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So about 30% of today's warming of almost 1°C happened by the 1940s, and, after a little cooling until the 1970s, about 80% of overall warming has happened since then.
What caused the warming before the '40s? I've actually asked a scientist or two about this over the years, and the answer I've gotten is
- some increase in solar irradiance from about 1910-1940
- greenhouse gases, especially CO2
- reversing of ice-albedo feedback initially caused by volcanic aerosols, which together caused the Little Ice Age
By 1945 atmospheric CO2 was about 310 ppm, compared to 1850's 285 ppm, which gives a forcing of about 0.45 W/m2. (Compared to today's value of about 2 W/m2. Remember, logarithms change fastest in the beginning.) If climate sensitivity is 3°C, that'd be a warming of about 0.35°C. But I should probably use the transient climate response here, which is the temperature change at the time of CO2 doubling, i.e. without the long-term feedbacks. If it's 1.5°C, that's a warming of about 0.15-0.2°C.
I don't know about the ice-albedo feedback, but anyway it's a feedback not a forcing. But it would have caused some warming.
So it's likely that 90% or more of warming-to-date is from man. This is at a time when, now, the climate should be naturally cooling, due to a slight decline in solar irradiance since the 1950s, and some slight Milankovitch cooling. (I don't have a numerical handle on the latter, but the cycles change so slowly (fastest is 40,000 years) it's gotta be tiny.) This is why some scientists I see say man is responsible for 110% of warming since 1850.
Does this sound about right?