UN warns permafrost is melting

abc/A United Nations report says the world's permafrost is beginning to thaw, bringing with it the threat of a big increase in global warming by 2100.
Permafrost is a deep layer of frozen soil covering about a quarter of landmass in the northern hemisphere, and is thought to contain twice the amount of carbon already in the atmosphere.

A global temperature increase of 3°C means a 6°C increase in the Arctic, resulting in anywhere between 30 to 85 per cent loss of near-surface permafrost. Such widespread permafrost degradation will permanently change local hydrology, increasing the frequency of fire and erosion disturbances.
Damage to critical infrastructure, such as buildings and roads, will incur significant social and economic costs.
If the permafrost thaws, the organic matter will thaw and decay, potentially releasing large amounts of CO2 and methane into the atmosphere.
Thawing permafrost could emit 43 to 135 Gt of CO2 equivalent by 2100 and 246 to 415 Gt of CO2 equivalent by 2200.
UN report into permafrost thaw

An accelerating melt would free vast amounts of carbon dioxide and methane which has been trapped in organic matter in the subsoil, often for thousands of years.
In the report released at climate talks in Qatar, the UN Environment Program warned that the thaw could accelerate global warming.
The report says that warming permafrost could release the equivalent of between 43 and 135 billion tonnes of carbon dioxide, the main greenhouse gas, by 2100, up to 39 per cent of annual emissions from human sources.
Andy Pitman, director of the ARC Centre of Excellence in Climate Systems Science at the University of New South Wales, says the thaw could also release large amounts of methane.
"Permafrost stores carbon dioxide, but it also has lots of little microbes in it and lots of organic matter," he said.
"And when that organic matter isn't frozen any more, it gets broken down by microbes in the soil and under certain circumstances that breakdown process releases a lot of methane."
Charles Miller is the principal investigator for NASA's Carbon in Arctic Reservoirs Vulnerability Experiment.

The melting of the permafrost is no surprise to the locals who live in the town of Inuvik, about 200 kilometres north of the Arctic Circle in Canada's north-west.
Mayor Floyd Roland spoke to AM about the impact the changing climate is having on his village:

We're in a zone that is permafrost rich, as we call it, and we've had to adapt our construction techniques up here to avoid causing any melting and slumping of permafrost areas - we've noticed an increase in the last number of years.
We've been dealing with permafrost conditions, both the immediate building of the community, the infrastructure as well remediation as things start to change, the seasons start to change and you have to adapt for that when it comes to our runways, our roadways.
The permafrost was more stable - our seasons have definitely changed up here. When I grew up as a young boy here our winter season was coming from middle of September for example the rivers would start to freeze.
And we'd have much colder winters where nowadays it's sometimes middle of October and we don't get the extreme cold that we normally did.

'Canary in the coalmine'

Dr Miller says that in the short term, methane releases have a far greater impact on global temperatures than carbon dioxide.
"We're looking to see whether or not the impacts of climate change will cause the mobilisation of this stored carbon into dynamic carbon cycling which means it would be available in the atmosphere for photosynthetic uptake, and whether or not this carbon as it is released comes in the form of carbon dioxide or methane," he said.
"On a per molecule basis, methane is 75 times stronger than carbon dioxide over a 20 year time span."
He told the ABC's AM program that a thaw in parts of the northern hemisphere could provide also provide insight into the impacts of climate change worldwide.
"It's expected that climate change will impact the Arctic earliest. It's anticipated that climate change in the Arctic will be more dynamic than it would be in many other parts of the world," he said.
"And the ecosystems in the Arctic are so heavily adapted to the harsh conditions that exist there that the changes that are already occurring are happening faster than ecosystems can adapt.
"This is really a case of the canary in the coalmine where we might be able to find early detection of some things that would have larger, perhaps even global scale impact."