Part I: Description and performance for present day conditions. (ipcc.ch)
The year 2000 ozone concentration still produces a 39 % higher iRF when imposed in the 1850 climate state than in the climate state produced by the Historical, all - forcings simulation (and 77 % higher than when constant present day conditions are imposed). (climateaudit.org)
This study focuses only on biogeophysical effects of forest disturbance, so atmospheric CO2 concentrations are held fixed to present day conditions of 367 ppm. (journals.plos.org)