Climate plans put forward in the run-up to the Cop26 summit are largely not “equal to the challenge we face”, says the World Wide Fund for Nature.
Countries are expected to submit climate targets before the conference, which is taking place in Britain in November.
Known as nationally determined contributions (NDC), they are expected to fall in line with the aim of limiting global warming to 1.5°C above pre-industrial levels.
Manuel Pulgar-Vidal, the WWF’s global lead on energy and climate, said there was a “yawning gap” between political promises and real action.
“Few of the NDCs submitted so far are equal to the challenge that we face, while many countries are still to submit revised NDCs at all,” he said.
“Cop26 must address this challenge and provide a strong political response that reflects the urgency for action.”
A WWF analysis of the climate plans found some positive signs, with more than 90 per cent of them incorporating nature-based solutions.
These include the restoration of forests and grasslands, which act to remove greenhouse gases from the atmosphere.
Protecting wetlands means that they can help to store flood water and reduce the risk of natural disasters brought about by climate change.
The G7 summit in Britain last month ended in an agreement to increase financing for nature-based efforts.
The UK says it will spend at least £3 billion ($4.1bn) on nature-based solutions over the next five years.
But some of the nature-based targets put forward before Cop26 are vague and not clearly linked to specific policies, the WWF said.
“Governments must come to Glasgow with rigorous, robust and credible plans to translate warm words on the international stage into real action at home,” Mr Pulgar-Vidal said.
Experts say that offsetting carbon output in the future is no substitute for immediate cuts to emissions.
Britain wants to reach net zero by 2050 and is urging businesses, regions and other emitters to adopt similar targets.
US President Joe Biden has a target of halving greenhouse gas emissions by 2030 compared with 2005 levels.
The Energy and Climate Intelligence Unit, a UK think tank, says that countries making up two thirds of global GDP have targets to be net zero by 2050.
More than 100 countries have yet to submit an updated NDC ahead of Cop26, according to the WWF.
The UK’s Prince Charles this week appealed to businesses to invest in nature to be able to benefit from it in future.
The Prince of Wales said he was “fed up with all the talking” on climate change as he urged finance leaders to drive ambitious action.
“This is not about making money on the one hand and being sustainable on the other,” he said.