the only person here whose title doesn't include the term doctor, so you're ahead of me.

Dr. Monni Böhm: 45:24

Oh yeah, but I mean mean you can maybe maybe we need to edit this out, but you can get the title of doctor and never have this eureka moment that's a very good point to be quite honest well it?

Dr. Steve Amstrup: 45:35

I have to. I guess my response is a couple of things. First, I'm thrilled. I'm thrilled that we got this into science, which is science and nature are the two most prestigious papers. I published kind of the theory, the concept of the relationship between global warming and polar bears, in 2010 in nature, and now the resolution of exactly what that relationship is in science, 10 years, 13 years later. To me those are great bookends and I feel very, very fortunate that I have been able to do that, so I'm really happy about that. It is kind of bittersweet in that it took us 15 years after polar bears were listed to get to this point, and sometimes things in science take some time to figure out.

Dr. Steve Amstrup: 46:35

Okay, how do we put these pieces together? How do we have an understanding of what the pieces are, and then are we able to put them together? But having said all of that, the joy of seeing this in print and realizing the ramifications for so many other ecosystems and forms of life, I think uh is important. Uh, and you know we've been trying to figure out well, how do we model if emissions continue on this scenario or this scenario or this scenario? You know climate modelers are always talking about these different scenarios of future emissions. If we pick one of those or several of those, what does that mean for polar bears? What does that mean for corals? What does that mean for all these other species? We now have an ability to much more accurately predict what it actually means.

Justin Birkhoff: 47:28

Yeah, we get a much finer detail and answers that are more tangible.

Dr. Steve Amstrup: 47:32

Yeah, yeah. One other thing I should point out is that this paper in 2020, peter Molnar's analysis looking at the energetics how much energy is in a polar bear's body? The energetics how much energy is in a polar bear's body the polar bear's requirements to be able to survive and reproduce in the future, that's not likely to change very rapidly. You know there are many parameters we could measure that will change, just as the sea ice is changing and as the other aspects of the climate are changing, but that's going to be relatively stable. So we've got one less variable that's very changeable to consider when we're modeling what's likely to happen in the future. And so I think that was really another very important part of that 2020 paper that it switched it from looking at estimates that we calculate from capture, recapture of survival rates to something that is not going to change. We know those estimates of survival rate are going to change somehow we don't know exactly how, but that stability in polar bear energetics is not likely to change. Not at all.

Dr. Monni Böhm: 48:50

How can our podcast listeners find out more about this work?

Dr. Steve Amstrup: 48:55

So if you go to the Polar Bears International website and that's polarbearsinternationalorg. Original.

Dr. Monni Böhm: 49:03

Very simple yeah.

Dr. Steve Amstrup: 49:04

It's easy dot org. Very simple. Yeah, right now there's a link that's called I think it's called Breaking News on the homepage at Polar Bears International. If you click on that link, it takes you to a link from which you can download the actual paper for free. Phenomenal, and if you're familiar at all with science you know that in the journal science typically you cannot get the papers for free.

Dr. Steve Amstrup: 49:32

There's a paywall, but we have gotten permission to post this on our website and people can download the paper for free. Also there there's a little bit of an outline of the history of getting to this point, of the different landmarks that we crossed in order to make this paper possible, and I think also there's some of the recent media posted there that what people wrote about the paper when it was, when it was released, and because it had major policy ramifications, it actually got pretty good coverage as scientific papers go.

Dr. Monni Böhm: 50:09

Amazing as it should, Cause it seems like a right yeah no, it is.

Justin Birkhoff: 50:13

I mean, it is an absolutely phenomenal moment and you know, you can't, you can't undersell how impactful this can be. I really can't.

Dr. Monni Böhm: 50:24

No, we are a bit emotional, Steve.

Justin Birkhoff: 50:28

So I have. I have one last question for you, Steve. So when you talk about your career as it spans polar bears, when people say, you know, tell me a story about your life with polar bears, what is the one story that comes to mind first?

Dr. Steve Amstrup: 50:54

first. I guess I guess the I don't know if you'd say it's a story, but the thing that really sticks in my mind and this also is bittersweet is that in my career I was able to start working on polar bears when polar bears were really thriving, and so I could see what a healthy, flourishing polar bear population looked like. By the end of my career it was kind of the opposite of that, and that's what really sticks in my mind is that I have that breadth of experience that somebody who's coming into the polar bear world now isn't going to see.

Dr. Steve Amstrup: 51:28

That it's kind of this concept of shifting baselines that we talk about in ecology a lot, and we talk about this new normal, and so I guess that that's the thing, that, in my career experience, that's what really sticks in my mind.

Dr. Steve Amstrup: 51:53

But the other thing that I want to emphasize again is that we know from my research and the research of all the other people around the world who are studying polar bears is that we still have time to save them, and it's going to take action. It's going to take getting away from the denial that our political leaders have been involved with for all these years. I mean, we knew since the 70s that global warming was going to be a real challenge, and we've had too many people just hiding their heads in the sand people just hiding their heads in the sand and you know it's time to start asking today's political leaders you know, what did you do when we knew that we were facing this crisis and you had the power to do something about it? What did you do? I think most politicians are concerned about the stamp that they'll leave in history, and I think many of them are currently on the way to not leaving a very good stamp.

Dr. Monni Böhm: 52:52

And just briefly talking of people, the climate crisis obviously seems overwhelming to the individual. But what can the individual do, I mean, apart from maybe asking tough questions of their political leaders, of course?

Justin Birkhoff: 53:05

And votes. That's one thing. Yeah, where your vote goes is a big thing as well.

Dr. Monni Böhm: 53:10

What else can individuals do?

Dr. Steve Amstrup: 53:12

Well, yeah, so the most important is the vote. Vote in the ballot box and vote in the marketplace. Support companies that are doing the right thing, that are trying to develop or have developed sustainable business models. That's what it's all about. I mean, global warming is the epitome of a non-sustainable event, so we can support leaders who believe that we need to do something, either our policy leaders or our business leaders.

Dr. Steve Amstrup: 53:44

And the other thing to remember, though, is we all can make changes in our daily lives, and you know it used to be that we talked only about sort of these low hanging fruit that, oh well, I can turn off the lights when I leave the room, I can turn my thermostat down in the wintertime and up in the summertime, and that sort of thing, and you know a lot of those. Now we don't hear much about because it seems like we're beyond that, but global warming is death by a thousand cuts, and everything that we can do, no matter what the scale is, will help, and as we're doing those things, we broadcast it to our neighbors, to our friends, that oh, you know what I'm doing to minimize my impact. Share it. Share it with your social groups, the people you go to church or synagogue with, or whatever, share it with the people that you interact with and get them to change their ways. And then, of course, supporting the right leaders.

Justin Birkhoff: 54:51

It's fantastic.

Dr. Monni Böhm: 54:52

Awesome. Thank you so much, Steve. Thanks for coming in and talking to us so eloquently about polar bears and also about this amazing eureka moment you had. That's a massive game changer.

Justin Birkhoff: 55:03

That's incredible, massive game changer. That's incredible. We really do appreciate you taking the time and we're happy to share this. You know this wonderful accomplishment and see how we can continue to amplify it and push it forward, to continue this wonderful change.

Dr. Steve Amstrup: 55:16

I am happy to have had this opportunity and I'm really grateful that you will be pushing out this information, because the more people that hear about it in different ways, the more likely we are to take the action that we need in time to save polar bears. And, as I was able to say in the paper which is the first time I've ever had a journal, I've tried this many times that paper in science closes with and if we say polar bears, we're going to benefit the rest of life on earth, including humans.

Dr. Monni Böhm: 55:52

It's very true, and so I feel that's a very good point to stop this recording as well, because that's a poignant moment which I now ruined.

Dr. Steve Amstrup: 56:05

Oh, you didn't ruin it, you didn't do any good, but you didn't ruin it.

Dr. Monni Böhm: 56:13

Fair, fair, fantastic, okay, awesome. Thank you very much, steve. Thank you.