For a while I’ve known that the 1970-2000 warming which caused the Global warming scare was a result of 1970s moves to reduce atmospheric pollution. This is clearly shown by the strong correlation between the areas with most intense warming and the areas with SO2 emissions (which I use a a proxy for industrial activity).
However, when I compare these with areas of acid rain (timescale unknown – I couldn’t find anything which clearly showed the areas subject to acid rain and gave a timescale)
It seems that the areas of acid rain are between the areas of emission, and highest rise in temperature (in other words greatest reduction in 1970s cooling causing pollution).
From this it is possible to conclude:
- That the process is not the direct formation of cloud by sulphates
- That the process takes longer to affect the weather than the simple formation of acid clouds
I have no doubt that the 1970-2000 warming was due to the reduction in pollution. However the exact nature of what was causing the cooling in the 1970s remains a mystery. It still seems likely to be cloud, and I wonder whether it could be stratospheric cloud, but to put it bluntly … it is very difficult researching something that went away in the 1970-2000 before much of the more modern monitoring and about 40 years before anyone even considered it a driver of global temperature.
I’ve wondered if it was fog. A lot of UK warming has been in the spring and autumn. You only have to walk into a fog bank to be aware of how much cooler it is inside.