Poles, North and South

The North Pole and the South Pole are defined by the intersection of the Earth's rotation axis with its surface. In a broader sense, the poles encompass all land and ocean at the high latitudes, where ice, sea ice, and snow are perennial.

Ice and snow are important components of Earth's climate system and are particularly sensitive to local and global climate change. Changes in snow cover and sea ice have immediate effects on land and ocean heating, the strength of major ocean currents, terrestrial and marine ecosystems, [Page 2204]and human activities. As stated in the Fourth Assessment of the International Panel on Climate Change (IPCC), “Warming of the climate is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.” On this premise, the International Polar Year (IPY) was launched in March 2007, until March 2009. The program involves thousands of scientists from 63 nations, in more than 200 projects, to examine a wide range of physical, biological, and social research topics in the Arctic and Antarctic regions.

Unlike the South Pole, which lies on a continental land mass, the North Pole is located in the middle of the Arctic Ocean, surrounded by waters that are almost permanently covered with sea ice.

Continental ice sheets extend horizontally for hundreds to thousands of kilometers (km) and are 1 to 4 km in thickness. The two existing ice sheets over Greenland and Antarctica represent 3% of Earth's total surface area and 11% of its land surface. They contain some 32 million km3 (cubic kilometers) of ice, equivalent to about 70 meters of sea-level change. During winter, large sections of the Arctic Ocean and Southern Ocean freeze into patches of sea ice.