Senator Fielding, who must vote soon on the Government's proposed emissions trading scheme, has returned from Washington sceptical about humanity's contribution to climate change.

"I think all of us have just accepted without question that carbon emissions are the problem and we need to address that," he said yesterday. It was necessary to consider an "alternative view" put forward by "credible scientists", he said.

Senator Fielding attended a conference on climate change last week hosted by the Heartland Institute of Chicago, which specialises in challenging scientific norms and conventions.

Its president, Joseph Bast, also believes the dangers of smoking are exaggerated as an excuse to tax tobacco.

Anti-smoking advocates "personally profit by exaggerating the health threats of smoking and winning passage of higher taxes and bans on smoking in public places", the institute's website says.

"The public health community's campaign to demonise smokers and all forms of tobacco is based on junk science."

Senator Fielding believes theories he heard at the conference, which linked solar flares to climate change, were plausible and the Government needed to convince him otherwise.

The Climate Change Minister, Penny Wong, who is due to have discussions with Senator Fielding this week, will arrange a meeting between the senator and Australian Government scientists if he requires it.

Senator Fielding said: "If the answer is, 'It's just rubbish' … well, I think that's not good enough."

Senator Wong's assistant minister, Greg Combet, told the Herald yesterday "the science is in" regarding the impact of carbon pollution on climate change but "Senator Fielding is entitled to gain as much advice and information as he can".