Negotiators pored over revised drafts Friday, hours before the U.N. talks in Madrid were officially meant to end.
Germany's environment minister said a decision Thursday by European Union leaders in Brussels to make the bloc " climate neutral" by 2050 would provide a boost to negotiations in the Spanish capital during the final hours.
"With this, we can convince other major economies to join in and show how they want to reduce carbon emissions," German minister Svenja Schulze told The Associated Press
EU countries and others have made clear that they would prefer not to reach a deal on international carbon markets than to approve one that could undermine efforts to cut greenhouse gas emissions.
Environmental groups planned to stage protests outside the climate summit venue in Madrid later Friday.
Scientists say big cuts to global emissions have to start next year if the 2015 Paris agreement's goal of keeping global warming at 2 degrees Celsius (3.6 Fahrenheit) but ideally 1.5 degrees Celsius (2.7 F) by the end of the century is to be achieved.