Anthropogenic impacts on the habitat and habits of polar bears

When browsing websites looking for information on climate change, people are likely to come across images of polar bears in different situations: from specimens crossing the icy wilderness of the Arctic to some distressing ones of starving adults looking for unusual food for their diet. For years, these majestic giants with their gentle faces have become icons for campaigns to raise awareness of the consequences of anthropogenic activities in seemingly remote ecosystems.   

The Arctic is the area around the North Pole; it includes parts of Russia, the United States, Canada, Greenland, Iceland, Sweden, Norway and Finland. It is the only place in the world where there are polar bears and the progressive decrease of their ice cover over the past 30 years has modified their habitat and, consequently, their lifestyle. These animals depend on the delicate planetary balance; that is why they have been facing difficulties in carrying out essential activities such as reproduction and hunting for decades. If we continue in this direction, with a continuous increase in global temperatures due to the use of fossil fuels, we would be facing a drastic transformation of the dynamics that exist in this ecosystem and the extinction of two thirds of the polar bears by 2050.   

International Polar Bear Day, founded by Polar Bear International, takes place every February 27. Its aim is to raise awareness of the consequences of climate change on the conservation status of this species. The date coincides with the period when the mothers and their cubs take refuge in their dens and is used as an opportunity to invite the various stakeholders to take measures to reduce greenhouse gas emissions.  

Scientists have identified different subpopulations (19 so far) of polar bears distributed in four ecoregions, spread over the countries that have access to the circumpolar area. These ecoregions vary in terms of ice cover distribution and behavioral patterns of each subpopulation. To understand the threats they have in common, the Circumpolar Action Plan (CAP), a ten-year cooperative plan among jurisdictions whose territories are home to polar bear populations (United States, Canada, Greenland and Russia), identified ten human-caused risks. These include greenhouse gas emissions, oil spills, poaching, pollution, shipping, disease and parasites.   

But how do the different impacts translate into the current reality for polar bears?  

The Special Report on the Ocean and Cryosphere in a Changing Climate (IPCC) reveals that there is a relationship between the seasonality, thickness and location of snow and ice cover and the area in which polar bears are able to find food. As a result, changes have been seen in their diet, such as resorting to whale carcasses and other unusual prey. As the planet warms, there are shorter hunting windows and longer fasting periods, and they must travel farther to find food, which means higher energy consumption. The problem is that a reduction in their home ranges means that the different polar bear subpopulations will become increasingly isolated from each other. Also, a reduced average weight is a risk for future generations, as it decreases the chance that the number of individuals within a litter of cubs will survive.  

For now, we can count on the fact that there are regions less affected than others and polar bear communities that are resisting; a number of them have demonstrated a capacity to adapt and that climate change does not affect some ecoregions in the same way as others. But we don't know for how much longer. In recent years, there have been calls to diversify the way in which we communicate about a phenomenon as multifaceted as global warming. However, the changes in the habits and welfare of the polar bear remain a valid expression to illustrate the anthropogenic impacts on the planet. 

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