evidence: One common cause of confusion is the mixing up of two very different scenarios: a world where CO2 concentrations remain at today’s levels; and a world where all emissions are immediately cut to zero (or net-zero, which would have the same effect; what ultimately matters is the balance of CO2 sources and sinks, though the extent to which sinks are natural or anthropogenic can be a tricky question). [...] If emissions are cut to zero, on the other hand, atmospheric concentrations of CO2 would quickly fall, before eventually stabilising at a lower level. [...] At the same time, the land and ocean are absorbing about half of the CO2 that humans emit each year. If emissions go to zero, these "carbon sinks" continue to take up some of the extra CO2 that was emitted in the past – quickly at first and then more slowly over time as they move toward a new equilibrium. This reduces the levels of CO2 in the atmosphere and, thus, the warming it causes.