Climate negotiators face a "daunting task" to deliver a new set of targets
Progress towards developing a global strategy to cut emissions is too slow, according to environmental group WWF.
It issued its warning at the end of key UN talks that considered what measures should replace the current set of climate targets, which expire in 2012.
The group said the negotiations in Bonn had failed to make any progress because nations were presenting "shopping lists, not blueprints" for action.
The UN's climate chief agreed that the process needed to become more focused.
The two-week gathering is part of a process that will culminate at a key conference in Copenhagen towards the end of 2009.
It is hoped that the summit in the Danish capital will see nations agree on a new set of targets to reduce greenhouse gas emissions.
"Progress at the end of this second round in a series of UN climate negotiations was considered feeble," said Kathrin Gutmann, WWF's climate policy co-ordinator.
"The science tells us that governments need to think at a much larger scale of action than ever before to get climate change under control," she added.
Yvo de Boer, executive secretary of the UN Framework Convention on Climate Change, agreed that the talks needed to become more focused.
But he added that the talks had seen delegates shift from discussions to negotiations.
"We now have a clearer understanding among governments on what countries would ultimately like to see written into a long-term agreement to address climate change," he observed.
"But with a little more than a year to go to Copenhagen, the challenge to come to that agreement remains daunting."
As well as setting new targets for reducing emissions, the talks also have to deliver agreements on how to help developing nations adapt to shifts in the climate, the development of green technology, and how the international community is going to finance the measures.
The next set of talks will be held in Ghana in August, with the final round of negotiations in 2008 being held in Poland in December.