This is an absurd statement. Lets use bank accounts instead of CO2 to point out the absurdity.

Imagine every year a company makes $730,000 in revenue but spends $730,000 on various expenses. Its bank balance doesnt change because the income and expenses cancel out.

Now suppose the company starts receiving an additional $30,000 every year while its expenses stay the same. At the end of each year, its bank balance increases by $30,000.

By your logic, someone could argue: "That extra $30,000 can't be responsible for the growing bank balance because it's less than 5% of the company's total annual cash flow of $760,000."

That's obviously nonsense. The bank balance grows *entirely because of the net imbalance*, not because the extra income is a large fraction of the gross cash flowing through the account.

The carbon cycle works the same way. Natural emissions and natural uptake are both enormous and are approximately in balance. That 730 gigatons of CO2 released by natural sources has a corresponding 730 gigatons of CO2 capture from natural sinks. Its human emissions of CO2 that are the extra deposit that creates an ongoing imbalance, and that's why atmospheric CO2 continues to rise.

Also photosynthesis is not a source of CO2, on the contrary it's one of, if not the biggest carbon sink, reclaiming a significant portion of that 730 gigatons of CO2 released by volcanos and other sources.

> The bank balance grows entirely because of the net imbalance

Yes, this is my whole point. You wrote a long condescending comment accusing me of being a climate denier that fully agrees with me.

My point is that the actual amount of atmospheric increase per year is less than the amount humans put into the atmosphere per year, so 1) obviously humans are responsible for CC, and 2) could stop it at any time by dropping emissions below the amount the atmospheric increase amount.