Polar Bears and Climate Change

Did you know that polar bears are at high risk of population decline and future extinction in our warming world? Dr. Steven Amstrup, a Research Wildlife Biologist with the United States Geological Survey, discussed the status of the iconic marine mammal in the lecture, “Polar Bear: Climate Change Sentinel.” The lecture was part of the Columbus Zoo and Aquarium’s Conservation Lecture Series. Dr. Amstrup works at the Alaska Science Center in Anchorage and has conducted research on polar bears for the past 28 years. He was part of the research group that prepared reports used in the listing of the polar bear as a threatened species.

Polar bears are the apex predator of the Arctic. They are closely tied to the sea ice, depending on it for mate selection, breeding, caring for young, and most importantly, hunting ringed and bearded seals. Pregnant females come on land in the fall and den for the entire winter to give birth and care for their cubs. The other bears continue to hunt on the sea-ice year round.

Studies have shown that polar bears prefer medium to thick sea ice over the shallower waters of the continental shelf. However, as Arctic sea ice has retreated in past years, bears are forced to travel out further (and over much deeper and less productive water) to hunt from the ice edge. In the West Hudson Bay area, females are coming ashore up to three weeks earlier and thus losing valuable time to feed before denning. In both cases this leads to decreased weight and a decreased survival rate of cubs and older individuals. Years of sea ice decline correlate with population decline in the Hudson Bay and Beaufort Sea areas, trends which are most likely consistent with other polar bear populations around the world.

Based on this data, researchers projected that as a result of global warming and sea ice decline, polar bear populations have a very high risk of extinction within the next century. One particular population in the Canadian archipelago may be able to survive through the end of the century, as the ice there is still thick and covering shallow water. Ice thinning in that area may open up increased hunting opportunities and support a larger population. However, if warming trends persist, this population will also eventually be at risk.

When asked how individuals could help polar bears, Amstrup spoke of immediate changes to reduce our carbon footprint. While large scale action by governments and corporations is certainly necessary, it is worthwhile to remember that changing our individual habits (and encouraging others to do the same) can make a difference.

A study of polar bears and their response to climate change aligns with the Life Science and the Science in Personal and Social Perspectives content standards of the National Science Education Standards.

The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. Find science content standards in Chapter 6.

Resources

Polar Bears International
PBI is nonprofit organization dedicated to the worldwide conservation of the polar bear. Find background information and information about the bear’s listing as a threatened species.

 The Polar Bear Tracker
Follow the movements of polar bears throughout the Arctic. Use the real-time data to explore how global warming is affecting the bears.

Tracking Polar Bears
In this interactive activity adapted from the USGS Alaska Science Center, investigate the migration patterns of polar bears.

Polar Bears Change Diet
This radio broadcast from 2001 explains how polar bears have adjusted their diet due to the climate warming around Hudson Bay, Canada. The ringed seals that polar bears normally eat have been harder for polar bears to get to, due to disappearing ice. This has forced polar bears to begin eating harbor seals and bearded seals. The clip is 4 minutes and 15 seconds in length.

Polar Bears and Climate Change
This video from the World Wildlife Fund addresses the primary threat to polar bears in the Arctic today: global warming. Scientists monitor the effects of climate change on the large predator’s activities and range, study the bears’ physical condition, and explore why the melting of glaciers and reduction of sea ice in the Arctic region may ultimately have dire consequences for the polar bears.

Bearly Any Ice
This game is similar to tag that simulates the prey and predator relationship between polar bears and ringed seals. It demonstrates the drastic impact of global warming by linking the amount of sea ice and length of season of sea ice to the survival of the polar bear.

Science and the Polar Regions
Background information, lessons, resources, and standards alignment for a study of the polar regions.


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