With Kyoto it was a case of all step together, or not at all. The negotiations of the protocol which set targets for greenhouse gas emissions for 2012 were bedevilled by the preoccupation that if any of the large polluters was not to undergo simultaneous pain then the process of tackling climate change would give them competitive advantage.
Much of the subsequent rage against the US was as much about that advantage as about concern for the planet.
At its summit in Brussels on Thursday and Friday, the EU decided instead to lead from the front at the June G8 summit, with a unilateral pledge to cut greenhouse gas emissions by 2020 by 20 per cent on their 1990 level - a further 10 per cent on the Kyoto target.
The offer is significant and welcome, particularly the carrot of a commitment to a full 30 per cent cut if others come on board. The EU produces 14 per cent of the world's greenhouse gas emissions, the US a quarter. A 20 per cent cut by the EU would therefore represent less than a 3 per cent global cut, but every bit helps. "It's a very courageous move on the part of the EU," said Ivy de Boer, head of the UN climate change secretariat in Bonn, which oversees the post-Kyoto efforts.
The European Council also agreed a mandatory requirement on members to take measures to raise to 20 per cent the share of energy needs met throughout the Union by renewable sources. Agreement was only possible, however, because of an understanding that the pain would be spread unevenly. The devil is in the detail, and we can be sure that when the commission brings out its specific country-by-country proposals for burden-sharing, both in relation to overall emission cuts and the renewable energy target, an almighty row will develop.
The new EU states argue that their heavy reliance on coal and the fact that they have already cut their emissions by 30 per cent means they should get a pass. And France, Slovakia, the Czech Republic and some of the Baltic states want their "clean" nuclear power to be regarded as in part meeting the requirement. Business groups say the target should not specify the technology, simply a carbon reduction figure, leaving the "efficiency" of the market to determine the means.
And then there's Ireland. Does a 20 per cent reduction mean a reduction on the 1990 figure, or on the 13 per cent above it which we were allowed in our Kyoto target? That target we have already overshot by some 12 percentage points, at enormous cost in terms of buying carbon credits on the international market. The difference is very substantial and will provide plenty of meat for diplomatic wrangling.
Ireland will almost certainly receive a renewable target above 20 per cent, which as the Government has already committed the country to achieving 33 per cent by 2020 should, in theory, not be problematic. Except that, the sceptics will say, the Government's track record on meeting Kyoto was so woeful, it can be asked quite reasonably why we should believe its commitment this time.