The world's richest nations must increase their greenhouse gas emission cuts to 25% by 2020, according to the first draft plan for a new climate treaty at the Copenhagen summit.
Representatives from 192 nations are participating at the conference with the aim of establishing a binding emissions reduction goal to curb global warming.
Developed countries have put forward a call for a 10-17% cut in emissions.
Participating countries have two potential temperature goals to curb global warming, three possible emissions targets for developed nations in 2020 and three global emission targets for 2050.
The draft requires developed nations to abide by legally binding greenhouse-gas reduction targets to lower global emissions by 25% to 45% by 2020 and 75% to 95% by 2050.
The countries are expected to ensure that the planet's temperature does not increase beyond either 1.5°C or 2°C to prevent dangerous climate change.
US, EU and China are supporting the 2°C target, while 43 small island and low-lying countries are opposing it.
The US has promised to lower emissions by 17% compared with 2005 levels by 2020, while Japan is ready to cut emissions by 25% in case a deal is finalised in Copenhagen.