The atmosphere both inside and outside the UN climate conference has become more tense after talks were suspended for most of yesterday's session, and police detained up to 200 protesters on Copenhagen's streets.
With only days left before the conference closes on Friday, the wrangle over emission reductions froze a timetable for government ministers to negotiate a host of complex issues.
Though procedural in nature, the Africa-led suspension went to the core of suspicions by poor countries that wealthier ones were trying to soften their commitments and evade penalties for missing their targets.
Talks were halted most of the day, resuming only after conference president Connie Hedegaard of Denmark assured developing countries she was not trying to kill the Kyoto Protocol - the 1997 document that requires industrial nations to cut emissions and imposes penalties if they fail to do so. Kyoto makes no demands on developing countries.
Among the issues put on hold were whether China will be asked to make sacrifices similar to those demanded of the richer nations; whether it will open its carbon books to outside inspection; how to ensure every country counts its carbon emissions the same way; and how to raise a steady flow of money for poor countries to combat climate-linked economic disruptions such as rising seas, drought and floods.
Former US Vice President Al Gore told the conference that new data suggests a 75% chance the entire Arctic polar ice cap may disappear in the summertime as soon as five to seven years from now.
Mr Gore, who won a Nobel Peace prize for his work on climate change, joined the foreign ministers of Norway and Denmark in presenting two new reports on melting Arctic ice.
The world leaders are aiming for a political agreement in Copenhagen rather than a legally binding treaty.
Still, the goal is to nail down individual targets on emissions cuts and financing for developing countries in a deal that can be turned into a legally binding text next year.
Conference officials were struggling to cope with the increasing crush of people, which will only get worse when more than 100 world leaders arrive with large delegations and their own press corps.
More than 40,000 people applied to attend the conference, already straining to accommodate 15,000.
On the streets of the Danish capital police detained up to 200 people after protesters set fire to street barricades.
Protesters hurled fire bombs at helmeted riot officers who responded with tear gas, although there were no immediate reports of injuries.
Police briefly detained 1,200 people during demonstrations by climate activists over the weekend.
US special climate envoy Todd Stern said that with leaders due to arrive soon "any lost time is unhelpful". He added that in any complex negotiation "it never goes smoothly, never according to plan. There are always bumps".
Sakihito Ozawa, Japan's environment minister, said the African demand to spend more time on the industrial nations' targets "wasn't feasible".