At the COP26 conference this year, there's a lot of grumbling among activists that official venues are serving meat, even if it's locally-sourced meat. Animal agriculture has an outsized impact on global warming—up to 14.5% of annual global CO2 emissions, depending on which metrics you include. But here in Glasgow, a serving of meat also comes with a lesson in carbon footprint economics.

Attendees here at COP26 are now informed of the carbon impact of their meals as they peruse the menus.