A report recently prepared by Ecofys and Climate Analytics on commission by the Children’s Investment Fund Foundation, entitled ‘Closing the 2020 emissions gap: Issues, options and strategies’, considers how greenhouse-gas emissions can be cut to limit global warming. The emissions gap refers to the discrepancy between 2020 levels of emissions which would be consistent with the goal to hold warming below 2°C or to 1.5°C , and the levels of emissions expected for 2020 based on current emission-reduction pledges by all individual countries – which are set to be much higher in total.
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.