Regional Sensitivity of Surface Temperature to Nonuniform CO₂ Concentration on the Century Scale

Simulations from Earth System Model show that the rapid increase in atmospheric CO₂ concentration is one of the major reasons for climate change. Satellite data analysis shows that the atmospheric CO₂ concentration is globally nonuniform. There are evident regional discrepancies, mainly caused by anthropogenic carbon emissions. The impact of this spatial difference on global warming has not been thoroughly studied. We evaluated simulation results using the BNU-ESM (Earth System Model of Beijing Normal University) and compared the results with observational datasets. The results show that within a threshold of 2℃ temperature increase between 1901 and 2100, the CO₂ concentration increase forced by nonuniform CO₂ concentration was less than that by uniform CO₂ concentration, which was approximately 4.30 ppm. On the regional scale, the sensitivity of surface temperature to CO₂ concentration in China is lower than that in the United States, Europe, and the Northern Hemisphere. This might result from the combined impacts of CO₂-radiative forcing and climate feedback across these regions; however, this requires future investigation. The impact of nonuniform CO₂ concentration on surface temperature sensitivity could provide scientific support for estimating future carbon sinks under a carbon-neutral target.