Polar Bear Environmental Effects

While it once might have seemed impossible that the sea ice in the Arctic would ever cease to exist, today the trends in melting sea ice are conclusive, and the leading cause of polar bears being at risk. In the past thirty years, mean world surface temperatures have increased 0.2°C per decade. However, in some parts of the Arctic, temperatures have increased ten times the rate (Hansen et al, 2006). Since the late 1970s there have been major reductions in summer sea ice extent, decreases in the extent and age of multiyear ice and thickness, and increases in length of the summer melt period. September 2007 set a new record minimum that was 23% lower than the previous 2005 record. Winter sea ice has also started to decline, but at a slower rate
POPs are wildly dispersed in the environment, posing significant health threats to wildlife, as well as humans. Examples of pollutants would be PCBs, which are used in plastics, and dioxins, which are used in pulp and paper bleaching. Polar bears are particularly vulnerable to the harmful effects of POPs for two key reasons. First, POPs tend to concentrate in the Arctic because of a process of long-range air transport and disposition known as the grasshopper effect. Airborne pollutants are carried on air currents where they condense, deposit, and then re-evaporate to be carried further north. Cold temperatures prevent re-evaporation of these POPs, leaving the Arctic on the receiving end of this cycle (Plotkin, 2007). Secondly, polar bears are on the top of the food chain, which makes them vulnerable to the effects of biomagnification. Concentrations of POPs increase with every step up the food chain and are many times higher than those in their prey. The Stockholm Convention, an international legally binding agreement on persistent organic pollutants, requires that environmental release of twelve POPs be reduced or eliminated. Canada is among the one-hundred-and forty-four countries that are party to this treaty, as of 2004. However, newer pollutants such as polybrominated biphenyl ethers, which researchers have detected
A study was conducted to analyze temporal variation in polar bear distribution on the sea ice in Hudson Bay to determine how home range size and location may be responding to the change in sea ice conditions. Collars were deployed on solitary adult females greater than the age of five, and female with cubs. DS collars were deployed on forty-six females in 1990-1998, and GPS collars on ninety-five females in 2004-2012. For DS collars, 3,781 locations were analysed, and for GPS collars 63,714 locations were analysed (McCall, Derocher, & Lunn,