Wish I'd said that

The [UK] government has now promised to cut greenhouse gases by 50% by 2027, which means that, with a following wind, the UK could meet its legally-binding target of 80% by 2050. For this we should be grateful. But the coalition has resolved the tension between green and growth in a less than convincing fashion: by dumping responsibility for the environmental impacts on someone else. The carbon cut we have made so far, and the carbon cut we are likely to make by 2027, have been achieved by means of a simple device: allowing other countries, principally China, to run polluting industries on our behalf. George Monbiot, 'the Guardian', 23rd May

I have been saying this for years. In climate change, as in other social and environmental challenges, narrow targets are useless. They are far too easily evaded or gamed, so that any supposed social problem is shifted away from the scope of explicit targeting. We should be targeting not British greenhouse gas emissions, nor even global greenhouse gas emissions, but climate instability. If we did that by issuing Climate Stability Bonds, we'd be addressing this global, urgent concern with maximum efficiency. Other targets, as is the UK Government's, are likely to be inefficient and ineffective.