The case of Russian scientists trapped in their remote Arctic base by a group of inquisitive yet hungry polar bears does not come as a surprise. By late summer, Arctic sea ice is at a minimum and polar bears are effectively landlocked in coastal areas eagerly awaiting the return of ice during the autumn freeze and the chance to hunt seals again.
The Arctic summer is also the time of year when scientific activities are at their maximum, with bases operating at capacity and fieldwork operations at full flow, particularly in tundra and coastal regions. Polar bears are hungriest when scientists are busiest – “encounters” are inevitable.
Researchers working in the Arctic, particularly in and around the Arctic Ocean and its coastal seas, usually have to undergo some type of polar bear encounter training before embarking on fieldwork. This inevitably involves familiarisation with a large calibre hunting rifle and getting practice on a shooting range. Most Arctic settlements and scientific bases have a designated area for target practice and this can be accompanied by a short course on polar bear awareness.
A rifle is a “must have” and should be kept close to hand when out in the field. However, it is usually the last line of defence. A team of researchers in the field are likely to be equipped with flares and flare pistols – the latter equipped with special “flash-bang” rounds, aimed at scaring off inquisitive bears. Warning shots with a rifle should also work in deterring a bear, but equally the start-up of a noisy snowmobile engine should have the same effect.
The best advice is to pay attention to your surroundings and stay alert. This may seem obvious when operating in the vicinity of one of the world’s largest predators, but it is very easy for scientists to become absorbed with the task in hand. A team of scientists huddled around a broken instrument or focused on a rare plant will not be aware of an approaching bear.
Operating from scientific research ships carries its own risks. While the ship itself provides security, people operating on sea ice need protection. Surprisingly, visibility on sea ice is often restricted by the presence of ice ridges. These are formed when sheets of ice press up against one another and broken chunks of ice may extend up to three meters above the ice floe. The ridges serve as excellent cover for bears, who use them as hunting corridors, relying on their keen sense of smell to search out prey. For this reason, teams operating on sea ice usually have one team member designated to “ride shotgun”. Pump action shotguns equipped with shells fitted with solid lead slugs are commonly issued on Canadian icebreakers.
In the past, trapping and hunting were the biggest threat to polar bears and some populations were decimated as a result. However numbers have stabilised at around 20,000 to 25,000 since an international conservation agreement was signed in the 1970s – though polar bears are still officially classified as vulnerable.
These days, the biggest threats are climate change and pollution. As these marine animals are long-lived – a 15-20 year life span is not uncommon in the wild – they accumulate a variety of industrial chemicals that enter Arctic foodwebs through the atmosphere and ocean currents that flow northwards.
Legacy pollutants such as polychlorinated biphenyls (PCBs) and the pesticide DDT may have largely been banned, but they still linger in the environment. When I carry out fieldwork in the Arctic, it’s these sorts of chemicals I’m looking for. The pollutants “cycle” between air, soil and sea, eventually accumulating in snow, ice and marine sediments. Once present in seawater and sea ice they are picked up by tiny algae and plankton, which are eaten by fish, and then bigger fish, and so on. At each stage the concentration of these chemicals increases, until they reach astonishingly high levels in polar bears which sit at the top of the food chain.
Concern has grown recently about newer pollutants such as halogenated flame retardants and organofluorine chemicals used in the production of “non-stick” pots and pans. These chemicals interfere with the immune and hormonal systems of polar bears, and they may even be weakening their penis bones.
The effect of climate change, which is most pronounced in the Arctic, is to accelerate spring melt and delay winter freeze, meaning that bears remain landlocked for longer periods of time during the summer. This increases the risk of summer starvation and this, alongside the “co-stress” provided by a changing cocktail of contaminants, provides an existential threat to the polar bear.
This brings us back to the poor Russian scientists holed up in their base. Bears will adapt and seek out new food sources during their summer wait. Hunger and starvation may make them bold and more persistent in their quest for food and is only likely to increase the frequency of human-bear encounters.
Crispin Halsall receives funding from the UK's Natural Environment Research Council (NERC).
Authors: The Conversation