![Earth as an open and a closed system](/images/posts/openClosedSystem.png)
This simple graphic depicts the concept that planet Earth is an open system with respect to energy flows, but a closed system with respect to mass transfers. One important aspect that this figure tries to depict is that material flow is fundamental for the sustainability of life on Earth. This material flow can only occurs because solar energy is used to drive biogeochemical cycling.
This graphic was comissioned by the Max Planck Institute for Biogeochemistry.