SOURCE: The Guardian
DATE: December 20, 2018
SNIP: Policymakers have severely underestimated the risks of ecological tipping points, according to a study that shows 45% of all potential environmental collapses are interrelated and could amplify one another.
The authors said their paper, published in the journal Science, highlights how overstressed and overlapping natural systems are combining to throw up a growing number of unwelcome surprises.
“The risks are greater than assumed because the interactions are more dynamic,” said Juan Rocha of the Stockholm Resilience Centre. “The important message is to recognise the wickedness of the problem that humanity faces.”
When the Arctic ice sheets melt, there is less ice to reflect the sun’s heat so the temperature of the planet rises. This increases the risks of forest fires, which discharge carbon into the air that adds to the greenhouse effect, which melts more ice. Although geographically distant, each amplifies the other.
The deforestation of the Amazon is responsible for multiple “cascading effects” – weakening rain systems, forests becoming savannah, and reduced water supplies for cities like São Paulo and crops in the foothills of the Andes. This, in turn, increases the pressure for more land clearance.
Until recently, the study of tipping points was controversial, but it is increasingly accepted as an explanation for climate changes that are happening with more speed and ferocity than earlier computer models predicted. The loss of coral reefs and Arctic sea ice may already be past the point of no return. There are signs the Antarctic is heading the same way faster than thought.
“We’re surprised at the rate of change in the Earth system. So much is happening at the same time and at a faster speed than we would have thought 20 years ago. That’s a real concern,” said co-author Garry Peterson. “We’re heading ever faster towards the edge of a cliff.”