Risks of 'domino effect' of tipping points greater than thought, study says

https://www.theguardian.com/environment/2018/dec/20/risks-of-domino-effect-of-tipping-points-greater-than-thought-study-says

Jonathan Watts
Thu 20 Dec 2018 14.00 EST
Last modified on Thu 20 Dec 2018 14.01 EST

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.
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“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.”

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Among the latter pairings were Arctic ice sheets and boreal forests. When the former 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.

By contrast, a one-way domino-type impact is that between coral reefs and mangrove forests. When the former are destroyed, it weakens coastal defences and exposes mangroves to storms and ocean surges.

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.

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Co-author Garry Peterson said the tipping of the west Antarctic ice shelf was not on the radar of many scientists 10 years ago, but now there was overwhelming evidence of the risks – including losses of chunks of ice the size of New York – and some studies now suggest the tipping point may have already been passed by the southern ice sheet, which may now be releasing carbon into the atmosphere.

“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 Peterson. “We’re heading ever faster towards the edge of a cliff.”

•••••

Co-author Garry Peterson said the tipping of the west Antarctic ice shelf was not on the radar of many scientists 10 years ago, but now there was overwhelming evidence of the risks – including losses of chunks of ice the size of New York – and some studies now suggest the tipping point may have already been passed by the southern ice sheet, which may now be releasing carbon into the atmosphere.

“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 Peterson. “We’re heading ever faster towards the edge of a cliff.”

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“It’s a little depressing knowing we are not on a trajectory to keep our ecosystem in a functional state, but these connections are also a reason for hope; good management in one place can prevent severe environmental degradation elsewhere. Every action counts.”