Dr Hansen, who served as an adviser to Al Gore on his controversial documentary The Inconvenient Truth, said: “There is remarkable inconsistency between the scientific story and public story.
“The science has become stronger and stronger over the past five years while the public perception is has gone in completely the other direction. That is not an accident.
“There is a very concerted effort by people who would prefer to see business to continue as usual. They have been winning the public debate with the help of tremendous resources. Who knows how the East Anglia email fiasco came about?
“There is a huge gap between the public’s understanding of the situation and the scientific understanding. If the public doesn’t understand, it is not going to happen. Political leaders are not independent of public opinion.”
His comments come as recent surveys have revealed that public support for tackling climate change has declined dramatically in recent years. The British Social Attitudes survey published last year revealed that just 22 per cent said they are now in favour of green taxes compared to 31 per cent in 2000. Over a third said many claims about environmental threats were “exaggerated” compared to 24 per cent in 2000.
A recent BBC poll found that 25% of British adults did not think global warming was happening.
Environmental campaigners suffered a major blow in 2009 when emails stolen from computers at the University of East Anglia were leaked and were hailed by critics as evidence of scientists attempting to suppress evidence that contradicted the idea of man-made climate change.
An inquiry into the scandal failed to find any evidence of malpractice by the scientists and a review of the science also found it to be sound, although the findings were met with claims of bias from sceptics.
Dr Hansen, who has published hundreds of papers on climate change and has become a high-profile activist in recent years, now fears that without a dramatic change in public opinion, future generations will inherit a world where global warming is out of control.
In a lecture he is due to deliver after receiving the Edinburgh Medal, he will claim that today’s adults have a moral obligation to cut fossil fuel use to secure the world for their children and grandchildren.
He said: “We know that the planet is out of balance – more energy is going in than going out. That is one of the findings that has become clear in the past five years.
“If we wanted to restore the energy balance this century, we would need to reduce emissions by six per cent a year, starting this year. If you wait another 10 years you would have to reduce emissions by 15% a year. That would be almost impossible.
“Our parents honestly did not know what the consequences of continued development and reliance on fossil fuels as an energy source. We can no longer claim that as the science is now clear. We can only pretend we don’t know.”
Dr Hansen will argue that by placing a global levy on all fossil fuels, including coal and gas, it would encourage a move towards alternative forms of energy.
In a paper due to be published last this year with other leading environmental scientists and economists, he will argue that there needs to be a rapid transition to clean energy combined with widespread reforestation to restore the planet’s energy balance.
He will also condemn governments for “ineffectual” policies on climate change.
Dr Benny Peiser, director of sceptical think tank The Global Warming Policy Foundation, said governments and the public had “more urgent problems to deal with” than tackling climate change.
He said: “People have become bored by some of the rhetoric from the green movement as they have other things to worry about.
“In reality the backlash against climate change has very little to do with the sceptics. We will take credit for instilling some debate but it is mainly an economic issue. Climate change is not seen as being urgent any more.
“James Hensen has been making predictions about climate change since the 1980s. When people are comparing what is happening now to those predictions, they can see they fail to match up.”