In 2020, the International Maritime Organization introduced new regulations decreasing the sulfur content of shipping emissions (IMO2020). Since sulfur is a pollutant, it is expected that IMO2020 will improve air quality and health outcomes. These emissions, however, also lead to the formation of tiny particles in the air which brighten clouds, resulting in more sunlight reflected to space which helps cool the planet. Hence, by reducing sulfur emissions, IMO2020 will lead to planetary warming, yet the magnitude of this effect is hotly debated. In this work, we use a state-of-the-art Earth system model to assess the warming impact of IMO2020. We find that IMO2020 increases the global average temperature by around 0.05°C; the equivalent to 2–3 years of global warming.