Typing characters is maybe 1% of the job. The other 99% is understanding how the change affects everything else. Changing a single line of code in a function called by 1000 other functions each themselves called in 10 other functions can still potentially be more work and a bigger change than changing 9000 lines of code in a function called once.
The carbon sequestered in the earth in the form of coal, oil and gas hasn’t always been in the earth. After all, hydro carbons are in fact hundreds of millions of years of dead trees buried under mud sequestering atmospheric CO2. Which implies there was a time with all that CO2 in the air yet still trees to capture it. By releasing it all, we reset the biosphere’s clock to about a time when earth supported a different kind of life (one without us in it), but life nonetheless.
Frankly, the comparisons to Mars and Venus seem a bit overblown.