Leading article: A Tale of Two Cities

Two multinational conclaves will make decisions on Friday that will test journalistic hyperbole. In Brussels, the European Union summit may decide the fate of the eurozone and therefore the quality of life of our children. But the decisions made by the 195 nations of the world at the United Nations climate-change summit in Durban, South Africa, on the same day could make an even bigger difference to the quality of life of our children's children.

The Brussels summit could make the difference between plunging Europe into depression and a return to the kind of growth experienced since 1945. The significant decisions are likely to be made in Paris tomorrow by Angela Merkel, the German Chancellor, and Nicolas Sarkozy, the French President, but formally they will be made by all the EU leaders on Friday.

The narrow focus of British commentary is on the domestic problems that this will present to David Cameron, who has promised his Eurosceptic party that he would hold a referendum on proposed treaty changes. That is part of a wider problem, which is that the response to the euro crisis seems to involve technocrats suspending democracy for the greater good. The appointment of unelected prime ministers in Greece and Italy did not look good, although their governments command majorities in elected parliaments. But the search for devices to avoid referendums in Ireland and elsewhere hardly helps the EU's claim to democratic legitimacy. Nothing could be more damaging to Mr Sarkozy's grand talk of "refounding Europe" than its being seen as a conspiracy of elites against peoples. But one other item of business on Friday will be Croatia's accession treaty, providing for it to join the EU, subject to a referendum, in 2013. The EU is still something that more people want to join than to leave.

The paradox of Brussels, of course, is that the summit is trying to get Europe back to the kind of economic growth that threatens the sustainability of human life. Important though it is for our next 20 years, the decisions made – or avoided – at Durban this week are even more important for the next 100. The caravan of UN climate-change conferences has, since Rio in 1992, stopped in a different city each year (last year was Cancun, next is Qatar), some of which have been more important (Kyoto 1997, Copenhagen 2009) than others. Durban could still be important, or it could be another stop at which all the hard choices are put off for another year.

Despite Mr Cameron's protestations, just before and just after last year's election, that a time of austerity was precisely the time to redouble green efforts, public opinion and much of the media are less and less seized of the urgency. The recession coincided with the emails scandal at the University of East Anglia, weakening acceptance of the science of climate change. Last weekend it was reported that Steve Hilton, the Prime Minister's adviser, told officials at the Department of Energy and Climate Change: "I'm not sure I believe in it." He makes the mistake of thinking that it is a matter of belief rather than of observation and (uncertain) prediction. In his Autumn Statement last week, George Osborne said: "We are not going to save the planet by shutting down our steel mills, aluminium smelters and paper manufacturers." The Opposition, led by a former climate-change spokesman, offers little resistance to this retreat from the rhetoric of "the greenest government ever".

This worrying trend is likely to be reflected in many other governments around the world. The best we can hope for from Durban is that Europe can afford to fall back a little from its forward green position, while the internal forces in Chinese politics continue to play themselves out. China's growing confidence as an economic superpower, its problems with its own pollution and its state power mean that it is more likely to engage with emissions control than at Copenhagen two years ago.

For all that Brussels poses a challenge to Mr Cameron, Durban poses an even greater one. With two of Mr Cameron's closest advisers, Mr Hilton and Mr Osborne, pushing the wrong way on climate change, we have to hope that the third, Samantha Cameron, will still urge her husband to remain green. Incidentally, the Prime Minister should beware the power of metaphor. In the recent photographs of her family in the Downing Street kitchen, Samantha is opening a tub of Lurpak Spreadable. At Durban, Mr Cameron has to show that, on climate change, he is not the soft alternative.