After his forecast that global warming will cause sea levels to rise up to 25 metres this century and his urging of alternative fuels to coal, a cornerstone of Australia's booming trade industry with China, Professor Flannery has been branded an extremist in some sections of the country's media.

'I don't know whether there is a conspiracy or not,' he said, before heading to Europe and the US on a trip that will include 'trying to fit in' a meeting with Virgin tycoon Sir Richard. 'When you try to change something there will be a cost and you can be distracted by all that sort of stuff.'

His aim - to make climate change the big issue at the Australian election later this year - means Professor Flannery will require a thick skin for months to come.

'He's got a far greater profile than he had before and I think he will play a very prominent role in the election,' said Andrew Macintosh, deputy director of the Australia Institute, a left-leaning think-tank. 'He's trying to position himself as a key advocate for climate change policy, something on which he will take a quite robust position. And whenever he speaks people listen. That's something the conservatives, who have been so reluctant to take climate change seriously, don't want to hear.'

Professor Flannery, who is best known internationally for his best-selling books The Future Eaters, and more recently, The Weather Makers, makes no apology for his headline-grabbing warnings about our changing climate.

He warns it's an issue of human survival, and criticised this year's landmark report by the International Panel on Climate Change for being too moderate.

Rather than sea level rises of up to 59cm by 2100, Professor Flannery says up to 25 metres is more likely. He cites 'breathtaking' acceleration in the melting of the Arctic ice sheet, warning it could be gone within 15 years.

And if China continues its expansion of greenhouse gas emitting coal-fired power stations? 'China's water crisis will grow from being ominous to being totally catastrophic,' he said.

'The east coast will simply cease to exist. It's a gentle coastline supporting a large population and it will be under water. That may happen over centuries, but it would be the end for cities like Shanghai. And there would be half a billion refugees to deal with.'

Professor Flannery is one of many leading scientists who argue that developed nations need to adopt a 'war footing' to rapidly slash emissions of carbon dioxide and other greenhouse gases.

His support for replacing coal, and its huge CO2 emissions, with clean renewable energies has been a matter of public record for years.

He says 'geothermal' energy produced from hot rocks several kilometres underground has the potential to cover Australia's total electricity needs for a century. Two years ago, he bought about A$20,000 (HK$122,500) worth of shares in a company trying to perfect the technology.

But all that was before he became Australian of the Year during a period in which climate change had charged to the top of the domestic political agenda.

Professor Flannery's reassertion of those long-held views during a TV interview in January whipped up a storm.

Politicians from across the political spectrum accused him of wanting to close down Australia's biggest export industry, which earns A$25 billion annually from sales to countries such as China and employs more than 30,000 people.

Prime Minister John Howard said that kind of 'knee-jerk reaction' would devastate many communities.

'One part of their 'magnum opus' is to replace coal exports with such things as energies from hot rocks,' said Nationals Senator Barnaby Joyce of Professor Flannery and his green supporters. 'One could come up with some very clear suggestions as to where they could find them.'

One editorial in the right-wing newspaper The Australian labelled Professor Flannery a 'political gift' in the ruling conservative coalition's attempt to defeat the opposition Labor Party and win a fifth successive term. 'Professor Flannery is the sharp end of the political wedge,' said the newspaper. '[His] alarmist climate-change mantra will seduce Labor, dragging it too far from mainstream thinking and costing it electoral support.'

After refusing to ratify Kyoto and long being locked in the camp of climate change sceptics, the government is struggling to convince voters of its green credentials. By painting Professor Flannery as an alarmist who wants to wreck national living standards, the government is attempting to shift the climate debate to one of economic management.

Mr Macintosh said these tactics mirrored Mr Howard's strategy against Labor's pledge to save old-growth forests in Tasmania at the last election.

'The government converted a green issue into an economic issue, into a big job loss,' he said.

And it worked - Labor lost key seats in its traditional heartland. Although Professor Flannery aligns himself with no political party, recent events may have prompted a subtle change in his approach.

Development of clean coal - where the CO2 is captured - would be part of the solution, he said, and a rapid but controlled phasing-out of conventional coal was best. '[Otherwise] less reputable players will simply move in and take the trade, and you wouldn't get a chance to develop new technologies and alternatives.'

But the consequences of inaction are clear to him.

'The Earth is in a very similar position to someone who goes to a doctor and gets told they've got cancer and it's quite advanced,' said Professor Flannery. 'The question the patient asks is, 'How long have I got and what can I do about it? The sooner we start on a comprehensive course of treatment, the better the prognosis.'