Initial reaction to the negotiating text submitted Friday underscored the split between the U.S.-led wealthy countries and countries still struggling to overcome poverty and catch up with the modern world.
The tightly focused document was meant to lay out the crunch themes for environment ministers to wrestle with as they prepare for a summit of some 110 heads of state and government at the end of next week.
U.S. delegate Jonathan Pershing said the draft failed to address the contentious issue of carbon emissions by emerging economies.
"The current draft didn't work in terms of where it is headed," Pershing said in the plenary, supported by the European Union, Japan and Norway.
Environment ministers started arriving in the Danish capital Saturday for informal talks before world leaders join the summit late next week.
On the chilly streets outside the conference center, police assigned extra squads to watch thousands of protesters gathering for a march to demand that leaders act now to fight climate change.
"All week we have heard a string of excuses from northern countries to make adequate reparations for the ecological crisis that they have caused," said Lidy Nacpil, of the Jubilee South Coalition. "We are taking to the streets to demand that the ecological debt is repaid to the people of the South," she said in a statement.
Environmental activists also rallied in Asia to increase the pressure on climate negotiators in Copenhagen.
"There's not much time left for us to save our climate," said Liu Shuang, an officer with Greenpeace China, as traditional drummers kept up a steady beat in front of an ancient Beijing gate with about 200 people looking on.
Thousands marched in a "Walk Against Warming" in major cities acrosss Australia and about 200 Filipino activists staged a festive rally in Manila to mark the Global Day of Action on climate change. Dozens of Indonesian environmental activists rallied in front of the US Embassy in Jakarta.
The draft distributed to the 192-nation conference set no firm figures on financing or on cutting greenhouse gas emissions.
It said all countries together should reduce emissions by a range of 50 percent to 95 percent by 2050, and rich countries should cut emissions by 25 to 40 percent by 2020, in both cases using 1990 as the baseline year.
The draft continues the system for industrial countries set up in the 1997 Kyoto Protocol by which they are legally bound to targets for emission reductions and face penalties if they fall short. It makes no similar requirements of developing countries like China and India, which have pledged to reduce the growth rate of emissions but reject the notion of turning those voluntary pledges into legal commitments.