Residual emissions: Remaining gross emissions when net-zero, and subsequently, netnegative, emissions are reached. Can apply to both net zero CO2 and net zero GHG emissions, from local to global scales and at company or sector level. To reach net-zero emissions, the amount of CDR must equal the amount of residual emissions over a given period. To reach net-negative emissions, the amount of CDR must exceed residual emissions.
Source : The State of CDR, 2nd Edition