While the diplomats in Cancun (2010) agreed to limit global warming to 2 degrees Celcius, the scientists were concluding that the warming cannot safely exceed 1.5 degrees. Aiming at the 2 degree target, the Fifth Assessment Report of the International Panel on Climate Change's Working Group 3 (on adaptation and mitigation, 2014) examined over 400 scenarios of economic development to the year 2100 (integrated assessment models) giving optimistic prognoses notably featuring continued global economic growth. Yet virtually all of these scenarios relied on the massive deployment of unproven carbon storage and capture technologies.
Following the 2015 COP21 agreement, the official target was reduced to the safer 1.5 degree level but the total remaining carbon budget for this goal is only 10 years at current emission levels and it would seem all but impossible to achieve.
But can we still limit the warming to 2 degrees? To attain this more modest goal, levels of investment in new technologies and annual rates of decarbonization must be far higher than anything we have experienced in the past. Can it be done without staking our future on carbon storage and capture?