Introduction

The polar regions are crucial for the global environment in many ways. The Arctic, Subarctic and Antarctic regions contain much of the world's vast wilderness areas. They have profound affects on global climate. And they are significant bellwether regions. De-spite their remoteness from large population centres, the polar regions are already deeply affected by global environmental problems, including the long range transport of pollutants such as organochlorines and heavy metals, ozone depletion and global cli-mate change.

Rapid changes in polar climate are likely to have dramatic global repercussions. Burning boreal forests and degraded permafrost will release millions of tonnes of greenhouse gases into the atmosphere. Changes in polar ocean currents may cause unpredictable fluctuations in global weather patterns, especially in the North Atlantic. And melting ice sheets may contribute to sea level rise - directly in the case of Greenland, and indirectly, through the weakening of the Western Antarctic ice sheet, in the case of Antarctica.

In 1990, the United Nations' affiliated Intergovernmental Panel on Climate Change, released a landmark report concluding that:

• Levels of the greenhouse gas carbon dioxide have increased by 25 percent over the last century, and methane levels by 100 percent.
• Global average temperatures have increased by 0.5 degrees Celsius during the same time period.
• If fossil fuel consumption and deforestation continues as projected, greenhouse gases levels will reach double pre-industrial levels by 2030-2050. [1]

In 1995, the IPCC approved its second scientific assessment, concluding that "the balance of evidence suggests a discernible human influence on global climate ... the observed warming trend is unlikely to be entirely natural in origin". [2] The internationally respected chair of the IPCC, Dr. Bert Bolin, was even more direct in a recent speech: "There is no longer a question that human activity is leading to climate change". [3]

Climate scientists have long predicted that greenhouse gases will cause the most rapid and dramatic climate change in polar regions. This backgrounder examines the observed and projected climate changes in the Arctic and Subarctic polar regions and the profound affects these changes have begun to create in the North.