If plants get most of their mass from CO2 in the air, why is the biomass of plants higher than the amount of CO2 in the atmosphere?

Question

I was reading today that there’s something like 8 gigatons of CO2 in the air, but more than 400 gigatons of biomass on earth (which is mostly plants). Can someone explain how this happens to me?

Edit: My numbers were off. There’s about 10x as much CO2 mass in the atmosphere as there is biomass on Earth

In: 43

Answer 1

Because they are two independent categories, there is no biomass represented in the co2 and no co2 in the biomass. There is exchange between the 2 categories but nothing is double counted.