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Comment by ricardobayes | Hacker News Reader

What's the reason it started to skyrocket after 1980 and not before? What made it stagnant or even slightly drop between 1940 and 1980?

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That mirrors global average temperature in general for that time period. Apparently it was because we were pumping sulfates into the atmosphere at an amazing rate from the 1940's until the EPA was born. Sulfates block sunlight and so mask the overall warming, at the cost of polluting the atmosphere.

See for example: https://www.sciencenews.org/article/50-years-ago-scientists-...

It has been proposed to intentionally resume injecting sulfates into the upper atmosphere in order to mitigate global warming[0]. (This is a horrible idea, but the jury's still out on whether it's better than the alternative.)

[0] https://en.wikipedia.org/wiki/Solar_geoengineering#Stratosph...

CO2-Emissions have been growing at an accelerating speed. Cumulative emissions double every 20-30 years. Half of CO2-emissions since 1750 have happened just since 1993.

https://ourworldindata.org/grapher/cumulative-co-emissions?c...

> What made it stagnant or even slightly drop between 1940 and 1980?

Well, there was that one really big war in the 1940s...

Doesn’t that suggest sea transportation may be a bigger contributor than greenhouse gasses? Industrial production was at its limits during that period, but I would imagine cross ocean cargo was down significantly.

It would be interesting to see what pandemic years looked like with thousands of ships sitting for months off shore.

Edit: there might be something to that idea - https://arctic.noaa.gov/Report-Card/Report-Card-2022/ArtMID/.... maybe globalism is the issue.

One more edit: container ships are effectively giant heat sinks with a ton (literally tons) of surface area (corrugated containers), sucking heat from the air and dumping it into the ocean. If that hypothesis has merit, I would expect the LA ports to have an increase in temperature during that same period.

Or there’s a complex interaction between Earth’s natural climate change and greenhouse gas emissions.

That’s definitely possible, but complexity makes errors more likely.

According to Google^TM, it takes 20-200 years for CO2 in the air to dissolve in the oceans and yet there are immediate effects during WW2 and COVID.

Aerosols from pollution could be a culprit?

We probably are getting better at measuring things and crunching the numbers as years pass by.

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