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

Your numbers are somewhat off. There are about 3,000 gigatons of CO2 in the atmosphere. So there’s more CO2 in the atmosphere than there is biomass. Also there’s quite a lot of CO2 dissolved in the oceans – a bit less than 40,000 gigatons, so an order of magnitude more than in the air. It goes back and forth between oceans and atmosphere (currently it’s mainly going from the atmosphere to the oceans, increasing the water’s acidity).