What Are the Causes of the Melting Polar Ice Caps?

Melting polar ice has become an icon of global warming and climate change.

Images of melting polar ice, drowning polar bears and receding glaciers have become iconic of the struggle with climate change brought on by global warming. Melting ice is thought to be a threat to arctic life, indigenous people and low-lying coastal cities.

Features

Carbon dioxide is only a small component of our atmosphere, representing just a few hundred parts per million; however, it has major effects. A greenhouse gas, it allows sunlight to enter our atmosphere but prevents it from escaping, causing temperatures to rise.

History

As reported in "Time Magazine", at the height of the last ice age, the planet's atmosphere contained about 180 parts per million of carbon dioxide. By the time the ice age ended, carbon dioxide levels had reached 280 parts per million. In the last hundred years, carbon dioxide levels rose to 381 parts per million.

Function

This added carbon dioxide is thought to contribute to an increase in average temperatures. As reported in "National Geographic," the Arctic Climate Impact Assessment conducted between 2000 and 2004 discovered that the average temperatures in arctic regions of Canada, Alaska and Russia have increased four to seven degrees.

Significance

Warmer temperatures cause polar ice to melt at a faster rate than normal. For example, as Eric Rignot of the Jet Propulsion Laboratory in Pasadena and Pannir Kanagaratnam of the University of Kansas told Time Magazine, Greenland lost 53 cubic miles of ice in 2006, compared to 22 cubic miles in 1996.

Considerations

Shiny polar ice reflects 90 percent of the sunlight that strikes it back into space. Liquid water, on the other hand, retains 90 percent of the energy it receives. The more energy it absorbs, the hotter it gets. The hotter the water, the faster the ice melts. The melting ice frees a relatively warm layer of Atlantic water, which, as Ruth Curry from Woods Hole Oceanographic Institute told "Time," rises into the atmosphere and releases more heat.

References

• "Time Magazine"; Global Warming Heats Up; Jeffrey Kluger; 2006
• "National Geographic News"; Artic Melting Fast; Brian Handwerk; November, 2004