The Zero Emissions Commitment Model Intercomparison Project (ZECMIP) used 18 different ESMs to simulate what would happen in a world where global emissions suddenly ceased after the world had emitted a total 3667 Gigatons of CO2 (or 1000 Gigatons of carbon) – which would be expected to result in warming of around 2C compared to preindustrial levels. It also examined a case where emissions gradually decreased to net zero and found similar results to an abrupt cutoff after net-zero is reached.