Permafrost exists all over the world, but Russia has the largest patches of it. Scientists estimate that permafrost covers more than 10 million square kilometers of Russia. A Russian scientist, Mikhail Sumgin first coined the term permafrost, or "vechnaya merzlota" (eternal frost), in the late 1920s.
But, now, less than a century later, scientists are worried about how permanent the permafrost really is.
Larry Smith, professor of geography at the University of California-Los Angeles, and colleagues compared satellite images of Siberia from the early 1970s to those taken in 2004. They found that the total area of lakes increased by more than 12 percent.
"If you just think of a deeply frozen landscape, when you first start to thaw it out, it's going to puddle up at the top," Smith says.
In southern Siberia, where the permafrost is more sporadic, lakes are actually disappearing at an equal rate, as the permafrost degrades and lake water seeps into the ground.
The effects on wildlife are profound. Birds in the south have to find new areas to raise their young, while small mammals, such as badgers, are now being seen in parts of the north for the first time.
Humans are also feeling the impact. Some people have had to leave their homes built upon permafrost as attempts are made to restabilize the structures.
Katie Walter is part of a joint U.S.-Russian team of scientists studying the lakes and has spent months at a time for the last four years in a small village north of Yakutsk, studying thawing lakes.
"If you just take the bus down the street or walk down the street even near the airport or in lots of parts of Yakutsk, old houses have sunk into the ground and the window panes are now under the surface of the ground," she says.
At the same time, traveling around Siberia has become more difficult as the window for travel has narrowed.
"The period when the ground is frozen is usually the best time to travel over the ground," Walter says. "But it's warming up, so there [are] fewer days of the year when you can travel over the frozen ground, because in the summer it becomes really marshy, and it's hard to travel in it."
And, Siberia's problems affect not only Siberians. Walters found that melting permafrost in Siberia is releasing five times the amount of methane than was previously thought. And methane is a particularly potent greenhouse gas -- it is considered 20 times more damaging as a greenhouse gas than carbon dioxide.
This means that Siberia is not just suffering from the consequences of global warming but is also actively contributing to it.
Walters has compared the melting of the Siberian permafrost to a time bomb waiting to go off. Until her team published a paper in the science magazine "Nature" last month, few scientists had an accurate picture of how much methane was being released. Current climate-change models have not yet been updated to predict how Siberian permafrost will affect climate in this century.
A Russian colleague of Walter's, Sergei Zimov, director of the Northeast Science Station in Chersky in Russia's Sakha Republic, is trying to fight the global trend on his own turf. He has built a wildlife park, bringing in caribou, horses, reindeer, bison, and moose, to restore a long-gone ecosystem and preserve the local permafrost.
"This place is called Pleistocene Park and so he's trying to bring the animals back in because when the animals move around they stomp the snow down and that keeps, that reduces the insulation above the frozen ground and that means that the winter cold can get into the ground and keep that permafrost cold," Walters says.
The Pleistocene era was the last phase of the Ice Age and occurred some 10,000 years ago. During that period, ice sheets repeatedly advanced and retreated.
In the meantime, residents of Yakutsk and nearby environments have noticed the warming trend around them. According to Walters, they fear that "if global warming is real" then where they live "is going to go under the sea."