Permafrost

In his new book, A World Without Ice, geophysicist Henry Pollack explains the complex influences that Earth's ice has had on human survival, and that population growth and industrialization are now having on the survival of Earth's ice. Following is an excerpt.

By Henry Pollack

Just as the international financial system surprised the world with a major collapse in 2008, the global climate system, with its human component, is equally capable of serious surprises.

Lurking in the shadows of climate change is the possibility that the accelerations we now observe in the climate system are portends of approaching tipping points.

While politicians around the world debate how to reduce human-caused greenhouse gas emissions, scientists are making some unsettling discoveries about another developing greenhouse gas problem: nature’s own emissions.

A study published this week shows that the amount of carbon locked in the Arctic permafrost is more than double previous estimates. Additionally, other research shows that the permafrost is thawing, meaning this enormous amount of carbon could be released into the atmosphere as the greenhouse gases carbon dioxide and methane.

The thawing of the permafrost is especially dangerous because it could cause a domino effect of more warming that, for now, cannot be checked by human engineering or policy.

"We now estimate the deposits contain over 1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere", said Dr. Charles Tarnocai, Agriculture and Agri-Food Canada, Ottawa, and lead author of the study, published in Global Biogeochemical Cycles.

As long as permafrost is frozen, the carbon in the soil is locked up.

But when it thaws, the carbon becomes exposed, and microbes called methanogens break down the carbon and release methane, a greenhouse gas that is 20 times more effective at trapping heat than carbon dioxide.