U.N. talks on a new global warming pact went into overtime Saturday as negotiators considered a draft agreement that environmentalists complain fails to clearly define the responsibilities countries are due to accept at a key summit in Paris next year.
The two-week meeting of representatives from more than 190 nations was scheduled to close Friday, but the yearly climate gatherings have rarely ended on time.
One of the most problematic issues left unresolved was deciding what information should go into the pledges due for a planned Paris agreement.
Rich countries insisted the pledges focus on efforts to control emissions of carbon dioxide and other heat-trapping greenhouse gases and were resisting demands that they include promises of financing to help poor countries absorb the effects of climate change, which the U.N. environment agency last week estimated will amount to at least $200 billion annually by 2050.
Environmentalists complained that the draft that delegates were considering Saturday puts off decisions on financing.
"The current text is in my view the worst possible text," said Jan Kowalzig of Oxfam.
Bolivia's chief negotiator, Rene Orellana, on Friday accused rich countries, including the United States, of "an attitude of shirking the responsibility of the provision of finance" and technology transfer to poor nations.
Meanwhile, top carbon polluter China and other major developing countries opposed plans for a review process that would allow the pledges to be compared against one another before Paris.
Their reluctance angered some delegates from countries on the front lines of climate change.
"We are shocked that some of our colleagues would want to avoid a process to hold their proposed targets up to the light," said Tony de Brum, the foreign minister of the Marshall Islands, a Pacific nation of low-lying atolls at risk of being flooded by rising seas.
Expectations had been relatively low for the Lima talks.
"This agreement papers over the toughest decisions, which are still to be made in the 12 months ahead of Paris," said Paul Bledsoe, climate specialist at the German Marshall Fund think tank.
Though negotiating tactics always play a role, virtually all disputes in the U.N. talks reflect the wider issue of how to divide the burden of fixing the planetary warming that scientists say results from human activity, primarily the burning of oil, coal and natural gas.
Historically, Western nations are the biggest emitters. Currently, most CO2 emissions are coming from developing countries as they grow their economies and lift millions of people out of poverty.
During a brief stop in Lima on Thursday, U.S. Secretary of State John Kerry said fixing the problem was "everyone's responsibility, because it's the net amount of carbon that matters, not each country's share."
According to the U.N.'s scientific panel on climate change, the world can pump out no more than about 1 trillion tons of carbon to have a likely chance of avoiding dangerous levels of warming. It already has spent more than half of that carbon budget as emissions continue to rise, driven by growth in China and other emerging economies.
Scientific reports say climate impacts are already happening and include rising sea levels, intensifying heat waves and shifts in weather patterns causing floods in some areas and droughts in others.
The U.N. weather agency said last week that 2014 could become the hottest year on record.