‘One problem at a time’ just won’t do
Take a deep breath. Savour it for a moment. Now, consider this: None of our modern human ancestors ever breathed anything like it — and, the way things are going, nor will our descendants.
Since the Industrial Revolution began, human activity has substantially changed the atmosphere’s composition. Carbon-dioxide levels are higher today than they have been in at least 800,000 years. The amount of nitrogen and sulphur circulating through the Earth system has doubled. The ocean’s pH is changing at an unprecedented rate, reaching levels of acidity that marine organisms have not experienced in the last 20 million years.
Clearly, humans — who now occupy almost 40 per cent of the Earth’s ice-free land surface — are shaping many of the planet’s fundamental processes. According to Nobel laureate Paul Crutzen, this shift is so profound that it amounts to the beginning of a new epoch: The Anthropocene.
While some scientists believe that the Anthropocene actually began when humans started farming and domesticating animals, others (including me) consider it to be a more recent development. But, regardless of when the Anthropocene began, it is clear that humanity’s impact on the planet increased substantially after World War II’s end.
TIPPING POINT REACHED
Indeed, around 1950, the world seemed to have reached a tipping point, with practically every factor that heightened humanity’s impact on the planet — population, GDP, fertiliser use, the proliferation of telephones, and paper consumption, to name only a few — beginning to increase rapidly.
During this period, which the scientist Will Steffen dubbed the “Great Acceleration”, the human population became sufficiently large and connected, with high enough consumption, to become a major global force.
In a 2009 study, scientists concluded that, by crossing any of nine “planetary boundaries” — climate change, biodiversity loss, disruption of nitrogen and phosphorus cycles, land use, freshwater extraction, ocean acidification, ozone depletion, atmospheric aerosol loading, and chemical pollution — humans would increase the risk of fundamentally changing the Earth system.