What We're In For What would our climate future look like if we stopped building any new infrastructure that used fossil fuels? Davis et al. (p. 1330 ; see the Perspective by Hoffert ) made the assumption that all existing infrastructure will be used until the end of its lifetime, after which it will be replaced by infrastructure that does not produce CO 2 . They then calculated the amount of additional CO 2 that will be added to the atmosphere. The outcome is that the concentration of atmospheric CO 2 would remain below 430 parts per million (ppm) (present levels are 390 ppm) and global mean temperatures would increase to 1.3°C above preindustrial values (about 0.5°C above present), well below current targets of 450 ppm and 2°C, respectively.

Future CO 2 Emissions and Climate Change from Existing Energy Infrastructure