By Chris Lang
In September 2007, a paper by a group of Brazilian researchers was published in Geophysical Research Letters. The title was “Regional climate change over eastern Amazonia caused by pasture and soybean cropland expansion”.
The opening line of the paper explains that,
Field observations and numerical studies revealed that large scale deforestation in Amazonia could alter the regional climate significantly, projecting a warmer and somewhat drier post-deforestation climate.
The researchers looked at a business-as-usual scenario of deforestation that involved the clearing of the rainforest to make way for cattle ranching and soy plantations. They found that air temperatures in eastern Amazonia would increase, and rainfall would decrease.
In 2007, when the paper was written, about 15% of the Brazilian Amazon had been deforested, largely due to cattle ranching and agriculture. The expansion of soy plantations played “a major role in the last few years” the researchers write.
The authors predict that if current deforestation trends continued, about 40% of Amazon forests would be destroyed by 2050. Large areas of the Amazon have soils, climate and topography that are suitable for industrial agriculture.
The authors write that,
The Amazon has entered a new era as the growing profitability of cattle ranching and soy production increases deforestation rates and drives the expansion of the highway network into the region’s core.
They conclude with a dire warning:
The reduction in precipitation can create favorable conditions to potentially alter the structure of the forests, and lead to a process of savannization . . . .
One of the papers they cite to back up this statement was written in 1991. That paper, titled “Amazonian Deforestation and Regional Climate Change” points out that deforestation could lead to a longer dry season in the southern Amazon, “which could have serious implications for the reestablishment of the tropical forests following massive deforestation since rainforests only occur where the dry season is very short or nonexistent”.
Amazon tipping point
In February 2018, Thomas Lovejoy and Carlos Nobre published an editorial in the journal Science Advances. Nobre is one of the authors of the 2007 paper – and the 1991 paper. Nobre is a Member of the Brazilian Academy of Sciences and Senior Fellow of World Resources Insitute Brazil. Lovejoy is University Professor in the Department of Environment Science and Policy at George Mason University. He’s worked in Brazil’s Amazon since 1965.
In their editorial, Lovejoy and Nobre note that the Amazon generates about half of its own rainfall. Moisture is recycled five to six times as the air moves over the Amazon basin from the Atlantic towards the Andes in the west.
Lovejoy and Nobre ask the tipping point question: “[H]ow much deforestation would be required to cause the cycle to degrade to the point of being unable to support rain forest ecosystems”?
The 2007 paper that Nobre co-authored showed that “at about 40% deforestation, central, southern and eastern Amazonia would experience diminished rainfall and a lengthier dry season, predicting a shift to savanna vegetation to the east”.
In 2018, Lovejoy and Nobre write that,
We believe that the negative synergies between deforestation, climate change, and widespread use of fire indicate a tipping point for the Amazon system to flip to non-forest ecosystems in eastern, southern and central Amazonia at 20-25% deforestation.
They note that the serious droughts in 2005, 2010, and 2015-2016 “could well represent the first flickers of this ecological tipping point”. Severe floods in 2009, 2012 (and 2014 in southwest Amazonia) “suggest that the whole system is osciallating”.
The dry season in the southern and eastern Amazon has been increasing for the past two decades.
Lovejoy and Nobre argue that the deforested area should be kept to less than 20%, because “there is no point discovering the precise tipping point by tipping it”.
The tipping point is here
In December 2019, Lovejoy and Nobre wrote another editorial in Science Advances.
“Although 2019 was not the worst year for fire or deforestation in the Amazon, it was the year when the extent of fires and deforestation in the region garnered full global attention,” they write.
When rain falls on the Amazon rainforest, at least 75% of the moisture returns to the atmosphere. When the forest is destroyed, more than 50% of the rainwater runs off and is not available to recycle.
“Current deforestation is subtantial and frightening,” Lovejoy and Nobre write. “17% across the entire Amazon basin and approaching 20% in the Brazilian Amazon.”
Dry seasons are hotter and longer. Wet climate tree species are dying in greater number. Dry climate species are showing resilience.
The editorial is not written in a dry academic style: “The precious Amazon is teetering on the edge of functional destruction and, with it, so are we.”
The authors conclude that “The tipping point is here, it is now.”
In their 2019 editorial, Lovejoy and Nobre call for a “new vision of the Amazon” that would exclude “illogical and short-sighted economies such as the unreliable mono-cutures of cattle, soybeans, and sugarcane”.
So far so good. But Lovejoy and Nobre also argue that a major reforestation project is “the only sensible way forward” especially in the southern and eastern Amazon. They don’t mention the problem, raised in the paper Nobre co-authored in 1991, of re-establishing rainforest in a climate with a longer dry season.
They say nothing about what species of trees would make sense – and which would be problematic. They do not discuss, for example, the problems created by eucalyptus monocultures in Brazil, particularly for communities living near them.
The authors make no mention of land rights, indigenous peoples’ rights, or climate justice.
Lovejoy and Nobre also suggest that reforestation would “qualify Brazilian states for support under the new California Tropical Forest Standard, which allows states not only to get financial support from carbon-capped California companies but could also bring positive attention to the country and draw support and assistance from the rest of the world”.
Unfortunately, Lovejoy and Nobre make no mention of the fact that carbon trading schemes, such as California’s, do not actually reduce greenhouse gas emissions. The climate crisis means that forest fires are more likely and occur more frequently. And generating carbon offsets from reforestation in Brazil would guarantee continued emissions from burning fossil fuels in California. The result? More global heating. More forest fires.
Lovejoy and Nobre also propose that,
A modern vision of the Amazon must include truly innovative elements to create profitable bioeconomies through, for example, sensible use of intact forests, the harnessing of power from its massive flowing rivers, or the sustainable harvesting of biological and biomimetic assets within Amazonian biodiversity.
It isn’t at all clear what “sensible use of intact forests” might entail. The history of logging in the Amazon, whether under the guise of “sustainable forest management” or not has been disastrous for the forests, for the climate, and for the indigenous peoples who live there.
Lovejoy and Nobre do not discuss the enormous environmental and social impacts of hydropower dams in the Amazon basin. Brazil is currently carrying out a dam-building boom. In a 2017 article for Yale Environment 360, Philip Fearnside, an ecologist at the National Institute for Research in Amazonia (INPA) in Brazil, describes the impacts as follows:
Brazil is in the midst of a dam-building spree in the Amazon basin that is changing the face of the world’s largest tropical forest region. The boom is driven by the country’s agricultural and heavy industrial interests, is being carried out with little regard to the impacts on indigenous people and the environment, is proceeding with little effort to capitalize on the nation’s vast renewable energy potential, and is often fueled by corruption.
And Lovejoy and Nobre make no mention of the dangers of biopiracy – the stealing of indigenous knowledge for the profit of multinational pharma corporations.
Lovejoy and Nobre are obviously correct to raise the alarm about deforestation in the Amazon. And they are no doubt correct that we are rushing headlong towards a tipping point where the Amazon rainforest ecosystem will flip, resulting in vast losses of biodiversity and carbon.
But the “solutions” they are proposing will only end up exacerbating the problem.