Government ministers start arriving in Warsaw Tuesday for the final stretch of UN climate talks seeking to pave the way to a global deal in 2015 on curbing global warming.
With only four days left in the annual round of notoriously fractious negotiations, delegates and observers say little progress has been made on key agenda points—with finance for poor countries proving the most divisive issue.
"The finance issue is creating a lot of anger here," Alden Meyer, strategy director of US environmental group, the Union of Concerned Scientists, told AFP.
"Hopefully the ministers can come in now and start working on some on the political elements... and finally come up with compromises and defuse some of the tensions."
Developing countries want rich nations to show how they intend keeping a promise made in 2009 to ramp up finance to $100 billion a year by 2020.
The money is meant to help them prepare for and cope with the fallout from climate change.
But developed nations dealing with the effects of the global economic crisis, are hesitant to put any figures on the table for the 2020 target, for shorter-term funding, or commit to a "loss and damage" mechanism they fear will make them liable for climate damage compensation.
"Developing countries need to feel confident that the commitment to that 100 billion is still on the table despite current financial circumstances," UN climate chief Christiana Figueres told journalists on Monday.
"There needs to be more clarity on how that funding is going to be mobilised.
Ministers will meet for talks on finance on Wednesday.
The roadmap to a new, global climate deal due to be signed by the 2015 UN conference in Paris, is also proving a tough nut for negotiators to crack.
The deal must bind all the world's nations to climate-altering greenhouse gas emissions cuts in a bid to meet the UN target of limiting average global warming to 2.0 degrees Celsius (3.6 deg Fahrenheit) over pre-Industrial Revolution levels.
But they do not agree on the deadline for final country emissions pledges—with some nations saying this could happen only after Paris.
US negotiator Todd Stern said Monday there was "considerable convergence" around the idea that countries should be allowed to make their own emissions curb "commitments", which would be opened to scrutiny and which the country could then revise.
Some, however, want more than mere peer pressure on countries to make sure their pledges are adequate to halt the march of global warming.
Deep disagreement also remains on whether rich nations with a long history of emissions should bear a bigger emissions-cutting burden.
Explore further: Ocean acidification changes balance of biofouling communities