What is Permafrost? Permafrost soil is soil at or below the freezing point of water (0 °C or 32 °F) for two or more years. Most permafrost is located in high latitudes in close proximity to the North and South poles, but alpine permafrost may exist at high altitudes in much lower latitudes. The extent of permafrost can vary as the climate changes. Today, approximately 20% of the Earth's land mass is covered by permafrost or glacial ice.

The problem is, this frozen ground contains large amounts of carbon-rich grass and animal bones. A new study warns, carbon that has been locked away for thousands of years could escape into the atmosphere if global warming thaws large patches of frozen ground in Alaska and Siberia as expected. Scientists calculate that about 500 gigatons (Gt) of carbon is locked away in permafrost. One gigaton is equal to one billion tons.

The researchers estimate that if global warming continues at its current pace, about 90 percent of the carbon in permafrost could be released. Most of it would go into the atmosphere as either carbon dioxide or methane, the researchers say.

THE FACTS

Approximately 20% of the Earth's land mass is covered by permafrost or glacial ice.