One is to restrict the carbon-dioxide emissions of the 11, 000 companies trading on it to an agreed cap.

ECONOMIST: A market in need of a miracle

But the UN's Environment Programme reckons that even if all countries honour their existing commitments, global emissions in 2020 would exceed the likeliest total consistent with that pledge by the equivalent of up to 11 gigatonnes of carbon dioxide.

ECONOMIST: Climate-change talks

Figures for 2010 show the island emitted 379.1kt of carbon dioxide equivalent, which was a decrease of 11.6% on the 2009 figures.

BBC: Guernsey greenhouse gas decrease continues