Controversial technologies intended to offset the effects of atmospheric carbon should be banned until properly assessed, a group of politicians and scientists have warned, even as they urged developed nations to lead in cutting CO2 emissions.

A report by the Climate Overshoot Commission, chaired by former WTO boss Pascal Lamy and formed in 2022, said it was increasingly likely the world would exceed the target to keep temperature rises within 1.5 degrees Celsius above preindustrial levels.

It said richer countries needed to take the initiative to cut CO2 emissions and mobilize finance for poorer countries to adapt. Carbon removal technologies that minimize the risks of CO2 leaking back into the atmosphere should be promoted, the report said.

But potentially dangerous experimental geoengineering methods — including controversial "solar radiation modification" — need to be halted until they have been researched thoroughly, the report said.

"Countries should adopt a moratorium on the deployment of solar radiation modification and large-scale outdoor experiments that would carry risk of significant transboundary harm," it said.

Solar radiation modification refers to a range of proposed technologies designed to reflect sunlight away from the earth, including the direct injection of sulphates into the atmosphere. Last year, 60 scientists launched a global initiative aimed at banning all kinds of solar geoengineering.

"The world does not yet know enough to make informed decisions about solar radiation modification," the report said, adding that routine international reviews should take place to assess the potential risks.

"Early scientific evidence suggests that solar radiation modification could reduce some climate risks but would also introduce significant new risks," it said.

The report said slashing emissions should be a priority but will not be enough on its own and efforts need to be made to adapt to global warming, and deploy technologies to remove CO2 and "create space for the least industrialized countries to pursue their clean and sustainable energy transitions while fighting poverty and fulfilling their development imperatives."

The Climate Overshoot Commission also includes senior politicians from Canada, India, Pakistan, Spain and China.