When comparing the global emissions reductions in 2050 from various studies, we find that different studies use different targets such as 50% below 2005 levels (about 38% below 1990 levels) in Refs. [27,40]; 57% below 2005 levels (about 46% below 1990 levels) in Ref. [1]; 66% below 2005 levels (about 57% below 1990 levels) in Ref. [46]. In summary, Ref. [37] evaluating 193 published emissions scenarios from different models concludes that to maintain at least a likely chance (>66%) of reaching the 2 C target in 2100, total anthropogenic CO2 emissions should be limited in a range of 415e460 ppm in 2100 or 35e55% below 1990 levels in 2050.