Long term climate implications of 2050 emission reduction targets

[1] A coupled atmosphere-ocean-carbon cycle model is used to examine the long term climate implications of various 2050 greenhouse gas emission reduction targets. All emission targets considered with less than 60% global reduction by 2050 break the 2.0 C threshold warming this century, a number that some have argued represents an upper bound on manageable climate warming. Even when emissions are stabilized at 90% below present levels at 2050, this 2.0 C threshold is eventually broken. Our results suggest that if a 2.0 C warming is to be avoided, direct CO2 capture from the air, together with subsequent sequestration, would eventually have to be introduced in addition to sustained 90% global carbon emissions reductions by 2050. Citation: Weaver, A. J., K. Zickfeld, A. Montenegro, and M. Eby (2007), Long term climate implications of 2050 emission reduction targets, Geophys. Res. Lett., 34, L19703, doi:10.1029/ 2007GL031018.