a new concept they referred to as ‘planetary boundaries’.31 The Earth’s biosphere is an integrated system that can withstand significant pressures, but past a certain point it begins to break down. Drawing on data from Earth-systems science, they identified nine potentially destabilising processes that we have to keep under control if the system is to remain intact: climate change, biodiversity loss, ocean acidification, land-use change, nitrogen and phosphorous loading, freshwater use, atmospheric aerosol loading, chemical pollution and ozone depletion.
