"I think we can get within spitting distance of the 17 percent," said Jake Schmidt, of the Natural Resources Defense Council.
In Doha, delegates are expected to extend the expiring Kyoto Protocol, an agreement limiting greenhouse emissions of some industrialized countries. The U.S. never ratified that agreement because it didn't include fast-growing developing countries including India and China, the world's top carbon emitter.
Delegates are also supposed to agree on a work plan for a wider pact that would include all countries. It's supposed to be adopted in 2015 and take effect five years later.
Figueres predicted that the conference would end with countries agreeing on a package of compromise decisions, "fully recognizing that whatever comes out of Doha is not at the level of ambition that we need."
Climate activists urged governments, especially from developed countries, to increase their commitments to fight climate change, which scientists say already is melting ice in the Arctic, raising sea levels and shifting weather patterns with impacts on floods and droughts.
"No developed country has come here and raised its emission-target as the science requires," said Mohamed Adow of Christian Aid.
Artur Runge-Metzger, the chief negotiator for the European Union, defended the EU's record on climate action, but admitted the pace of the talks was too slow.
"I'm often frustrated at the slow process," he said. "Still, I think it's worth investing (in these talks), because we invest for future generations."
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