Regarding the "Unmasking" what is already there point, this is addressed nicely by someone else. Does Lemmy let you forward/repost comments from other instances? Taken from @Azarova@hexbear.net
Aerosols from China’s industrialization were blocking sunlight. When they reduced aerosol emissions, the blocking effect diminished and caused apparent warming, but this warming was already ‘baked in’, if you will, because the GHG’s keeping the heat in were already present. Something similar on a more localized level happened a few years ago when some international(?) regulation passed that reduced the aerosol emissions of cargo ships. These emissions had kept a large band of North America cooler than it would be naturally and the introduction of the regulations caused a “termination shock” that resulted in warmer weather across the affected area. This is also the premise to a number of geo-engineering proposals, with the idea being that you could seed the upper atmosphere with aerosols that would hang up there for a considerable length of time but would spread across the planet, reducing the amount of sunlight that reaches the surface. This would certainly cool down the earth, but you also have the problem like with the shipping example, except on a planetary scale. As soon as you stop reapplying the aerosols, the planet will jump from its “engineered” temperature to its “actual” temperature extremely quickly.