[E. Pluribus Unum]

The atmosphere contains 0.04% CO2.

Man is responsible for 3.4% of that 0.04%

The total amount of anthropogenic CO2 In the atmosphere is therefore 0.0014%

Completely eliminate man’s contribution and the Earth’s atmosphere still contains 0.04% CO2.

[palmer]

The rise from 0.018% to 0.042% is almost entirely manmade. If we just had a natural rise from post-Little Ice Age warming, there would have been a rise from 0.018% to 0.019% at most. That's based on the long term record showing about 100 ppm rise for 10C of warming or 100 ppm fall for 10C of cooling

See the charts here: https://joannenova.com.au/global-warming-2/ice-core-graph/. She shows that CO2 lags temperature. That means the main driver of CO2 is from rising or falling temperatures. The CO2 to temperature link is very weak and if it were not weak we would have had runaway greenhouse a billion years ago.

The point is that warming following the Little Ice Age was about 1C. That would cause about 10 ppm rise in CO2. Instead we had 140 ppm rise in CO2. More importantly there's 2.5 ppm rise in CO2 every year, year over year (above the annual cycle). That amount cannot be caused by warming oceans in the past century or centuries. The only logical explanation is manmade CO2.

Man is responsible for 3.4% of that 0.04%

Manmade CO2 is about 3% of naturally created CO2. Man's uptake of CO2 is essentially zero. Nature's uptake is roughly equal to naturally created CO2. When you use the 3.4% figure you are not including natural uptake. IOW you are comparing the year over year rise in your chart to the entire annual rise and ignoring the annual drop.