In Northern Alaska, people don’t need to be convinced about climate change because they see it happening all around them and literally under them — the very ground is changing.
Each year, the sea ice gets thinner and arrives later. The lack of shore ice that used to protect them from storms is leading to some villages being moved inland. Fish species from warmer waters, new birds and new insects, like spruce bark beetles, which kill trees, are appearing.
Houses are built on stilts, to avoid melting the permafrost, a layer of frozen earth that begins about two feet beneath the surface and goes down, in North Alaska, some 2,000 feet. Some of those houses are collapsing. Roads which needed resurfacing once a decade because of melting permafrost are now being resurfaced every year. So-called ‘drunken forests‘ are appearing as trees start to keel over.
The ground is changing, melting and it could be a preview of our worst climate nightmare.
Globally, permafrost covers an area the area of the United States and Canada minus Texas. It holds an estimated 400 gigatons of methane, one of the greenhouse gases that is hastening the earth’s warming. As the permafrost thaws — which it has begun to do — lakes can drain away and the thawed soil can release billions of tons of methane into the atmosphere.
About half of the world’s underground organic carbon is found in northern permafrost regions. This is more than double the amount of carbon in the atmosphere in the form of the greenhouse gases carbon dioxide and methane.
Now scientists are using new satellite methods to track changes.
Although permafrost cannot be directly measured from space, factors such as surface temperature, land cover and snow parameters, soil moisture and terrain changes can be captured by satellites.
A February conference about the satellite measurements produced a number of animations showing disconcerting changes in freezing patterns and surface temperature over the arctic over several years.
· You can watch the animations here.
You can also watch another animation, which zooms in on the seasonal deformation of a track of land on Alaska’s North Slope during the summers of 2010 and 2011. Watch the red shift that signals the transformation of frozen ground into squishy muck — a meltdown that then subsides several centimeters as summer turns to fall.
The thaw which the satellites are detecting is already evident on the ground. In an article for the Smithsonian Magazine, Bob Reiss met Inuit Milton Noongwook. He is shown a series of large wooden boxes set deep into permafrost to store frozen walrus meat — winter food. Noongwook pulled aside a door and in the dark below Reiss sees hunks of meat amid a sheen of frost. But it was also wet down there. “It’s melting,” Milton said. “It never used to do that. If it gets too warm, the food will spoil.”
Greenhouse gases from permafrost have only been measured as a factor in global warming in the last few years. Currently, the estimate is that they will contribute to making warming happen up to a third faster. But this is only, as one scientist calls it, “a seat-of-the-pants expert assessment.”
Since 1970, the Arctic has warmed at a rate twice as fast as the rest of the globe, due to polar amplification. There is some evidence that the speed of temperature increases there is causing rapid change in the permafrost. A 2010 study found methane emissions rising by a third in just five years.
The good news? According to recent modeling work, if global emissions are cut rapidly and deeply enough to meet the world’s stated target of limiting the average global temperature rise to 2C above pre-industrial levels, the majority of the world’s permafrost will remain frozen.