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)
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.