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Polar Bears and Climate Change
Polar bears are among the species most vulnerable to climate change. If Arctic sea ice starts to break up earlier than normal in the spring because of climate change, polar bears will have reduced access to hunting and breeding grounds. Female polar bears will not be able to hunt enough food to sustain them through the summer months. With lower body weights, the mothers will have a hard time successfully nursing their cubs. In Canada, the southernmost polar bear populations are already experiencing declines in cub survival because of these factors.
The far-reaching effects of climate change are already evident in the Arctic, where the rate of warming is at least twice as fast as anywhere else on Earth. Arctic ice is shrinking at an alarming rate, the average thickness dropping nearly 40 per cent in the past three decades.
What is Climate Change?
Climate change is a long-term shift in environmental conditions occurring worldwide. For thousands of years, the Earth's climate has hardly changed at all. Temperatures, rainfall, the length of seasons, and other environmental factors have remained just right for humans, animals, and plants. This stability is thanks to the greenhouse effect.
Just as the glass of a greenhouse keeps the sun's warmth inside, an invisible blanket of "greenhouse gases" - consisting mainly of water vapour, carbon dioxide, nitrous oxide, and methane - trap solar heat in the Earth's atmosphere. Without these gases, the heat of the sun would escape into space, and the average temperature on our planet would plunge by 33°C - from 15°C to -18°C.
Average global temperatures have risen significantly since the start of the Industrial Revolution in the early 1700s. The 1990s was the warmest decade in 1,000 years. In some parts of Canada, temperatures could rise by 5 to 10°C. While that might not seem like much of a leap, the average temperature during the last ice age was only five degrees cooler than today. Scientists fear that the Earth could become too warm, resulting in climatic changes greater than humans have ever witnessed.
As temperatures rise, polar ice caps, glaciers, and sea ice will melt faster than before, raising global sea levels, causing higher tides, and damaging coastlines with floods and erosion. Extreme weather events, such as hurricanes, thunderstorms, tornadoes, and heat waves, will happen more often and more severely.
How Is Climate Change Affecting Wildlife?
Climate change is already having an impact on all kinds of wildlife. Species worldwide are shifting their ranges, migrating sooner, and bearing young earlier than in the past. American robins and red-winged blackbirds frequently arrive on their breeding grounds weeks before they once did. Edith's checkerspot butterfly has moved its range northward and up into mountains as temperatures heat up further south.
In the past, climate change occurred so slowly that wild plants and animals had time to adjust. Today, shifts in temperature, seasons, and weather are happening so fast that wildlife has little chance to adapt. Instincts developed over thousands of years are becoming useless. Key habitat elements - food, water, shelter, and space - are declining or disappearing.
Global warming is also blamed for the widespread decline of amphibians, including Costa Rica's golden toad, now feared extinct. Coral reefs worldwide are dying off because of unusually warm ocean temperatures.
The most dramatic changes of all are taking place in the High Arctic, which is heating up faster than anywhere else. In fact, Northerners are watching in disbelief as sea ice shrinks and pulls back from the coast; new species of birds like robins and barn swallows, settle in; unfamiliar plants, like white spruce and dwarf birch, spread over the tundra; and salmon are caught for the first time.
Across this country, governments, industries, schools, communities, and individuals are taking action to curb climate change and address its impacts. Their efforts include improving the management of forests and wetlands; supporting climate change and atmospheric research; increasing energy efficiency in buildings and automobiles; and developing renewable energy sources, such as wind turbines and solar power, and fuel cell technology.
How can you help conserve the polar bear?
A great way to help is to learn all about this magnificent mammal. The Space for Species Web site is your window on the polar bear's world. Here you can monitor the movements and habitats of this and other migratory species from beyond the Earth's atmosphere. For more on the challenges facing the polar bear and efforts to protect its population, visit the Species at Risk in Canada Web site. No matter where you live in Canada, you can help prevent long-range impacts on the polar bear through the following action projects:
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How can you help?
Climate Change Educational Package
To commemorate National Wildlife Week 2002, CWF's educational experts have created an action and awareness unit on climate change. What sets the package apart from other classroom resources on this subject is that, rather than highlighting human concerns, it stresses the impacts of warmer temperatures, rising sea levels, calamitous weather events, and other phenomena on wildlife and habitat. It addresses the challenges facing species, like whooping cranes, polar bears, and coho salmon, as well as ecosystems, like grasslands, forests, and shorelines. It encourages young people to ask questions and seek solutions to protect wildlife habitat from this ecological crisis.
Consisting of both a printed package and an online learning module, the unit is thematically linked to the Common Framework of Science Learning Outcomes, K to 12. Through an abundance of classroom activities, students learn the importance of climatic health, discover what it means to be climate friendly, investigate declining biodiversity in relation to climate change, develop a sense of responsible stewardship towards the planet's ecosystems, and much more. Visit our WILD Education Web site to download a copy of this educational package.
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About the Polar Bear
Long-distance Impacts The polar bear may live far away from cities, smokestacks, highways, and croplands. Yet it carries in its huge body high levels of contaminants, such as PCBs, DDT, mercury, and dioxins - substances rarely if ever used in Canada's North. Contaminants flow into Arctic waters on ocean, river, and atmospheric currents from all over Europe, Africa, Asia, and North America. They work their way from the bottom to the top of the aquatic food web until they concentrate in the fatty tissues of predators, like polar bears, orcas, and Inuit people. These dangerous substances can cause major problems, including cancer, tumours, reproductive failure, and birth defects. As if contaminants weren't enough, another long-distance threat now faces polar bears - climate change. The burning of fossil fuels worldwide is increasing the amount of carbon dioxide, nitrous oxide, methane, and other greenhouse gases in the atmosphere. Like a blanket, these gases trap the heat of the sun near the Earth, not only raising global temperatures but also changing climate worldwide. Scientists predict that average global temperatures could increase by 1.5 to 4.5°C in the next century. With winter temperatures in the Arctic rising by 5 to 10°C, the North could experience the greatest climate changes of all: increasing snowfall; warmer, deeper seas; losses in the expanse and thickness of ice cover; and restrictions in the movements of polar bears, muskoxen, and other animals that migrate over ice.
Who Rules the ice? Bill Guerin or Polar Bears? Click Here! |
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IN PERIL
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BEAR & CUB![[pic]](images/bear003.jpg)
ASLEEP