Space & Innovation

Amazon Deforestation Could Cause Extreme Droughts

Cutting down wide swaths of forests could reduce rainfall in South America dramatically by 2050. →

Since 1970, humans have cut down about 20 percent of the Amazon rain forest in South America. Though the pace of deforestation had slowed in recent years, it's now picking up again, thanks to an improved global economy that's boosted demand for farmland, and recently-enacted Brazilian laws and policies that promote development of the wild.

But if we revert to the aggressive rates of deforestation seen in the mid-2000s, the denuded Amazon eventually is going to exact a vengeance of the people who caused it - and a lot of others in South America, in the form of punishing long-term drought.

That's the takeaway from a new study published in Geophysical Research Letters, a journal of the American Geophysical Union. It predicts that by the mid-21st Century, the Amazon basin, which covers 40 percent of South America's land mass, will suffer a devastating drop in precipitation. The projected norm for annual rainfall actually will be less than the region currently receives during drought years.

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"Maintaining low deforestation rates in the Amazon is essential to ensure survival of the Amazon forest," said lead author Dominick Spracklen, an atmospheric scientist at the University of Leeds in Great Britain, in a press release.

Destroying trees creates a water problem because trees are an important factor in regulating the exchange of water, energy and gases between the Earth's surface and the atmosphere. Cutting down forests can alter local temperature, humidity and rainfall, though the results are tricky to forecast. To do so, the study's authors did a meta-analysis of 96 different models.

The Amazon already is showing signs of water distress. A study published in Proceedings of the National Academy of Sciences in 2014 reported that precipitation has decreased 25 percent since 2000 over a wide swath of the southeastern Amazon, and that vegetation in that area has suffered from the drying out.

Photos Capture Some of the Oldest Trees on Earth

The cutting down of the Amazon began in earnest in the early 1970s, when construction of the Trans-Amazonian Highway made the nation's interior accessible to cattle ranchers and farmers who wanted land. By 2004, the frenzy of tree-cutting and burning peaked, and 6.7 million acres of forest were wiped out. After hearing dire predictions about the Amazon's future, lawmakers enacted new rules that reduced forest clearing rates to about a quarter of the 2004 rate.

The rainfall reductions could have catastrophic effects upon Brazilian agriculture, which generates about $15 billion in income. Decreased flow in waterways also could interfere with the hydropower plants that generate 65 percent of the nation's electricity.

But South America won't be the only place that could suffer from the Amazon's destruction, according to the study. The rain forest plays a crucial role in the entire planet's carbon cycle, so there could be impacts upon global climate and weather as well.

Slash-and-burn land clearing in the Colombian portion of the Amazon rain forest.

Rachel Sussman spent a decade working with biologists and traveling the globe to photograph continuously living organisms that are 2,000 years old and older. She traveled to remote locations from Greenland to Antarctica, Africa and Australia for her book

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The Oldest Living Things in the World

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Above, bristlecone pines are the oldest unitary organisms in the world, known to surpass 5,000 years in age. In the 1960s a then-grad student cut down what would have been the oldest known tree in the world while retrieving a lost coring bit. A cross section of that tree was placed in a Nevada casino.

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This critically endangered eucalyptus is around 13,000 years old, and one of fewer than five individuals of its kind left on the planet. The species name might hint to heavily at its location, so it has been redacted.

What looks like moss covering rocks is actually a very dense, flowering shrub that happens to be a relative of parsley, living in the extremely high elevations of the Atacama Desert.

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This 5,500-year-old moss bank lives right around the corner from where the Shackleton Expedition was marooned 100 years ago on Elephant Island, Antarctica. It was a victory simply being able to locate it. These days it's easier to get to Antarctica from space.

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At 100,000 years old, the Posidonia sea grass meadow was first taking root at the same time some of our earliest ancestors were creating the first known “art studio” in South Africa. It lives in the UNESCO-protected waterway between the islands of Ibiza and Formentera.

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This 9,950-year-old tree is like a portrait of climate change. The mass of branches near the ground grew the same way for roughly 9,500 years, but the new, spindly trunk in the center is only 50 or so years old, caused by warming at the top of this mountain plateau in Western Sweden.

Living Fossils: Animals From Another Time