This has been a known effect of reducing aerosols for a while, no surprise that the country producing the most of them and doing the most to reduce them has the most impact on this particular effect. It’s also (one of the reasons) why geoengineering by releasing tons of aerosols into the environment is a bad idea - once we start we would be stuck doing it forever regardless of its knock on effects because the snap back if stopped would be really bad.

It is important to note that China’s action hasn’t caused additional warming, Samset stresses. Rather, it has “unmasked” what was already there. “The warming was always there, we just had some artificial cooling from pollution, and in removing the pollution we are now seeing the full effect of the greenhouse-gas driven warming,”

Important enough the info had to be hidden three quarters of the way though the article.