Dynamic equilibrium and the water and carbon cycles

• Most natural systems, unaffected by human activity, exist in a state of dynamic equilibrium. They are dynamic in the sense that they have continuous inputs, throughputs, outputs and variable stores of energy materials
• In the long term, however, flows and stores usually maintain a balance, allowing a system to retain its stability. Negative feedback oops within systems restore balance
• In a drainage basin unusually heavy rainfall will increase the amount of water stored in aquifers. This in turn will raise the water table, increasing flow from springs until the water table reverts to normal levels
• In the carbon cycle, burning fossil fuels increases atmospheric CO2 but at the same time stimulates photosynthesis. This negative feedback response should remove excess CO2 from the atmosphere and restore equilibrium