Facts4Paris: The later we start reducing, the steeper the decline to 2050.
Our middle-of-the-range sum of INDCs gives an approximate figure of 55 Gt of emissions by 2030 (GWP AR4 metric). This is above 2020 emission projections for both the Copenhagen and Cancun pledges. It suggests that we are heading in the wrong direction. Global emissions need to come down, not increase further, if the world is to have a likely change of keeping warming within 2°C.
Looking at all IPCC AR5 scenarios for 2°C starting in either 2010, 2020 or 2030 there is a clear penalty for delayed mitigation action. As was found by IPCC, 2050 emissions levels for 2°C compatible scenarios are 40% to 70% below 2010 by 2050. Almost all scenarios pass through that range, regardless of whether the decline starts softly in 2010 or goes into free-fall from 2031. Combining the INDC quantifications with the 2°C scenarios leaves just one conclusion: to achieve 2°C INDCs need to be enhanced...Otherwise we need a miracle emissions-reduction solution from 2031.