Techniques put forward include growing crops to be burned in power stations, large-scale tree plantations, adding biochar to soil, adding nutrients to sea water to boost plankton and seaweed, and using chemicals to extract CO2 from the atmosphere -- to be buried deep underground.

But a comment piece published today in Nature shows that most, if not all, of these methods pose environmental risks -- and that much more research is needed before the wheels are set in motion on global-scale 'climate geoengineering' schemes.

The paper's author, Dr Phil Williamson, employed by the Natural Environment Research Council at UEA's School of Environmental Sciences, said: "In Paris, world leaders agreed to limit the increase in global average temperature above pre-industrial levels to well below 2oC -- and preferably below 1.5oC.

"But unless a lot more effort is made to cut carbon emissions, by the UK and other countries, we will have to work out how to safely remove very large amounts of CO2 from the atmosphere.