Complex sentence: Scientists, industries, government bodies, and other organisations therefore need a tool to complement economic accounting and modelling with a systematic method to keep track of and display stocks and flows of the materials entering, staying within and leaving the different processes in the anthroposphere.
Split into simpler sentences: Scientists, industries, government bodies, and other organisations therefore need a tool that complements economic accounting and modelling. They need a systematic method to keep track of and display stocks and flows of the materials entering, staying within and leaving the different processes in the anthroposphere.