Since that book was published, the effects global climate change have become too evident for Lomborg’s calmness to seem reasonable any more. Today, only a handful of serious scientists doubt that unless we do something decisive to limit our pollution of the natural world – by curbing population growth, reducing carbon emissions or building homes, cars and appliances that are more energy efficient – we will soon pass a “point of no return” after which environmental safeguards will be useless because we will have lost our ability to affect the climate. Al Gore has made this point repeatedly, but even if he hadn’t there is an overwhelming body of research to support his wariness.

Despite embarrassments like the “Climategate” emails – which suggest that climate researchers at the University of East Anglia tinkered with their data – there are thousands of studies which establish, beyond reasonable doubt, how much we have fouled the atmosphere. One striking measure is the amount of carbon dioxide in the air. Before the Industrial Revolution, the level was about 280 parts per million, but today that figure has risen to 390 – the highest level in 15 million years. But while most researchers can agree that we face a genuine dilemma, there seems to be little consensus on what should happen next. As the failures of Copenhagen showed, many bureaucrats and politicians believe that halting progress on the environment is the best we can reasonably hope for, especially in light of the developmental challenges which so many parts of the world currently face.

There are, however, other reasons why the green movement has failed to deliver on its promises at the highest levels and these have nothing to do with development or scientific evidence. In the current issue of The Nation, a distinguished left-leaning US periodical, British journalist Johann Hari takes a hard look at green activism in the UnitedStates and finds hypocrisy almost everywhere. Several prominent groups have even struck up partnerships with the polluters they were meant to monitor. Two years ago, for example, the Sierra Club, after a mild acknowledgement of the obvious conflict of interest, agreed to endorse a new line of “green” Clorox bleach, in return for a percentage of the sales. The board promised the Club’s members it would analyse the bleach, and establish the truth of the advertising claims, but this was never done.

Christine MacDonald, a former activist at Conservation International and author of Green Inc, a damning account of the movement’s loss of idealism, told Hari that “Not only do the largest [US] conservation groups take money from companies deeply implicated in environmental crimes; they have become something like satellite PR offices for the corporations that support them.” Consequently, last year when the Center for Biological Diversity (CBD) urged the US Environmental Protection Agency (EPA) to ensure the Clean Air Act be used to impose carbon dioxide levels of 350 ppm (a figure supported by many climate change experts) the Sierra Club vociferously opposed the initiative and even threatened to intervene in the EPA’s defence if the CBD took legal action to force the agency to comply.

Hari also complains that the US Senate’s attitude to environmental legislation is deeply compromised by generous campaign donations from the Oil and Coal lobby. This manipulation of the system is arguably more consequential since “The US climate bills are long-term plans: they lock us into a woefully inadequate schedule of carbon cuts all the way to 2050. So when green groups cheer them on, they are giving their approval to a path to destruction – and calling it progress.” Hari’s scepticism also extends to schemes like the much-touted Reducing Emissions from Deforestation and Forest Degradation (REDD) programme which has received so much attention in this region.

Thirteen years ago in Bolivia a coalition between The Nature Conservancy and what Hari calls “three big-time corporate polluters – BP, Pacificorp and American Electric Power (AEP)” created a protected area of the forest called the Noel Kempff Climate Action Project. This initiative set aside 3.9 million acres of tropical forest, promised to end logging in the area and provide guarantees that the forest would remain standing. Early estimates said the would keep “55 million tons of CO2 locked out of the air – which would, in time, justify their pumping an extra 55 million tons into the air from their coal and oil operations.” But far from achieving these targets, a subsequent investigation by Greenpeace found that “logging companies [in the protected area] had simply picked up their machinery and moved to the next rainforest over… In fact, one major logging organization took the money it was paid by the project to quit and used it to cut down another part of the forest.” Shamefacedly, the project “had to admit it had saved 5.8 million tons or less – a tenth of the amount it had originally claimed. Greenpeace says even this is a huge overestimate.”

Obviously the hypocrisy of some environmental groups, however shameful, should not be allowed to tarnish the importance of their cause, nor obscure the success of inspired initiatives like 350.org – a worldwide coalition which calls for far more extensive protections than those proposed at Copenhagen. In fact, even at this late stage of the deepening environmental crisis, there is still room for optimism. In his recent bestseller, Hot, Flat and Crowded, New York Times columnist Thomas Friedman has shown how quickly government-backed research and development, tax incentives, new subsidies and energy markets could spur huge advances in energy efficiency and the production of cheap, clean, renewable energy.

On the other hand, if the green movement fails to pursue its mission effectively, and succumbs to corporate and political compromises, measures to slow further global change are likely to fail. Political will is likely to be the key to these different outcomes, and that will only occur when an engaged public learns a measured scepticism towards the political half-measures, and compromised activism that are meant to be tackling this crucial challenge on our behalf.