One of the world's foremost climate scientists has warned that vulnerable island states may need to consider evacuating their populations within a decade due to a much faster than anticipated melting of the world's ice sheets.

Michael Mann, director of the Earth System Science Center at Pennsylvania State University, said the latest evidence shows that models have underestimated the speed at which the Greenland and west Antarctic ice sheets will start to shrink.

Mann, who was part of the IPCC team awarded the Nobel peace prize in 2007, said it had been expected that island nations would have several decades to adapt to rising sea levels, but that evacuation may now be their only option.

His warning comes just weeks after the National Snow and Ice Data Centre in Boulder, Colorado disclosed that sea ice in the Arctic shrank a dramatic 18% this year on the previous record set in 2007 to a record low of 3.41m sq km.

"We know Arctic sea ice is declining faster than the models predict," Mann told the Guardian at the SXSW Eco conference in Austin, Texas. "When you look at the major Greenland and the west Antarctic ice sheets, which are critical from the standpoint of sea level rise, once they begin to melt we really start to see sea level rises accelerate.

"The models have typically predicted that will not happen for decades but the measurements that are coming in tell us it is already happening so once again we are decades ahead of schedule.

"Island nations that have considered the possibility of evacuation at some point, like Tuvalu, may have to be contending those sort of decisions within the matter of a decade or so."

Mann says the Pacific islands, which are only 4.6 metres above sea level at their highest point, are facing the imminent prospect of flooding, with salt water intrusion destroying fresh water supplies and increased erosion.

Suggesting evacuations would accelerate a change in public consciousness around the issue of climate change, he said: "Thousands of years of culture is at risk of disappearing as the populations of vulnerable island states have no place to go.

"For these people, current sea levels are already representative of dangerous anthropogenic interference because they will lose their world far before the rest of us suffer.

"I think it is an example, one of a number, where the impacts are playing out in real time. It is not an abstract prediction about the future or about far off exotic creatures like polar bears. We are talking about people potentially having to evacuate from places like Tvulu or the Arctic's Kivalina, another low lying island which is already feeling the detrimental impacts of sea level rise."

Mann, who is one of the primary targets for attacks by "climate deniers," said that there is still uncertainty about the speed of global warming as it is not clear what the impact of feedback mechanisms could be. In particular, he pointed to the release of methane that will come as the permafrost in the arctic melts.

"We know there is methane trapped and as it escapes into the atmosphere it accelerates the warming even further," he said. "But we don't know quite how much of it there is, but there is definitely the potential to lead to even greater warming than the models predict."

Mann said it was not only island states that were feeling the impacts of climate change and warned that the terrible drought and wildfires suffered by the US this year were just the precursor of far worse to come.

"If you look at the US, some of these things are unfolding ahead of schedule and we are already contending with climate change impacts that were once theoretical," he said.

"We predicted decades ago that this might eventually happen. We are watching them unfold and there are very real consequences to our economy and to our environment.

"The climate models tell us that what today are record breaking levels of heat will become a typical summer in a matter of 20-30 years if we carry on with business as usual. Not only will this become the new normal but we will have to change the scale because we will see heat and drought far worse than anything we have seen before."

The silver lining in all the bad news is that while the political system is gridlocked when it comes to confronting climate change, public attitudes are starting to change.

"It is going to take a little while to sink in," says Mann "but there is evidence of a dramatic shift in awareness and the public increasingly recognises climate change is real and if the public becomes convinced of this, they will demand action and they are connecting the dots because we are seeing climate change playing out in a very visible way.

"I think we are close to a potential tipping point in public consciousness and what will tip it, you never quite know, but another summer like the one we just witnessed we will see a dramatic shift in public pressure to do something about this problem."

One reason that attitudes are changing slowly, according to Mann, is that scientists are tending to be conservative in their forecasts out of fear that they will be attacked for overstating evidence.

He said the tactics of those who question climate change was not only to intimidate scientists already in the public arena, but also to warn off others from taking part in the public discourse.

But Mann believes the power of the Koch brothers and others in the fossil fuel lobby, whom he believes have been responsible for poisoning the whole climate change debate, is on the wane.

"I am optimistic," he says. "The forces of denial will not go down with a whimper and as the rhetoric becomes more heated and the attacks become more concerted, we see the last vestiges of a movement that is dying. The effort to deny the problem exists will have set us back decades but it is still possible to avoid breaching 450 parts of per million of CO2 if concerted action is taken."

While he is severely critical of those private business that are seeking to deny climate change exists, he said there were other businesses who were starting to wake up to the need to change behaviour.

"I personally don't believe captains of business are villains and who don't care about the legacy of the world, even though there are a few bad apples," he says. "Just look at the reinsurance industry where they face devastating losses if climate change moves.

"There are an increasing number of companies like Walmart which are ideologically conservative but have a real commitment to sustainability as they realise that as people become more concerned, they will reward companies that are part of the solution."

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