Negotiators have been accused by charities and NGOs of not moving fast enough at interim talks in Germany.
Countries are working towards options to limit greenhouse gas emissions from 2020 ahead of a crunch December summit.
But the UN said progress had been made in streamlining the text of a new agreement.
The climate talks in Bonn are designed to pave the way towards the signing of a new deal in Paris at the end of the year that will shape the world's actions over climate change for decades to come.
On Wednesday, Christian Aid said there was a danger of ''sleepwalking into Paris''.
''There has been too much time spent fiddling around with the unimportant details of the text,'' said the charity's senior climate change adviser, Mohamed Adow.
''Negotiators have acted like schoolchildren colouring in their homework timetable and not getting round to any actual homework.''
He said negotiations must deliver ''a robust text soon otherwise they will cause further unacceptable delays and result in countries sleepwalking into Paris''.
Momentum is building towards the UN climate summit in Paris.
Key sticking points include finance to help developing countries adapt to climate change and agreeing on immediate and binding targets for carbon emissions.
But negotiating time is running out with only around 10 days' worth of negotiations remaining after the Bonn talks close.
On Wednesday, countries discussed new draft text for the agreement designed to boost climate action in the short term.
A network of NGOs known as the Climate Action Network said there were ''solid suggestions for delivering near-term action that will be up for decision in Paris''.
''Parties have moved forwards to consolidate the draft Paris text here in Bonn, this will help give ministers more clarity and enable them to provide political steer on crunch issues over the coming months,'' said Jake Schmidt of the Natural Resources Defense Council.
Delegates will return to Bonn in August and October for another two rounds of climate talks, before the summit in Paris at the end of the year.
Scientists say ambitious action is needed to avert the most severe impacts of climate change.
So far, more than 30 countries have pledged to limit emissions of greenhouse gases, with around 150 smaller countries yet to set goals.
Analysis suggests these do not go far enough to keep global warming below 2C.
International talks towards a new global climate deal are due to end on Thursday, amid concern that progress has been slow.