"This is a turning point in negotiations on climate change," said the Gulf state's deputy prime minister, Abdullah bin Hamad Al-Attiyah, at the opening session.
"Before us in the coming days is a golden opportunity. We must seize it," he said.
Delegates from 194 members are meant to commit to concrete cuts in emissions of heat-trapping gases. They will work in Doha to hammer out details of that treaty, to be signed by 2015 and enter into force by 2020.
The European Union and about 10 other countries plan to commit themselves to also extend reduction targets agreed under the Kyoto Protocol, which expires this year.//DPA