US President Barack Obama hailed the deal as "unprecedented" but also warned that much remains to be done. A spokesperson for the European Commission voiced satisfaction that agreement had been reached but stressed that it fell short of expectations.

No specific targets for cuts in greenhouse gasses have been set. It is just one of the unresolved issues that have been left for talks next year. The agreement only specifies that global warming should not rise more than two degrees Celsius above pre-industrial era levels.

It also proposes to create a fund to help poor countries tackle the effects of global warming. The fund will be financed by rich countries, which by 2020 should contribute 100 billion dollars every year. Monitoring of the agreement will remain a national matter, a concession to China, one of the world's biggest emitters of greenhouse gasses.

Negotiations at the two-week summit often proved difficult, even after the arrival of world leaders. President Obama had several bilateral meetings with Chinese Prime Minister Wen Jiabao to discuss the monitoring of the agreement. And poor countries accused rich nations of insufficient will to tackle climate change on a global scale.