Polar Bears

The Arctic is one of the fastest warming places on Earth with many negative consequences for polar bears. The ecologist and team member at Polar Bears International, Dr. Louise Archer, gives us an insight into how polar bears struggle to survive and what we can do to help.

Topic

Science, Sustainability

Type

Article | 08:11 min read

Portrait of

Dr. Louise Archer

Location

Toronto, Canada

Photo by Churchill

“Polar bears can overheat quickly in warmer temperatures, so when polar bears are on land in the summer, you actually see them spend most of their time just keeping cool, not wasting too much energy. They will dig a little area into some seaweed or into the soil to lie out and shed excess heat.”

Dr. Louise Archer

Please tell me about yourself

I’m a postdoctoral fellow at the University of Toronto, Scarborough. My work has been focused on how different species respond to global change. I look at what all of the changes we’re seeing, particularly temperature changes in ecosystems, means for species at a different variety of levels – from individuals through to populations through to communities and ecosystems.

For the past two years, I’ve been focused on polar bears and how polar bears are responding to the rapid Arctic warming that we’re seeing right now and have been seeing for the last several decades. My work is focused on how much energy polar bears take in and use on a daily basis and how their energy requirements and ability to obtain energy from the environment has been changing as their environment has changed.

What kind of measurements do you do?

I use a lot of maths, a lot of number crunching on computers to try to understand what different scenarios of global change could look like for polar bears in the future.

I integrate different types of data that’s collected by field-based researchers, some of whom have been working on polar bears for many years. They have collected really valuable information, particularly on what we call the “straight line body length” of a bear. It’s what we use to assess the size of a bear and how a bear is growing through time.

Another measurement that really feeds into this work is the weight of a bear. This is a good indicator of how much body fat they’re carrying, which is really important for understanding how much energy they’re holding and what kind of body condition they’re in.

On a broader scale, we also look at how populations are faring through time by modelling polar bears’ energy needs. So, whether populations are declining, stable, and how survival is impacted by these kinds of changes as well. And then, really important is the environmental data. Polar bears are very tightly linked to the sea ice environment that they live in. Being able to integrate data on how the environment is changing is really important for understanding what is happening with polar bears right now and what will happen in the future.

Photo by Kt Miller

Where do polar bears live? How big is the area?

We find polar bears distributed across the Arctic in five different states, which is what we call the range states where polar bears range. You find the majority of the world’s polar bears in the Canadian Arctic, but also in the US in Alaska, in Russia, in Svalbard, Norway, and also in Greenland.

Polar bears need sea ice as a platform to hunt. So, you find them distributed in areas where Arctic sea ice forms. What is also crucial to polar bears is being able to survive and persist areas where the waters are productive enough to support them. You’ll typically find polar bears in shallower coastal areas. Ideally, you want sea ice forming, but really thick, multiyear sea ice does not let enough sunlight penetrate through, which is needed for algae development in the sea ice. And that is what fuels this entire Arctic food chain.

Right at the top of the Arctic, around the North Pole, does not have the kind of productivity that the polar bears rely on for having enough opportunities to forage. And we don’t get polar bears in the Antarctic.

We like to think of the sea ice as almost like the soil in a forest. It’s what provides the base for the entire food chain to grow. When you have sunlight penetrating through, algae will start to photosynthesize. That provides the energy, which is then moved through the Arctic food chains. You’ll have small microorganisms that will feed on the algae, and these will fuel fish in the area. You then get seals, whales, and other marine mammals feeding on the lower food chain levels. Right at the top, you have the polar bears. They’re your apex predator. In the Arctic food chains, they rely on each link of a chain and energy flowing through the food chain. And it all starts with the sea ice. Having ice that is thin enough to allow sunlight to penetrate through, but also thick enough to provide a platform for polar bears to hunt on. The Arctic ecosystem is a very fine balance and everything depends on each other.

Photo by Dmytro Cherkasov

Photo by Erinn Hermsen

What happens when hunting opportunities for polar bears change due to climate change?

Polar bears have always been pretty good at being able to go long periods of time without a meal. The nature of sea ice is dynamic. It’s changing. They may go for weeks or even months at a time without a meal, particularly in areas where the sea ice melts each year. But what we’re seeing now is that these annual periods without sea ice are stretching longer and longer, and bears spend more time without access to prey. In the southerly areas of their range, they have fewer and fewer days spent on the sea ice when they can hunt.

Polar bears require sea ice to be able to hunt effectively. They’re really well adapted to hunting seals on the ice. When they don’t have sufficient time on the ice, that’s when they start to become a little bit energetically stressed. Maybe they have insufficient time on the ice to accumulate enough fat reserves that will fuel them through these periods of time when hunting opportunities aren’t so good. That’s when you start to see bears become skinnier and in poorer body condition; when they’re really pushed to the limits of just how long polar bears can fast for.

The Arctic is warming at more than two times the speed of the rest of the world. Even more recent estimates suggest that it’s warming four times faster than the rest of the world. It really is one of the fastest warming places on Earth and that is causing this rapid sea ice loss and all of these negative consequences for polar bears. It is something we’re really concerned about.

Photo by Erinn Hermsen

Can’t polar bears hunt on land?

When you have a polar bear on land, they’re really not as effective a predator at all. They’ve spent a lot of time adapting to being ice-based hunters. Everything from the colour of their fur that is really well camouflaged against the snowy ice conditions, to the shape of their head and their teeth, all makes them really specialized hunters in attacking seals from the surface of the ice.

In the Arctic and subarctic, there’s nothing on land that has the energy content like seals. There aren’t really the resources available to support polar bears on land. They can overheat quickly in warmer temperatures, so when polar bears are on land, you actually see them spend most of their time just keeping cool, not wasting too much energy. They’ll be lying down a lot in what we call daybeds. They will dig a little area into some seaweed or into the soil, and they just chill out there for days at a time, just resting, conserving energy.

Chasing down a caribou or anything like that is not practical from a polar bear’s perspective. They would be in danger of overheating and their low chances of even catching prey makes it more beneficial for them to wait out that time on land until they can get back onto the ice and start hunting seals again.

Are polar bears in danger of extinction?

Polar bears are listed as vulnerable by the International Union for the Conservation of Nature Red List. IUCN is the body that classifies the status of species at risk or not at risk from extinction. The polar bears are vulnerable because of climate change and habitat loss. Continued sea-ice loss is likely to make areas incompatible with polar bears’ survival. They do need sufficient time on sea ice each year to be able to hunt.

With the ice disappearing and with periods of ice-free days extending, many areas will become unsuitable for polar bears. And we’ll start to see the species probably go locally extinct in certain areas. There is between 22,000 and 26,000 polar bears in total currently across the Arctic. However, what we will expect to see if we don’t see any changes in current emission levels and rates of climate warming, is that the polar bears won’t be able to persist in large areas of the ranges where they are right now. So, currently they’re vulnerable due to the sea ice loss.

Have you seen a decline in polar bears?

We’re seeing a decline in three populations and we just don’t have good enough information on other populations. But we can say that no populations are increasing in the long term. In western Hudson Bay, in the southerly edge of their range, we have seen a clear decline in the polar bear population. In early 1980s, we had around 1200 polar bears there, now estimated to have declined to a population of 618 polar bears. We know within the last five years there has been around a 27% decline in that population. So, it does seem to be declining quickly. This is a population that has been experiencing longer and longer periods on land because of the increased sea ice melt in that area.

Why do we need polar bears?

Polar bears are really important in the Arctic ecosystem because they’re a top predator. And top predators indicate the health of the entire ecosystem. They represent what’s going on in the broader ecosystem and any changes that are happening in the links below them can cascade up to the polar bears. They are also very important to indigenous people in the Arctic who live alongside them. They have a deep cultural importance to them.

Photo by Kt Miller

Is there any hope? Can the polar bears survive climate change?

There is definitely hope. We have the tools right now to ensure that there is a future for polar bears. If nothing changes, it’s going to be very unlikely to see polar bears across large areas where we find them right now. But with changes in the way we use energy and how we generate energy, reducing fossil fuel emissions, there is very much still hope for polar bears to keep that essential sea ice habitat and to persist across the Arctic. I’m hopeful because we know what we need to do. We know that if we act, we’re going to see more polar bears in more places for longer.

I think getting to talk to many different people who are so interested in this challenge we’re facing as well also gives me hope. Talking to kids and to young people who are so motivated to understand what they can do and how we can ensure polar bears will be around for future generations, is also really inspiring to me. I get the sense that younger people are really dealing with this challenge they’re seeing and they demand that action is taken. There is this good sense of global awareness and global appetite, to deal with these problems right now instead of knocking them down the line. It’s really inspiring.

Photo by Kt Miller

Why are you so fascinated by polar bears and why did you choose to work with them?

I come from Ireland, an area that is not typically associated with polar bears – we barely get snow in winter. For me, seeing a species that is so well adapted to such an unfamiliar environment that feels so challenging, is something that just constantly fascinates me. I love learning more about them every day and figuring out what makes them tick and how they survive.

I’ve always been interested in the different ways that animals deal with different environments and polar bears are a pretty spectacular example of a species that has not only adapted to deal with this pretty tough environment, but they thrive when given the chance to persist there.

The first time I got to see polar bears was up in Manitoba, outside Churchill. This is where polar bears come onto lands waiting for that sea ice to freeze. I found it really interesting because you had this large white bear against this colourful autumnal tundra scene of all these browns and reds and oranges. This slightly dirty animal that looks somewhat out of place on the land. And then as it got colder, the snow came in. You just started to see that this looks like their environment.

It really stuck with me seeing this change from an animal that was hanging out in the willows and just kind of biding its time to then seeing them become more active. Seeing the ice start to form on the bay as the polar bears were waiting for their chance to get back out there. It was fascinating seeing them look more like the kind of Arctic predator I had seen in documentaries and in pictures.

Photo by Kt Miller

Why is it important to share scientific information and studies to the public about polar bears?

I think it’s really important for the public to have the knowledge about what is happening right now with polar bears and particularly what the future could look like if we don’t take any action. To give people the information they need to make informed choices in their daily lives, but also give people the information they need to ask for change of all different levels. Encouraging people to look for change from their representatives, from their civic leaders and really give them a chance to take action to ensure that polar bears are going to be around in the future.