The report shows how, despite present political obstacles, it is still possible to meet the goal of 2°C or lower. However, if no further action beyond that which has been pledged within the context of the Kyoto Protocol is taken, the increase in global mean temperature will be as great as 3-3.6 degrees by 2100. Particular attention is given in the report to the extent to which warming could be limited by reductions in non-CO2 emissions, such as methane, HFCs and air pollutants including black carbon, which has thus far been a matter of some ambiguity.
The paper concludes that reductions in these non-CO2 gases are a necessary but not sufficient condition to limit warming, and that without deep CO2 reductions the 2020 gap will not be closed. What is more, focusing on reducing non-CO2 emissions is not a viable strategy to “buy time” if action to reduce CO2 emissions stalls.
A ten-year delay, for example, in starting to cut CO2 emissions alone would increase from 20% to 50% the probability of the planet warming by more than 2°C in the 21st century. Hence a comprehensive climate change mitigation strategy requires that measures to reduce both CO2 and non-CO2 emissions are put in place alongside one another.
The paper gives an overview of some of the initiatives, called Wedging the Gap, that could be implemented in a green growth approach to close the emissions gap.