Short-lived climate forcers have long-term climate impacts via the carbon-climate feedback

Short-lived climate forcers (SLCFs) like methane, ozone and aerosols have a shorter atmospheric lifetime than CO2 and are often assumed to have a short-term effect on the climate system: should their emissions cease, so would their radiative forcing (RF). However, via their climate impact, SLCFs can affect carbon sinks and atmospheric CO2 causing additional climate change. Here, we use a compact Earth system model to attribute CO2 RF to direct CO2 emissions and to climate-carbon feedbacks since the pre-industrial era. We estimate the climate-carbon feedback contributed 93 +/- 50 mW m(-2) (similar to 5%) to total RF of CO2 in 2010. Of this, SLCF impacts were -13 +/- 50 mW m(-2), made up of cooling (-115 +/- 43 mW m(-2)) and warming (102 +/- 26 mW m(-2)) terms that largely cancel. This study illustrates the long-term impact that short-lived species have on climate and indicates that past (and future) change in atmospheric CO2 cannot be attributed only to CO2 emissions.