Award-winning researcher James Hansen says new president's rhetoric must be backed by action.

    Current approaches to deal with climate change are ineffectual, one of the world's top climate scientists said Thursday in a personal new year appeal to Barack Obama and his wife Michelle on the urgent need to tackle global warming.

    With less than three weeks to go until Obama's inauguration, Prof James Hansen, head of Nasa's Goddard Institute for Space Studies, asked the recently appointed White House science adviser Prof John Holdren to pass the missive directly to the president-elect.

    Obama spoke repeatedly during his campaign about the need to tackle climate change, and environmentalists fervently hope he will live up to his promises to pursue green policies.

    The letter, from Hansen and his wife Anniek, is a personal plea to the first couple. It begins: "We write to you as fellow parents concerned about the Earth that will be inherited by our children, grandchildren, and those yet to be born ... Jim has advised governments previously through regular channels. But urgency now dictates a personal appeal."

    In a covering letter to Holdren, Hansen explains that he wrote the letter a few weeks ago while in London. His wife had suffered a heart attack ("fortunately we were near a very good hospital") and while they waited for doctors to give the go-ahead to fly back to the US he decided to compose his petition to the new first family.

    Hansen has been one of the most prominent advocates of action to tackle climate change since he first spoke on the issue at congressional hearings in the 1980s. His testimony to the senate featured in Al Gore's film An Inconvenient Truth and he has received numerous honours for his work on the issue, including the WWF's top conservation award.

    Hansen wrote that there is a "profound disconnect" between public policy on climate change and the magnitude of the problem as described by the science. He praised Obama's campaign rhetoric about "a planet in peril", but said that how the new president responds in office will be crucial. The letter contains a wish list of three policy measures to tackle global warming.

    Hansen lambasts the current international approach of setting targets to be met through "cap and trade" schemes as not up to the task. "This approach is ineffectual and not commensurate with the climate threat. It could waste another decade, locking in disastrous consequences for our planet and humanity," the Hansens wrote.

    The letter will make uncomfortable reading for officials in 10 north-eastern and middle-Atlantic states whose carbon cap and trade mechanism - the Regional Greenhouse Gas Initiative - got under way today. The scheme is the first mandatory, market-based greenhouse gas reduction programme in the US and it aims to cut greenhouse gas emissions from the power sector by 10% by 2018.

    Hansen advocates a three-pronged attack on the climate problem - all measures he has promoted before. First, he wants a moratorium and phase-out of coal-fired power stations - which he calls "factories of death" - that do not incorporate carbon capture and storage.

    "Coal is responsible for as much atmospheric carbon dioxide as the other fossil fuels combined, and its reserves make coal even more important for the long run," the Hansens wrote.

    Second, he proposes a "carbon tax and 100% dividend": a mechanism for putting a price on carbon without raising money for government coffers. The idea is to tax carbon at source, then redistribute the revenue equally among taxpayers, so high carbon users are penalised while low carbon users are rewarded.

    Finally, Hansen wants a renewed research effort into so-called fourth generation nuclear plants, which can use nuclear waste as fuel. "In our opinion [fourth generation nuclear power] deserves your strong support, because it has the potential to help solve past problems with nuclear power: nuclear waste, the need to mine for nuclear fuel, and release of radioactive material."

    Hansen argues that the current emphasis on reduction targets combined with carbon trading schemes make it too easy for countries to wriggle out of their commitments. He cites the example of Japan's increasing coal use - the dirtiest fuel in terms of carbon emissions. To offset these increases in emissions Japan has bought credits from China through the clean development mechanism - an instrument set up by the Kyoto protocol - yet China's emissions have continued to increase rapidly. China has now overtaken the US as the biggest polluter in the world.

    "Nobody realistically expects that the large readily available pools of oil and gas will be left in the ground. Caps will not cause that to happen - caps only slow the rate at which the oil and gas are used. The only solution is to cut off the coal source," the Hansens wrote.