Top scientists warn of an Amazon ‘tipping point’

Top scientists warn of an Amazon ‘tipping point’

SOURCE: Washington Post DATE: December 20, 2019 SNIP: Deforestation and other fast-moving changes in the Amazon threaten to turn parts of the rainforest into savanna, devastate wildlife and release billions of tons carbon into the atmosphere, two renowned experts warned Friday. “The precious Amazon is teetering on the edge of functional destruction and, with it, so are we,” Thomas Lovejoy of George Mason University and Carlos Nobre of the University of Sao Paulo in Brazil, both of whom have studied the world’s largest rainforest for decades, wrote in an editorial in the journal Science Advances. “Today, we stand exactly in a moment of destiny: The tipping point is here, it is now.” Combined with recent news that the thawing Arctic permafrost may be beginning to fill the atmosphere with greenhouse gases, and that Greenland’s ice sheet is melting at an accelerating pace, it’s the latest hint that important parts of the climate system may be moving toward irreversible changes at a pace that defies earlier predictions. In interviews, Lovejoy and Nobre said they decided to sound a dire alarm about the Amazon after witnessing the acceleration of troubling trends. The combination of rising temperatures, crippling wildfires and ongoing land clearing for cattle ranching and crops has extended dry seasons, killed off water-sensitive vegetation and created conditions for more fire. The Amazon is 17 percent deforested, but for the large portion of it inside Brazil, the figure is closer to 20 percent. The fear is that soon there will be so little forest that the trees, which not only soak up enormous quantities of rainwater but also give off mist...
Climate tipping points — too risky to bet against

Climate tipping points — too risky to bet against

SOURCE: Nature DATE: November 27, 2019 SNIP: Politicians, economists and even some natural scientists have tended to assume that tipping points1 in the Earth system — such as the loss of the Amazon rainforest or the West Antarctic ice sheet — are of low probability and little understood. Yet evidence is mounting that these events could be more likely than was thought, have high impacts and are interconnected across different biophysical systems, potentially committing the world to long-term irreversible changes. Here we summarize evidence on the threat of exceeding tipping points, identify knowledge gaps and suggest how these should be plugged. We explore the effects of such large-scale changes, how quickly they might unfold and whether we still have any control over them. The Intergovernmental Panel on Climate Change (IPCC) introduced the idea of tipping points two decades ago. At that time, these ‘large-scale discontinuities’ in the climate system were considered likely only if global warming exceeded 5 °C above pre-industrial levels. Information summarized in the two most recent IPCC Special Reports (published in 2018 and in September this year) suggests that tipping points could be exceeded even between 1 and 2 °C of warming. If current national pledges to reduce greenhouse-gas emissions are implemented — and that’s a big ‘if’ — they are likely to result in at least 3 °C of global warming. This is despite the goal of the 2015 Paris agreement to limit warming to well below 2 °C. Some economists, assuming that climate tipping points are of very low probability (even if they would be catastrophic), have suggested that 3 °C warming is optimal from a cost–benefit perspective. However,...
Amazon rainforest ‘close to irreversible tipping point’

Amazon rainforest ‘close to irreversible tipping point’

SOURCE: The Guardian DATE: October 22, 2019 SNIP: Soaring deforestation coupled with the destructive policies of Brazil’s far-right president, Jair Bolsonaro, could push the Amazon rainforest dangerously to an irreversible “tipping point” within two years, a prominent economist has said. After this point the rainforest would stop producing enough rain to sustain itself and start slowly degrading into a drier savannah, releasing billions of tonnes of carbon into the atmosphere, which would exacerbate global heating and disrupt weather across South America. The warning came in a policy brief published this week by Monica de Bolle, a senior fellow at the Peterson Institute for International Economics in Washington DC. The report sparked controversy among climate scientists. Some believe the tipping point is still 15 to 20 years away, while others say the warning accurately reflects the danger that Bolsonaro and global heating pose to the Amazon’s survival. “It’s a stock, so like any stock you run it down, run it down – then suddenly you don’t have any more of it,” said De Bolle. The policy brief noted that Brazil’s space research institute, INPE, reported that deforestation in August was 222% higher than in August 2018. Maintaining the current rate of increase INPE reported between January and August this year would bring the Amazon “dangerously close to the estimated tipping point as soon as 2021 … beyond which the rainforest can no longer generate enough rain to sustain itself”, De Bolle wrote. Carlos Nobre, one of Brazil’s leading climate scientists and a senior researcher at the University of São Paulo’s Institute for Advanced Studies, questioned her calculation that estimated deforestation...
Amazon deforestation accelerating towards unrecoverable ‘tipping point’

Amazon deforestation accelerating towards unrecoverable ‘tipping point’

SOURCE: The Guardian DATE: July 25, 2019 SNIP: Deforestation of the Brazilian Amazon has surged above three football fields a minute, according to the latest government data, pushing the world’s biggest rainforest closer to a tipping point beyond which it cannot recover. The sharp rise – following year-on-year increases in May and June – confirms fears that president Jair Bolsonaro has given a green light to illegal land invasion, logging and burning. Clearance so far in July has hit 1,345 sq km, a third higher than the previous monthly record under the current monitoring system by the Deter B satellite system, which started in 2015. The steady erosion of tree cover weakens the role of the rainforest in stabilising the global climate. Scientists warn that the forest is in growing danger of degrading into a savannah, after which its capacity to absorb carbon will be severely diminished, with consequences for the rest of the planet. “There are a number of tipping points which are not far away,” said Philip Fearnside, a professor at Brazil’s National Institute of Amazonian Research. “We can’t see exactly where they are, but we know they are very close. It means we have to do things right away. Unfortunately that is not what is happening. There are people denying we even have a...
Risks of ‘domino effect’ of tipping points greater than thought, study says

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

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...