Within climate change what you're asking about is called TCRE or "transient climate response to cumulative carbon emissions". E.g. this research article should answer some of your questions. It's an analysis of historical temperature, CO^2 emissions, and the relation between the two: https://royalsocietypublishing.org/doi/full/10.1098/rsta.201...

1. https://en.wikipedia.org/wiki/Transient_climate_response_to_...

Also note that US population was about 1/3 and 2/3 of present in 1940 and 1980 respectively. The developing world has grown a lot faster than that. So the number of people living the highest-carbon lifestyles is up while the number of people aspiring to do so is WAY up.

Not all reactions are linear. Some have discreet "breaking points", after which become visible.

Also, if we compare 1980 to today, or even 2010, it's like the stone age re: production and consumption.

Population was just 4.4B -- now it's 7.7, almost double.

Large swaths were in far more dire poverty and much less consumption. Chinese industrial production was not a thing -- now it's the biggest industrial site in the world. The whole of USSR and Eastern Europe were communist (and would be for 10 years still).

And even Americans consumed much much less than today. Consider how little gadgets and stuff the average person had in 1980. Even clothes were much more valued than today's "quick fashion". Malls where just starting to be built everywhere (now the world's a big mall, and the internet can deliver to your door in the next day, so they aren't even needed).

US production here shows more than double too: https://www.macrotrends.net/2583/industrial-production-histo...