“Within the Paris agreement there’s an implicit assumption that there will need to be greenhouse gases removed,” said Phil Williamson, a scientist at the U.K.’s University of East Anglia, who worked on the report. “Climate geoengineering is what countries have agreed to do, although they haven’t really realized that they’ve agreed to do it.” 
“Our backs are against the wall and we must now start the process of preparing for geo-engineering,” the letter said. “We must do this in the knowledge that its chances of success are small and the risks of implementation are great.”
The Paris Agreement commits countries to a system of volutary national climate action plans, which will be reviewed every five years in a bid to keep average global temperature increases well below 2C and ideally below 1.5C. However, according to official estimates current national plans will result in temperature increases of almost 3C this century and the letter dismisses the idea far more ambitious plans and targets will be agreed in five years as “naïve”. 
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