In just over six months' time, officials from the world's nations will meet under the auspices of the United Nations to try again to complete the task that was beyond them in Copenhagen in 2009, to establish a legally binding treaty to curb global warming. It is hard to see why it could go any better this time — if anything, the global economic slump and the failure to pass cap-and-trade legislation in the United States will make it even harder. A report published this week in the United States does an excellent job of probing the reasons for this stalemate, and shines light on some uncomfortable truths. It should be essential reading for anyone with a passing interest in the climate-change debate.

The report, Climate Shift: Clear Vision for the Next Decade of Public Debate, is written by Matthew Nisbet, a professor of communication and environmental science at American University in Washington DC. It focuses on the situation in the United States, and particularly its political failure to pass comprehensive climate legislation. But the points it makes go far beyond Capitol Hill. And it effectively dismantles three of the most common reasons given by those who have tried, and failed, to garner widespread support for policies to restrict greenhouse gases.

First — the failure of the US Senate to pass a cap-and-trade bill in 2010 cannot be blamed directly on the financial lobbying muscle of the conservative movement and its allies in industry. In 2009, the report says, although a network of prominent opponents of cap and trade, including ExxonMobil and Koch Industries, spent a total of US$272 million lobbying policy-makers, environmental groups in favour of cap and trade mobilized $229 million from companies such as General Electric and other supporters to lobby for environmental issues. Indeed, the effort to pass cap and trade, Nisbet notes, “may have been the best-financed political cause in American history”.

Second — most of the mainstream media coverage of climate change gets it right. During 2009 and 2010, Nisbet writes, around nine out of ten news and opinion articles in The New York Times, The Washington Post and CNN's online site reflected the consensus scientific position. The Wall Street Journal regularly presented the opposite view in its opinion pages, but eight out of ten news items still backed the science.

Third — conservative media outlets such as Fox News and controversies such as the coverage of e-mails hacked from the University of East Anglia in the United Kingdom have a minimal impact on public attitudes to climate change, because such influences tend to only reinforce the views of those who already hold doubts.

The failure of cap and trade in the United States, Nisbet concludes, was not down to poor communication, but was due to framing the issue of greenhouse-gas emissions as a problem that could be solved by a specific policy. More useful, he says, would be to present climate change as an issue that needs to be addressed at many levels, similar to public health or poverty. Those, of course, are far from ideal models — but we live in far from ideal times.