I'm old enough to remember the 1970s global cooling scare, but hat's all it was - a scare.
Some climatologists of the time had a theory that interglacials such as the one we've been living in for the last 10K years had a mean lifetime of - well about 10K years. When they looked at climactic data, there was also a marked downturn in global temperatures during the middle 20th Century. So it was a reasonable theory to propose we were looking at the end of an interglacial with global temperatures likely to go into long term decline.
HOWEVER, that was only ever a minority point of view - albeit a well publicised one. The majority of global climate scientists had concluded that temperatures would either remain stable or, even begin to warm. They were looking at the various Milankovich Cycles that appear to have been driving the Pleistocene and Holocene climate changes.
We now know that the decline in the mid 20th Century is more linked to the huge aerosol emissions associated with the rapid industrialisation of the Northern Hemisphere, particularly in North America, the USSR and China, much of which was driven by high sulphur coal. As these economies gradually switched to cleaner coal and increasingly to oil and gas; and began to limit industrial emissions, the skies cleared and temperatures began to rise.
And if anyone is still reading - (hello) - the Medieval Warm Period is responsible for Greenland being MARGINALLY warmer than it is today - it was never green - that was Viking spin. Unlike the current warming, its effects were not global; the North Atlantic saw large amounts of warming, but the Pacific was cooler. It also came on much slower than the current warming, so its cause was probably not related to what we're seeing today.