In 1992, the UN Framework Convention on Climate Change rightly called for a stabilisation of greenhouse gas concentrations at a level that would prevent dangerous climate change. The UN Climate talks that have just begun in Paris can and should underpin the decarbonisation of the global economy needed to meet that goal.
Signatories to the convention have agreed to limit global warming to no more than 2C, or 1.5C if the emerging science justifies it. To have a two-thirds probability of meeting the 2C target, total CO₂ emissions between 2011 and 2100 have to be less than 950bn tons. Emissions from energy need to fall from about 35bn tons this year to 10-15bn tons by 2050, and to zero by about 2070.
Such decarbonisation is achievable with current technologies. The cost will be modest assuming significant technological improvements that are within reach, through a combination of targeted research and learning by doing.