Has the Amazon Reached Its ‘Tipping Point’?
In the past half-century, 17 percent of the Amazon —
an area larger than Texas — has been converted to croplands or cattle pasture.
Less forest means less recycled rain, less vapor to cool the air, less of a
canopy to shield against sunlight. Under drier, hotter conditions, even the
lushest of Amazonian trees will shed leaves to save water, inhibiting
photosynthesis — a feedback loop that is only exacerbated by global warming.
According to the Brazilian Earth system scientist
Carlos Nobre, if deforestation reaches 20 to 25 percent of the original area,
“flying rivers” — rain clouds that recycle the forest’s own moisture five or
six times — will weaken enough that a rainforest simply will not be able to
survive in most of the Amazon Basin. Instead it will collapse into scrubby
savanna, possibly in a matter of decades.
Losing the Amazon, one of the most biodiverse
ecosystems on Earth, would be catastrophic for the tens of thousands of species
that make their home there. What scientists are most concerned about, though,
is the potential for this regional, ecological tipping point to produce
knock-on effects in the global climate.
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