the atmosphere has 0.04% greenhouse gases in it- Carbon from man amounts to just 3.4% or so of that 0.04%-
therefore 3.4% of 0.04 = 0.00136
only roughly 3% is from man
EPA document supports ~3% of atmospheric carbon dioxide is attributable to human sources
I’ve given it another .4% because I’ve seen more recent figures show that amount, some a little more, some a little less- but it’s roughly 3.4%
at any rate- the amount is still far far far too small to have global impact-
Humans contribute approximately 3.4 percent of annual CO2 emissions. However, small increases in annual CO2 emissions, whether from humans or any other source, can lead to a large CO2 accumulation over time because CO2 molecules can remain in the atmosphere for more than a century.
A lot of the presentation is just plain incorrect like the next slide where they use the 3.4% to derive a human contribution to the greenhouse effect. In any case the 3.4% is the ratio of human emission to natural emissions. IOW natural emissions are 30 times greater than human.
The missing fact is that natural emissions are more or less balanced by natural uptake. IOW natural uptake is also 30 times human emissions. That's why they add the phrase "small increases ... can lead to a large accumulation over time" That's their round about way of acknowledging that the rise from 280 ppm to 400 ppm (and the 2.5ppm rise every year) is now essentially manmade.
The WUWT link you provided has the same conclusion: "The chart refers to the annual increase in CO2, not the total amount. So it is misleading." Like FR, the threads at WUWT are left up so we can see the arguments from both side, even if the article or headline is "wrong". In any case, the now defunct NCPA, Dr. Tim Ball, and Heritage.org are all the same, and they are the only sources of "3.4%" It's never going to gain any nontrivial scientific following. However there are scientists posting similar arguments on that thread you linked. In particular richardscourtney, a bonafide peer-reviewed scientist. But notice one important detail, he does not promote a number like "3.4%" or any other number. But his scientific view is that some of the rise of CO2 could be natural.