planetary boundary

Fifteen years ago a group of scientists identified nine processes vital to the Earth system in an attempt to clarify what climate change was going to mean to us all.  Three of these processes are based on what we are removing from the environment — fresh water, land available for use, species (reducing biodiversity).  The other nine are what we have put into the system to its detriment — greenhouse gases, ozone-depleting chemicals, things which have not existed in the environment before (such as plastics, concrete, synthetic chemicals and genetically modified organisms), aerosols, and nutrient overloads usually from fertilisers.

The planet can cope with a certain amount of all this but there is a boundary beyond which we enter the danger zone where we are all at risk.  As we approach each boundary it is possible for us to reduce the damage and return to safety.  For example, in the case of ozone-depleting chemicals we have managed to change our behaviour, to reduce these gases and stop the ozone hole from getting bigger.  But in the case of the loss of available fresh water we are seriously in the red. We need to focus on the planetary boundaries that we have crossed and find our way back again.