I apparently don’t understand your position.
The airborne fraction is " defined as the ratio of the annual increase in atmospheric CO2 to the CO2 emissions from human sources" Airborne fraction - Wikipedia
About half of human CO2 gets sequestered by sinks, the rest go in the air. That is why atmospheric CO2 levels are rising. I assume we all agree on that.
Since atmospheric CO2 levels are continuing to rise in what possible way are the CO2 sinks keeping up?