UN considers putting mirrors in space
UN scientists are to consider moves such as putting mirrors in space and sprinkling iron in the sea in an attempt to cut global warming, the head of the IPCC said.
Speaking at the climate change conference in Cancun, Dr Rajendra Pachauri said the next report on global warming by the Intergovernmental Panel on Climate Change (IPCC) will not only look at the threat of rising temperatures but so-called "geo-engineering" options that could actually reverse warming.
The announcement implies that scientists are losing faith in a global deal to stop temperature rise by limiting emissions.
There are already low expectations for the latest round of UN talks being held in a luxury beach resort on the east coast of Mexico.
More than 190 countries are meeting at the heavily-guarded Moon Palace Hotel to try and find a way to limit emissions so that temperatures rise stays below 3.6F (2C).
The IPCC is responsible for setting out the scientific basis on which the talks are based.
Addressing the opening conference, Dr Pachauri said if mankind continues to pump out greenhouse gases at the current rate the world could experience catastrophic warming within the next fifty years.
He said the threat is so great that the fifth assessment report (AR5), due to be presented to the UN in 2014, will look at "geo-engineering options".
"The AR5 has been expanded and will in future focus on subjects like clouds and aerosols, geo-engineering and sustainability issues," he said.
Later this year IPCC "expert groups" will meet in Peru to discuss geo-engineering.
Options include putting mirrors in space to reflect sunlight or covering Greenland in a massive blanket so it does not melt.
Sprinkling iron filings in the ocean "fertilises" algae so that it sucks up CO2 and "seeding clouds" means that less sunlight can get in.
Other options include artificial "trees" that suck carbon dioxide out of the air, painting roofs white to reflect sunlight and man-made volcanoes that spray sulphate particles high in the atmosphere to scatter the sun's rays back into space.
Many have argued that the process could make climate change worse through unintended consequences.
Earlier this year the IPCC was forced to undergo a review after it was revealed that the last report to the UN, the AR4, included the mistaken claim that the Himalayan glaciers could melt by 2035. Critics called for the chairman to resign.
But Dr Pachauri insisted the review made the panel stronger than ever.
"We are confident that the IPCC will emerge stronger as a result of this exercise and live up to the expectations of the global community," he said.
The UN talks in Cancun are designed to find a way to limit global emissions in order to prevent global warming. However at the moment a treaty is unlikely as the world's two biggest emitters, China and the US, will not agree to legally binding targets.
Chris Huhne, the Climate Change Secretary, has already warned that a global deal is unlikely this time, although he insists the talks can make progress by agreeing on different aspects of the agreement such as forestry and climate finance.
Opening the talks, Felipe Calderón, the President of Mexico, insisted it was still possible for the world to reach a deal.
"Climate change is already a reality for us," he told delegates. "During the next two weeks, the whole world will be looking at you. It would be a tragedy not to overcome the hurdle of national interests."