YAKUTSK, Russia -- Thirty years ago, the road out from the village of Mai was flat. So were the fields around it, enough that local people used to play football on them.
But today, the road and fields around this town in the remote Siberian region of Yakutia, are strangely warped, an expanse of wavy ground and weird bubble-like mounds, that a drive over will bounce passengers out of their seats.
"This plot of land was very flat. In 1994, we played football, volleyball on it," Petr Yefremov, a local scientist who grew up in the village, told ABC News. "And you see, in that time, it's fallen like that."
The odd ground around the village is a sign of how in Siberia climate change is literally re-shaping the landscape, as rapidly warming temperatures start to alter what has long been a given in much of Russia's vast hinterland: that the ground is frozen.
Around two-thirds of Russia is covered by permafrost -- permanently frozen ground that never thaws, even during summers. It runs from just below the surface of much of Siberia for sometimes thousands of meters underground, kept frozen by the region's fierce colds.
But Siberia is warming and faster than almost anywhere else on Earth. Russia's average annual temperatures are currently rising two and a half times faster than the global average, according to Russian government data.
In Yakutia, the vast region where Mai is located, the warming is causing permafrost to start thawing. As it does, swamps and lakes are mushrooming around the region, as well as the strange landscapes like that around the village.
"The changes are noticeable," Pavel Konstatinov, head of the laboratory at the Melnikov Permafrost Institute in Yakutia's capital Yakutsk, about 3,000 miles from Moscow, told ABC News.
Stretching down from the Arctic, Yakutia would be larger than most countries if it was independent and is one of the coldest inhabited places on Earth, with winter temperatures routinely reaching below -70 Fahrenheit.
But Yakutia's average temperatures have risen by around 2 to 3 degrees Celsius in the past 40 years, according to local scientists. Like much of the Arctic, it is already well ahead of the 1.5 degrees Celsius that scientists have said the earth's temperature must not breach to avoid already catastrophic climate change.
Yakutia is seeing milder winters -- though still bitterly cold -- and in summer increasingly extreme heat, according to Russian government meteorological data. For the past four years, it has suffered record drought and heatwaves, which this summer contributed to colossal wildfires, some of the biggest ever anywhere in recorded history.
"Since the start of the 1980s, it has very sharply increased and the average annual air temperature for five years has jumped up 2, 3 degrees and until now stands at that level," said Konstantinov.
Yefremov, also a scientist at the Permafrost Institute, has studied permafrost for three decades. He and a team from the institute have sunk temperature monitors several meters into the permafrost near Mai.
Yefremov said that when the team first took measurements in the mid-1990s, the frozen soil's temperature 10 meters below ground was around -3. Now, it is closer to -1, he said.
"You see already how much it has fallen. Within 30 years, it's fallen from -3 to -1 degrees," he told ABC News during a visit to the monitors in August.
As the permafrost melts, it retreats further beneath the surface. In places like Mai, the receding ice leaves hollows underground. Over time, the top layer of earth begins to fall in, leaving little valleys that create the strange, uneven mounds. From above, the files look almost like giant scales. Eventually, the mounds all fall in together to form large pits that usually become lakes.
The land affected becomes largely useless for agriculture or building.
The amount of thawing in Yakutia varies drastically from place to place, depending on other ground conditions. It is far faster in areas where the permafrost is mixed with unfrozen ground and where there is water and some human activities.
Vladimir Romanovsky, a professor of geophysics at the University of Alaska Fairbanks, said that there was not yet "massive thawing" of permafrost but that we are now crossing the threshold into it.
"Ten or 20 years from now, that will be a different picture," he told ABC News. "If the trajectory will continue the same— we will have massive thawing of permafrost in warmer, discontinuous permafrost zone."
"Discontinuous" permafrost refers to areas where it is mixed with stretches of unfrozen land, unlike parts of the Arctic where the permafrost stretches as an unbroken mass.
Romanovsky said in Alaska, where conditions are somewhat different to Yakutia, he estimated around 50% of permafrost in the state's interior had begun to show signs of thawing in the past five years.
Scientists at Yakutia's Permafrost Institute this year estimated as much of 40% of Yakutia's territory is at risk of "dangerous" melting. Permafrost Konstantinov said some projections suggested even in moderate scenarios, a third to a quarter of southern Yakutia's permafrost would melt by the end of the century.
Some scientists worry that it also poses a profound threat for the rest of the world. The frozen soil holds hundreds of billions of tons of greenhouse gases, like methane and CO2, which are released as it slowly thaws.
The fear is that as the thawing unlocks more of the gases, they will further warm the planet, in turn triggering more melting. The amount of gases held in the permafrost dwarf those already put into the atmosphere by humans, and the fear of a cataclysmic feedback loop has led some scientists to call Siberia's melting permafrost a possible "methane time bomb."
Scientists caution there is still insufficient evidence to know how much melting greenhouse gas could be released by melting permafrost, but most experts believe it is a concern.
In Russia, the shifting ground is already posing enormous consequences, putting at risk roads, buildings and infrastructure across Siberia.
When frozen, permafrost is as hard as concrete and so most buildings in Yakutsk are constructed without foundations.
For that reason in Yakutsk, most buildings sit on stilts that raise them about a meter off the ground. Otherwise, heat from the buildings would thaw the permafrost beneath them, essentially turning their foundations into sand and causing them to subside.
Some older buildings in Yakutsk give a preview of what happens when the permafrost melts under them.
On a central street, one block is slowly collapsing. Huge cracks started appearing in the walls around five years ago. Local authorities declared the building unsafe for habitation a few years ago. Residents said and some of them had already been re-settled, but others remained, unable to find anywhere else to go.
Fedor Markov lives and works in a studio in one of the building's upper floors. He is a sculptor of miniatures made from mammoth tusks, fragments of which are widely found across Yakutia, where the permafrost sometimes preserves Ice Age creatures almost entirely intact. Markov's studio has large cracks in its walls and ceiling, including a gaping hole in its plaster, he said was caused by the building subsiding.
"The house is shaking," said Markov.
In another neighborhood further out of the city, residents have had to abandon a group of older barracks buildings. One building has a huge crack running to the roof, splitting the structure almost in half.
Russia's government has estimated the damage from the melting ground could cost tens of billions of dollars and there are increasing calls for action to mitigate the effects.
“Yakutia is already not like Yakutia,” Markov said. "In general, nature was excellent in my childhood. Summer was summer, winter was winter. Even though it was strong frosts, the people all the same could put up with it. Now we're starting to get scared," he said.