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Amazon rain forest near tipping point?

| Updated: November 28, 2021 10:50:39

Amazon rain forest near tipping point?

Some scientists fear we are nearing a point of no return in the Amazon rainforest, which exerts power over the carbon cycle like no other terrestrial ecosystem on Earth. Evidence is mounting that in certain areas, localized iterations of irreversible damage may already be happening. Reuters has tracked three decades-long observations of the region to give a real-world view of degradation once only predicted by computer simulations.

Gertrudes Freire and her family came to the great forest in search of land and rain. They found both in abundance on that day half a century ago, but the green wilds of the southwestern Amazon would prove tough to tame.

When they reached the settlement of Ouro Preto do Oeste in 1971, it was little more than a lonely rubber-tapper outpost hugging the single main road that ran through the jungle like a red dust scar.

Sitting on the porch of the family farmhouse in the sweltering heat of the Amazon dry season, Gertrudes, now 79 with neat gray hair tucked behind her ears and a smile that shows half a dozen stubborn teeth, recalls the hardship and hope.

Her children remember the fear. Fear of forest jaguars, indigenous tribes and the mythological Curupira: a creature with backward-turned feet who misleads unwelcome visitors to leave them lost among the trees.

The family carved their home from the forest. They built their walls from the tough trunks of the cashapona tree and thatched a leaky roof from the broad palms of the babassu. There was no electricity, and some days the only food was foraged Brazil nuts. At night, in hungry darkness they would listen to the cascading rain. Life was damp.

Until it wasn’t.

Near the Freire home, there was a stream so wide that the children – aged between 5 and 12 when they arrived – would dare each other to reach the other side. They called it Jaguar’s Creek. Now it’s not a meter wide and can be cleared with a single step.

The loss of such streams, and the wider water problems they are a part of, fill scientists with foreboding.

Covering an area roughly the size of the contiguous United States and accounting for more than half of the world’s rainforest, the Amazon exerts power over the carbon cycle like no other terrestrial ecosystem on Earth. The tree loss from an extremely dry year in 2005, for example, released an additional quantity of carbon dioxide into the atmosphere equivalent to the annual emissions of Europe and Japan combined, according to a 2009 study published in Science magazine.

As more and more of the forest is cut down, researchers say the loss of canopy risks hitting a limit – a tipping point – after which the forest and local climate will have changed so radically as to trigger the death of the Amazon as rainforest. In its place would grow a shorter, drier forest or savannah.

The Amazon tipping point would mark a final shift in the rainforest’s ability to sustain itself.

The consequences for biodiversity and climate change would be devastating, extinguishing thousands of species and releasing such a colossal quantity of carbon dioxide into the atmosphere that it would sabotage attempts to limit global climate change.

The Amazon tipping point would mark a final shift in the rainforest’s ability to sustain itself, an inflection point after which the trees can no longer feed traversing clouds with enough moisture to create the quantities of rain required to survive.

Climate models have foreseen other so-called tipping points disrupting Earth’s long-balanced systems, for example warming that causes Siberian permafrost to thaw and release huge amounts of emissions, or Greenland’s Ice Sheet melting at such a rate that annual snowfall can no longer make up for the loss.

Exactly where that point is in the Amazon, science is not yet decided. Some researchers argue that current modeling isn’t sophisticated enough to predict such a moment at all. But evidence is mounting that in certain areas, localized iterations of the tipping point may already be happening.

Reuters has tracked three extended experiences of the Amazon to give a real-world view of degradation once only predicted by computer simulations.

A family that has farmed this once-lush part of rainforest for almost 50 years. A scientist couple who have monitored thousands of individual trees for decades. And an atmospheric chemist who has collected air samples from far above the canopy for years. Their perspectives reveal the long-term impact of deforestation: on rainfall, on the remaining forest and on global emissions. Taken together, they show the dangerous extent of the changes wrought on the world’s largest rainforest, and a possible glimpse of things to come.

Even as science learns more about the far-reaching impact of destruction that began many years or even decades ago, deforestation has surged under President Jair Bolsonaro, who supports further opening the Amazon for mining and agriculture. Last year, an area larger than Lebanon was cut from the rainforest, and though preliminary data for 2021 points to a slight year-on-year decline, deforestation remains at a level not seen in Brazil since 2008.

Ecologist Paulo Brando, one of the leading scientists studying the changing health of the Amazon rainforest, sums it up: “There’s a limit to how much shit the system can take.”

Year after year, the Freire family hacked and sawed farther into their patch of forest on Brazil’s western frontier.

In 1976, after clearing a couple of hectares and getting permission to use some of their neighbor’s pasture too, they invested in 10 heifer calves and a bull – the start of a dairy business that would over the years grow into a successful herd of about 400 head.

But a fear of drought haunted their work. They had come from the Vale do Jequitinhonha, 2,500 kilometers (1,553 miles) to the east, where decades of slash-and-burn agriculture had dried and degraded the land, plunging its people into poverty. The semi-arid strip became notorious as the “Valley of Misery.” Even while water was plentiful, they sensed the same could happen in their new home.

Soil erosion, like that which plagued the Vale do Jequitinhonha, often follows rapid and chaotic agricultural expansion. Land stripped of native vegetation, especially when transformed into pasture and pounded hard by grazing cattle, loses ability to retain water in soil and foliage. Rain runs off the altered surface in sudden surges, dragging topsoil into streams and rivers that then clog and dry.

Brazil is blessed with the largest freshwater reserves in the world. But the relentless rise of one of the world’s agricultural powerhouses combined with changes in global climate are helping to drive a loss of this vital resource. Data released this year by MapBiomas, a collaboration between universities, nonprofit groups and technology companies, found Brazil lost 15% of its surface water in the three decades prior to 2020, reports Reuters.

For the Freires, the last bits of doubt about the drying of the land seeped away on a parched day in 1991. A cowhand told Gertrudes the cattle were so thirsty, they were nuzzling the bottom of dried-out springs, sucking the sand in search of moisture.

She acted swiftly and put in a complex system of pipes and pumps to draw water for the cattle from springs that had not yet gone dry.

Controversially, she began reforesting too. Gertrudes had little idea of what she was doing but trusted her instincts, sharpened by years of drought in the homeland she’d abandoned.

Her neighbors – and husband – thought she was crazy as she planted trees around water sources and along streams and vowed that the last remaining patch of virgin forest, at the far end of the property, should remain intact.

Her words weren’t always heeded. “I came back from one short trip away and my husband had cleared another patch” for pasture, she remembers, shaking her head.

Gertrudes sensed that rainfall was changing too.

Several scientific studies have found the same. Because tropical forests influence rainfall, deforestation can change their pattern. One influential 2011 paper looking at 30 years of precipitation data found that the onset of rains in Rondonia state, where the family lives, had been delayed by up to 18 days.


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