While G20 delegates argued about how to solve the European sovereign debt crisis in Los Cabos, Mexico, delegates from across the world poured into Rio de Janeiro to attend the UN’s sustainable development summit to discuss how to tackle climate change.

But, despite the heavyweight guest list and agenda, the overall feeling was one of inertia. Ban Ki-moon, the UN secretary-general, said that progress on climate change was too slow and urged world leaders to do more.