Prof Edward Glaeser of Harvard has been studying environmentalism. His researches show the big chasm that often exists between local and global environmental concerns. Global warmists might believe we should move electricity production to renewable sources such as wind power; but environmentalists who value birdlife or open views might have doubts when turbines start chopping up birds and spoiling the view in their particular part of the world.

But, Glaeser finds, it is usually the local environmentalists who win out. A lot of local activists, for example, are trying to stop the spread of our cities. It's not just that they don't want new houses spoiling their view: it's the idea that our high-energy city lifestyles are wasteful and carbon-greedy, and mess up the planet.

Glaeser's actually looked into the energy that people use in US cities. And he's found that gasoline use is lower in large cities (in New York, everybody walks). Your January gas bill depends on how cold it is where you live, and your July air-conditioning bill on how hot the summers are – not the size of your town. And it is the places which regulate most that have the worst emissions record.

Places like London, with its draconian regulations to stop new building, might be a good example of the latter. Rather than try to push people out of cities into places and lifestyles where they will actually end up needing to dump more carbon on the planet, actually we should recognize that dense living is green. The local environmental groups might not like all the new building, but folk who look at the big picture should welcome it. (But of course, they don't.)