Lord Stern said the world had to act now or face huge economic woes
The government is being misled on the impact of climate change by relying on "unhelpful" economic models, the former UK chief scientific advisor has warned.
Professor Sir David King said the 2006 Stern Review underestimated the true economic cost of tackling the problem.
No model had predicted the current downturn, and none could cope with the scale of problems the world could face due to climate change, said Prof King.
Other experts have previously said the review underestimated the costs.
Prof King, who is now director of the Smith School of Enterprise and the Environment, said he questioned the value of what he described as the "simple models" in the review.
Such models are used when the government undertakes the cost-benefit exercises needed when a policy impacts on the environment.
Prof King said those developed by Lord Stern and his team were misleading and underestimated the environmental impact of projects such as building a third runway at Heathrow airport, in London.
He said that was because economic models were based on steady growth and did not fully take into account the costs of the catastrophic events likely to arise as a result of climate change, said BBC Science correspondent Pallab Ghosh.
Focusing on such economic models could lead to poor investments by government and businesses, he said.
The Stern Review said the world had to act now on climate change or face devastating economic consequences.
Sir Nicholas Stern, a former World Bank chief economist, said at worst the estimates of damage could rise to 20% of GDP or more.
But taking immediate steps could limit the damage to the world economy to 1% of total gross domestic product (GDP), he said.
He argued that spending large sums of money on measures to reduce carbon emissions would bring dividends on a huge scale.
The report was enthusiastically backed by the UK government, with then prime minister Tony Blair calling it "the most important report on the future ever published by this government".
But some academic experts said although they were convinced human-induced climate change was real and action was needed, the economics were flawed.
Prof King said there was little point in trying to predict the exact costs of events such as rising populations, rising sea levels and the drop in available land, changes in rainfall patterns and increased desertification, and the resulting large-scale migration.
He told BBC Radio Four's Today programme it was more important to have teams of scientists predicting the impact, and experts such as engineers working out solutions.
"We need to map out a future world that is a safer place for our grandchildren," he said.
In response, Dr Simon Dietz, deputy director of the Grantham Research Institute on Climate Change and the Environment and a member of the former Stern Review team, said: "Economic models of the impact of climate change, like scientific models of climate change, have both strengths and limitations.
He added. "As Nicholas Stern has highlighted, it has become apparent that the risks and potential costs of the impacts of climate change are even greater than we originally recognised."
"Future modelling will take that into account," he said.