This year, celebrate International Polar Bear Day by learning more about these amazing animals from a scientist who has studied them for decades.

 Scientist Thor Larsen with a polar bear cub. A happy moment for the polar bear researcher. ©Thor S. Larsen

Thor S. Larsen is a pioneer in polar bear research. He began his academic career in 1965 at the Norwegian Polar Institute. From there, he became a member of the IUCN (International Union for Conservation of Nature) Polar Bear Specialist Group from 1968 to 1985. Working with other scientists in the Specialist Group, he helped initiate the international Agreement on the Conservation of Polar Bears, signed in 1973. 

After visiting the Arctic for over 50 years, he still describes his feelings for the region as a “never-ending love story.”

Larissa Beumer, a Greenpeace Germany Arctic campaigner, spoke with him about his work:

What was it like to study polar bears in 1965?

At that time, we didn’t know anything about polar bears! We didn’t know if all polar bears in the Arctic belonged to the same population or if there were distinct subpopulations, how many there were, or anything about their migration patterns or their population biology – for example, their reproduction or mortality rates.

At the first scientific meeting in Fairbanks, concerns were expressed that polar bears were over-hunted in many areas. But no country was able to provide any reliable data on numbers of polar bears anywhere in the Arctic. The estimates of world population numbers ranged somewhere between 5,000 and 19,000 polar bears, even numbers as high as 25,000 were mentioned. But in reality, all these numbers were just “guestimates” rather than estimates based upon sound scientific data.

So back in 1967, we started the systematic polar bear research in Svalbard: we captured them, marked them with ear tags, took various samples and undertook several surveys trying to count them from ships and airplanes. We also talked to trappers to gather information from them.

The fieldwork back then was very different from today. For 15 years, we only went to Kong Karls Land on skis, without any motorized vehicles. Once, I stayed on Edgeoya for 16 months doing fieldwork only using dog sledges. In 1973 we travelled with the Sirius patrol in Greenland along the East coast to study polar bears there. On all those field trips, we would always stay in very small cabins, only about four to five square meters, and went skiing every day. You were completely by yourself, surrounded by pure wilderness.

Scientists climb an iceberg in the Arctic to study polar bears. ©Thor S. LarsenImage courtesy of Thor S. Larsen

Why did you want to study polar bears?

We knew nothing about them, so it was a real scientific challenge. And I was very fascinated by the Arctic. I had been there to do scientific work on birds. You fall in love when you work with one of the most beautiful and exciting animals on Earth. I was extremely fortunate to be able to do this.

©Thor S. LarsenImage courtesy of Thor S. Larsen

How many polar bears have you seen in your life?

I have seen more than 2,000 bears. Then I stopped counting. But when I see one today, it is as beautiful as it was the very first time.

What was your most memorable encounter with a polar bear?

Oh, I couldn’t tell… But maybe it was the times when we did maternity den surveys on skis. You observe the female with her small cubs leaving the den for the first time after having spent several months without eating, only giving birth and nurturing the newborn cubs. The cubs would start playing and discovering this new world – she looks at you, you look at them… Those moments were magical.

You get very humble when you work in the Arctic for so many years, and you really respect nature.

Polar bear cubs resting after a tiring day. ©Thor S. LarsenImage courtesy of Thor S. Larsen

How did the 1973 IUCN (International Union for Conservation of Nature) agreement work to protect polar bears?

The IUCN created a Polar Bear Specialist Group in 1965. They sent personal invitations to polar bear experts in the Soviet Union, the USA, Canada, Denmark and Norway. I was lucky to be one of them.

The group was small, with only two representatives from each of the five Arctic states and a small secretariat. We decided to have closed sessions – only a Russian-English translator from IUCN’s staff remained in the room. The presentations and discussions were frank and open after the doors had been closed. We challenged each other about research findings and management advice.

The first meeting of the Specialist Group was held in 1968. After that meeting it was clear that there was a need for an international convention or agreement for polar bear conservation, and we pursued this further in the next meetings in 1970 and 1972.

As an international NGO(non-governmental organization), IUCN was not authorized to implement an international agreement. But with the help of our research we could prepare the draft agreement between the five Arctic states.

Five Arctic countries signed the Agreement on the Conservation of Polar Bears in 1973, and in 1976 it entered into force. The agreement banned the killing of polar bears in general, irrespective of national and international laws. But there were exceptions. One was traditional hunting by indigenous communities that were dependent on it for their livelihood.

To date, it is referred to as a prime example of international cooperation. I am glad that I could contribute to that process and that it came into force before it was too late – before polar populations were at critically low levels because of over-harvest.

What are the biggest threats to polar bears today?

When the agreement was signed in 1973, we thought that polar bears were now protected forever. But today they are facing completely different challenges than hunting.

The sea ice is retreating and thinning, making it increasingly difficult for polar bears to hunt seals. This affects their body conditions. When bears get stranded on land in summer when the sea ice retreats northwards, they can survive without any food for about 6 months, but then their condition is not the best and they have to use their fat reserves. Some of these bears are pregnant females. When the cubs are born around New Year they usually only weigh 500g. When they leave the maternity den in spring, they weigh about 10kg. The females have to raise them to this weight from their own body weight. If they don’t get enough food during the summer months to accumulate sufficient fat to be able to feed their cubs after birth, they might abort or reabsorb the fetus and will thus not produce any offspring in such years. In that way, the retreating ice also affects their reproduction.

The loss of sea ice also has an impact on the maternity denning areas. Popular denning areas for polar bear females are islands such as Wrangel Island in Russia or Hopen and Kong Karls Land in Svalbard. However, if the sea ice extent does not reach to these islands in autumn, the females don’t go there for denning.

When I did research on Kong Karls Land between 1972 and 1985, there were usually about 40-50 maternity dens each spring and the number of dens increased each year. That was a result of the total protection of polar bears in Svalbard. In spring 2009, after a winter with rather normal ice conditions, my colleagues found 25 dens. In autumn 2010, the waters around Kong Karls Land were ice-free. In the following spring, they found only 13 dens. The following autumn, the waters were again ice-free, and only five dens were found in spring 2012. We’re observing the same picture in other areas as well. A friend of mine who works on Wrangel Island told me that in the 1970s, there were usually 300-400 dens each year. In the recent years, they had only about 30-40 dens. If this should become a regular pattern, it means that there is very low recruitment in the populations. And that is a very bad sign.

Another big problem is the heavy trans-boundary pollution with toxic contaminants such as persistent organic pollutants and heavy metals. They accumulate in the food chain, so polar bears are especially vulnerable because they are on top of the food chain. Scientists suspect that this also affects their reproduction, but we don’t have any proof yet. But we know that for example the pollution in Svalbard’s polar bears is very high.

Polar bears on ice. ©Thor S. LarsenImage courtesy of Thor S. Larsen

What is the status of polar bear populations today?

According to information that the Specialist Group published in 2012, many polar bear sub-populations are declining. A few are stable, but for half of the Arctic data are deficient. Only one population is said to be increasing, but the data is from 2000. In general, we need better data to make reliable estimates.

Do you think polar bears will be able to adapt to climate change?

I don’t know. There is lots of debate about how old polar bears are as a species. At the moment, we think they are about 600,000 years old. There were lots of variations in climate in those 600,000 years, including periods where the ice had retreated considerably. So maybe they will be able to adopt their life style, but we can only guess here. It also depends on the speed of changes. And on other negative impacts such as pollution, that stress the populations in addition to climate change.

Pollution and climate change are overarching international problems that we can only solve on the international level. We need to make sure to tackle these problems, but also to keep all other additional negative impacts such as illegal hunting as low as possible. Polar bear cubs and yearlings are particularly sensitive to environmental changes. Therefore, infrastructure developments and transport activities should be prohibited in and around denning areas and there should be regular seasonal den surveys and monitoring of reproduction in the populations.

Polar bears on ice. ©Thor S. LarsenImage courtesy of Thor S. Larsen

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Larissa Beumer is an Arctic campaigner with Greenpeace Germany. She interviewed Thor S. Larsen in 2015.

A version of this interview was originally published by Greenpeace Germany.