THE massive release of methane and other gases from the Arctic will make it tougher to meet human greenhouse gas cuts, but the scale of the problem will still be determined by how much fossil fuel is burned by humans in coming decades, scientists say.

A UN report issued at climate change negotiations in Doha, Qatar, found that human greenhouse gas emissions were triggering the Arctic thaw.

''The picture isn't completely dire though - this isn't an all-or-nothing scenario,'' said Ben Abbott, a scientist working on permafrost melt at the University of Alaska.

Tipping point ... the melting earth. Photo: Ross Duncan

''The take home message to me from those numbers is that we can still make a difference if we are able to limit fossil fuel carbon emissions.''

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The amount of greenhouse gases that are likely to be released from the Arctic melt this century is still uncertain. The UN report looked at a range of scenarios that would put between 43 billion and 135 billion tonnes of extra carbon dioxide from the Arctic into the air this century.

''Based on these ranges, you would have potentially anywhere between 3.8 per cent and 12.3 per cent more carbon being put into the atmosphere, on top of all the other sources that are emitted,'' said Pep Canadell, a CSIRO scientist and executive director of the Global Carbon Project, which tallies up CO2 emissions.

Using the most conservative figures, Dr Canadell calculated that, if the cost of abating these extra emissions was set according to the present Australian price of $23 a tonne, the process of trying to negate the Arctic emissions would be about $35 billion.

On present trends, the UN goal of trying to hold global warming to two degrees, by limiting the amount of carbon dioxide in the atmosphere to 450 parts per million, will be missed by a wide margin.

The federal government's official position at the Doha negotiations is to support the development of a global response to climate change, consistent with Australia's national interest, to hold temperature rises to two degrees.

Asked if it would take account of the new rates of permafrost emissions in its planned emissions cuts, a spokeswoman for the Climate Change Minister, Greg Combet, said the Climate Change Authority would take it into account when it starts operating in 2014.

''The Climate Change Authority, whose board includes significant scientific expertise in the Chief Scientist and Professor David Karoly, is required to have regard to environmental effectiveness in providing its advice on emissions caps and carbon budgets,'' the spokeswoman said.

''The government's climate changes policies are focused on being environmentally effective, economically responsible and socially fair.''

The government intends to cut emissions, with the help of the carbon price, to 5 per cent below their levels in the year 2000 over the next eight years. Its 2020 target would only be made more ambitious if other developed countries such as the US, Canada and Europe commit to emissions cuts on the same level, as part of a legally-binding global agreement.

It would only move to emissions cuts of 25 per cent in the event that there is ''comprehensive global action capable of stabilising atmospheric greenhouse gas concentrations at 450 parts per million or lower.''

The opposition's position is the same as the government's minimum commitment - to cut Australia's greenhouse emissions to 5 per cent below their 2000 levels by the year 2020. It proposed to do this by abolishing the carbon price and the Climate Change Authority, paying companies to release less CO2, and by changing some farming and land management practices to pack soils with extra carbon.

"The thawing of the permafrost is extremely concerning and highlights the importance of achieving real action on reducing emissions,'' said the coalition's climate spokesman, Greg Hunt.

Asked if the coalition would be in favour of deeper cuts in light of new scientific developments, he said it would not.

''The Coalition remains committed to the 5 per cent reduction by 2020 and our support for conditional targets remains unchanged."

The Greens want much deeper cuts, of 25 to 40 per cent by 2020, to set Australia up for being ''carbon neutral'' by the year 2050, roughly in line with the trajectory outlined by the International Energy Agency.

''The extra methane emissions from permafrost is a terrifying outcome,'' said the Greens leader, Senator Christine Milne.