Tony Blair wants a 60% cut in greenhouse gas emissions by 2050. But it?s not clear how Britain can meet those targets. Credit: © Punchstock

Whatever other effects it has, climate change is producing some unlikely bedfellows. Right-wing parties are brandishing their green credentials, and some environmentalists have emerged as advocates of nuclear power. Politicians are turning somersaults in their efforts to present the right face to disparate camps: yes, they say, we support economic growth and oil exploration, as well as wind power, a hydrogen economy and carbon sequestration. Whether you are an industrialist or an ecowarrior, we're right behind you.

The Bush administration treads this tightrope with brazen ambiguity. "Global climate change is a serious long-term issue," the US president told Nature recently (see ""Head to head"":http://www.nature.com/news/specials/uselection), only to add that "considerable uncertainty remains about the effect of natural fluctuations on climate and the future impacts climate change will have on our natural environment". So is there cause for alarm or not? The United States, he says, should "mitigate the growth of greenhouse-gas emissions", but not, apparently, in line with even the timid constraints of the Kyoto Protocol.

In a speech on 14 September, the British prime minister Tony Blair seemed to be more forthright. Climate change, he said, is "the world's greatest environmental challenge," and "timely action can avert disaster". But happily, this dark cloud for industry has a silver lining, as averting climate change presents "immense business opportunities".

You cannot discuss climate change with an expectation of zero risk.

Perhaps it is unfair to criticize politicians for such mixed messages. After all, they do not have the luxury of the black-and-white arguments that lobbyists serve up. Sooner or later, however, we are going to have to face the bad news, which no politician wants to acknowledge: there really is no sweetener to the problem of climate change.

Immense opportunity?

Blair is not wrong to see opportunities in climate change: the goal of reducing fossil-fuel emissions could be a tremendous stimulus for technology. We want cheaper, more efficient photovoltaic cells, better thermoelectric materials for harvesting geothermal energy, artificial photosynthesis and photocatalytic splitting of water, and more compact and convenient fuel cells. We need better insulators and we need ways to capture carbon from its gaseous forms.

But these are opportunities only in the sense that the global AIDS epidemic offers opportunities for biomedical research. They are opportunities we would be happier living without. And as with HIV, we don't know yet whether we'll find the answers in time.

Another problem with Blair's position is that his climate-change targets for Britain are so ambitious that some commentators have greeted them with derision. He wants a 20% reduction in carbon dioxide emissions by 2010 and no less than a 60% reduction by 2050. As Blair himself admits, "This implies a massive change in the way [Britain] produces and uses energy." The Times newspaper, for example, responded by saying, "Blair has no way of meeting these targets. There is no reputable scientist unbribed by government subsidy who regards them as remotely feasible."

More to the point, the Times lambasts Blair for failing to make any promises about what, to many, seems the obvious solution: nuclear power.

All the British government will say on this is that it does "not rule out the possibility that at some point in the future new nuclear build might be necessary if we are to meet our carbon targets".

That is surely a coy way to skirt around what may be the key issue. One can argue endlessly about the cost and efficacy of wind turbines and other renewable sources, and about the savings achievable by better efficiencies in energy use, but it's incredibly difficult to see how the numbers will ever add up to a 60% carbon dioxide cut in 45 years. Moreover, wind and solar energy are hampered by being intermittent: their 'capacity factor' (the ratio of total annual power output to potential output if operating always at full power) is typically around 25%, compared with 90% for nuclear power.

Running out of time

Perhaps even more pertinently, we may not have five decades to play with. That, at least, is the view of James Lovelock, the independent scientist lionized by environmentalists for his idea that our planet operates as an interconnected biogeophysical system, which he calls Gaia. "We do not have 50 years," Lovelock says. "We have no time to experiment with visionary energy sources; civilization is in imminent danger and has to use nuclear, the one safe, available energy source, now or suffer the pain soon to be inflicted on our outraged planet."

Lovelock has ruffled feathers with this so-called environmental heresy, but at least no one can accuse him of shying away from a difficult choice. Tony Blair knows that in Britain nuclear power is still deeply unpopular, and it certainly has a dire economic record. The existing UK power plants alone soak up around £12 billion (US$21.5 billion) in subsidies; the bill for revitalizing the nuclear industry would be breathtaking.

There is less squeamishness in the United States, and George W. Bush (but not John Kerry) has declared an intention to expand nuclear power generation. In Japan, nuclear plants account for around one-third of the country's total electricity production; in France, three-quarters of the total power is nuclear and the country has one of the cheapest electricity supplies in Europe.

New reactor designs should make them safer and more economical, and might use excess heat to generate hydrogen fuel from water. All this seems to imply that nuclear power, if well managed, can work. No one can deny that the waste-disposal problem remains. But there is no reason to believe it is intractable, and indeed this is arguably another technological 'opportunity'.

Still, a proper debate about the virtues of nuclear power must acknowledge its vices. The legal action that the UK government faces from the European Union over sloppy accounting for the waste stored at the Sellafield plant is a timely reminder of the difficulties of ensuring that nuclear material remains in the right hands; the links between civil power and weapons technology have never been severed. Mining of uranium has been messy and exploitative in the past. And the impending twentieth anniversary of the Chernobyl disaster might make the coming year a tricky time to conduct a dispassionate debate about nuclear energy.

But it has to happen. Tony Blair is surely right to say that you cannot remove nuclear power from the agenda "if you are serious about the issue of climate change". Neither can you discuss that agenda with an expectation of zero risk. Whether or not Lovelock is right about the timescales, there will be dangers implicit in whatever course of action we take.