If I understand the information from this link correctly,
Instrumental temperature record
between 1950 to 1980 there were negative temperature anomalies in the years of those decades.
|decade||difference (°C)||difference (°F)|
This seems odd considering massive oil consumption started in 1880 IIRC, and by 1980 over 350 billions of oil barrels were already consumed (much more probably, since the data before 1950 isn't considered because there weren't reliable records).
Why was there a negative temperature anomaly between 1950 to 1980?