I've put off doing a "the latest from Copenhagen" post as events keep shifting and along with them the outlook for a real agreement. As of the point that I'm typing this the outlook just swung from dismal to hopeful (a qualified hopeful, of course - see the bit about "3C"), but that could change by the time you're done reading it.

China signalled concessions on monitoring of emission curbs, and the US said it would commit money for developing countries.Leaders are likely to have big choices to make when they meet on Friday.

However, a leaked document from the UN climate convention indicates the best deal likely here will not keep the temperature rise below 2C (3.6F). Even if countries implement their biggest pledges, a rise of 3C (5.4F) is indicated, it concluded.

One constant I can point you to, though, is the on-site reporting by former Sustainability Director (and former philly.com Green columnist) Mark Alan Hughes, who now does a column called Built for the Daily News. Hughes is video-blogging from Copenhagen for PlanPhilly and brings his bracing frankness toassessing what's going on and what it means. Plus he assures me he's been eating vegan sandwiches, so if the whole deal breaks down completely, at least we'll have that.