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Catastrophic Amazon tipping point less than 30 years away: study

  • The Amazon rainforest generates half its own rainfall, but deforestation threatens to disrupt this cycle, shifting large parts of this ancient forest to dry, savanna habitat. Passing such a “tipping point” would have disastrous knock-on effects for climate and weather patterns regionally and globally.
  • A recent study modelling the impact of proposed roads, hydropower and mining developments in the Amazon basin suggests that 21-43 percent of the Amazon’s original extent will be lost by 2050, putting it close to, or beyond, the tipping point for a biome shift in large parts of the region.
  • Although development is not currently proceeding at the rapid rate predicted under various ambitious government initiatives, experts say that, even with no new Amazon infrastructure, continued deforestation could drive the biome to the tipping point in the next 15–30 years.
  • A quick transition to zero deforestation is the only way to avert catastrophic change to the Amazon, say experts. But conservationists fear the political will is lacking as the Bolsonaro administration continues to slash protections. Backing indigenous land stewards could offer a solution.
The Amazon supplies half its own rainfall through evaporation and transpiration from trees, but scientists warn that this cycle may be changing, bringing dryer times. If deforestation continues, an altered climate could convert rainforest to savanna. Image courtesy of International Rivers.

One of the most important questions Amazon scientists are asking today is, how much deforestation and global climate change can this tropical biome tolerate before rainfall is drastically reduced — forcing a rainforest-to-savanna conversion, and releasing huge amounts of stored forest carbon into the atmosphere in the process?

A recent study tried to answer that question. The findings: the Amazon basin could be less than 30 years from a catastrophic collapse that would turn it into a dry savanna, according to a study published in the journal One Earth.

For many centuries, vast amounts of evaporation and transpiration from Amazon trees generated around half of the biome’s own annual rainfall — a regional cycle that interacts with atmospheric circulation to sustain the Amazon’s characteristically moist climate. But as global climate change has intensified, conservationists and climatologists have expressed concerns that there may be a threshold of deforestation beyond which the cycle would not longer sustain itself. In this scenario, large parts of the drying basin may shift into a savanna biome, with knock-on consequences for climate and weather patterns across the South American continent and globally.

Early estimates suggested that this “tipping point” might lie at around 40% deforestation. But in 2018, noted Amazon climatologist Carlos Nobre and conservation biologist Thomas Lovejoy revised this estimate, warning that the synergistic effects of climate change, drought and wildfires could bring the tipping point much closer — between 20 and 25% deforestation.

The present study, led by Robert Walker at the University of Florida, Gainesville, combined projections of future agricultural expansion published by Brazil’s Ministry of Agriculture, Livestock and Food Supply (MAPA) and the Food and Agricultural Organization of the United Nations (FAO), along with plans for the region’s industrial and infrastructure development, in order to estimate the total area of the Amazon basin that could be deforested by 2050.

They found that agricultural expansion and infrastructure development over the next thirty years could put the Amazon rainforest well beyond the tipping point for shifting to a savanna biome.

The researchers included in their model the road, hydropower and mining projects planned as part of the Initiative for the Integration of the Regional Infrastructure of South America (IIRSA), a multinational agreement made between 12 South American countries in 2000. IIRSA has been heavily criticized by conservationists for its potential to drive large-scale Amazon deforestation.

New hydropower dams, mines, and the roads that enable their construction, do direct environmental harm to the immediate areas around which they’re built, but their indirect effects are often even more severe. “The relationship between roads and deforestation is 1-to-1… within 10 years of opening a road you have… 20 kilometers [12.5 miles] on each side of the road, heavily deforested,” said Nobre, who was not involved in the present study. If that road is paved, he added, that area doubles. Such projects attract large numbers of workers who relocate, often permanently, to newly built up areas on the Amazon frontiers, driving further deforestation.

The massive Amazon infrastructure plan known as IIRSA, the Initiative for the Integration of the Regional Infrastructure of South America, including existing and planned dams, ports, roads, railroads and industrial barge routes. The map also identifies known mineral deposits in Legal Amazonia. The large rectangle in the middle identifies the Tapajós River Valley, proposed for major development. Image courtesy of Walker, R. T. et al.

In the study’s worst-case scenario, in which agricultural expansion is high and environmental governance is weak, the new model projects over 1 million square kilometers (386,102 square miles) of deforestation by 2050.

By comparison, a best-case scenario where cattle ranching intensification on already degraded lands minimizes a need for pasture expansion, and where there is strong government enforcement of environmental protections, just 92,500 square kilometers (35,714 square miles) of deforestation would occur.

Taking into account deforestation that has already happened, and adding on estimated tree loss driven by new infrastructure, 21–43% deforestation of the Amazon’s original area could occur by 2050, which experts say could be enough to push the biome past it’s tipping point. (It’s important to understand that biome tipping points can only be fully recognized and precisely pinpointed in time after they happen, not before or while they are underway.)

Nobre had a little good news for the Amazon and the global climate, in that the massive infrastructure development plans like those represented by IIRSA are unlikely to materialize as quickly or fully as projected, based on current construction trends. “When we look at the way infrastructure development is unfolding in the Amazon, that’s not really the way it’s going,” he said.

But even with zero new Amazon infrastructure development, Nobre said that the biome will continue to move closer and closer to the tipping point. “I do not want to give the impression that if we are able to get new infrastructure to zero, then we save the Amazon, because the infrastructure to exceed the tipping point is there already,” he explained. To avoid the tipping point entirely, “we have to drive deforestation to zero, and that really is a different ballgame.”

This figure portrays the deforestation generated by each of the study’s scenarios in the year 2050. The worst-case (upper panel) spatially distributes a projected forest loss of 43% across the Brazilian Amazon. The lower panel does the same for the best case, with a 21% forest loss. Image courtesy of Walker, R. T. et al.

Zeroing in on the tipping point

Nobre and Lovejoy believe the Amazon is already very close to the tipping point, with the first possible signs of the transition already being observed on the ground. Nobre estimates we have between 20 and 25 years, if the 2018 deforestation rate were to be maintained. But if the surges in deforestation seen in 2019 continue, the tipping point could be as little as 15 years away.

However, a recent policy briefing by Monica de Bolle, an economist at the Peterson Institute for International Economics in Washington, D.C. claims the situation is even more dire — she believes the tipping point could be as little as two years away.

Scientists disagree, saying that her calculations are unrealistic. “The numbers de Bolle presents are highly unlikely,” said Walker. De Bolle projects 42,994 square kilometers (16,600 square milesof deforestation in 2021, more than double the highest annual loss ever recorded. “There is simply no way this will happen,” Walker said.

Furthermore, the 20–25% deforestation tipping point threshold put forward by Nobre and Lovejoy takes into account substantial climate warming that leads to a spiraling positive feedback loop, which Walker contends has not come into play as yet. “Although drought has intensified in the Amazon basin since the mid-1980s, it has not done so to the extreme,” Walker said.

De Bolle disagrees. As Amazon deforestation progresses, she said, “it creates its own patterns of self-destruction,” which she believes are already starting to take effect, citing “unprecedented” droughts in 2005, 2010 and 2016 that “would seem to signal that these changing weather patterns are already happening.”

Such severe projections are a warning against complacency, de Bolle added. “Whether the numbers are exactly right or not, it’s a very important debate to have because it means we can’t really waste any more time.”

Deforestation has soared in the Brazilian Amazon since President Jair Bolsonaro took office last January. According to satellite data released by the Brazilian National Institute for Space Research (INPE) in November, deforestation in Brazil’s Legal Amazonia has increased by nearly 30% in the last year, with 9,762 square kilometers (3,769 square miles) cleared between August 2018 and July 2019.

The extent of the Amazon biome (which touches seven nations) and Amazonia Legal (a Brazilian political designation). Also indicated are the two biomes that now occupy the basin, the Amazon rainforest biome and the Cerrado tropical savanna biome. Climate change, deforestation and fire could all combine to convert large portions of forest to savanna over the next thirty years. Image courtesy of Walker, R. T. et al.

A lack of political will

Recent increases in deforestation must be reversed, say scientists, to have any hope of avoiding an Amazon biome tipping point. In the past, Brazil has succeeded in significantly curbing deforestation rates, but experts question whether there’s now the political will to halt the current trend. “Deforestation is very unlikely to be reduced in the next three or four years,” said Nobre.

The same underlying problem is at play across the Amazon basin, he added, as Amazon nations support policies that favor historical development interests.

If the Brazilian government continues to promote agribusiness expansion it could be catastrophic for the Amazon and the world, said Walker: “If development proceeds for another 5–10 years with no controls there’s really no hope.”

Pressure from international governments could help trigger a change, but such pressure needs to be constructive not critical, said de Bolle. “I think the kind of response that’s needed is… ‘let us know what you need and we’re here for you’… [that approach] is likelier to lead to constructive engagement.”

Sustained pressure from the media and global consumers is also likely needed to create economic incentives to persuade Brazil’s agribusiness sector that it is more profitable to protect the Amazon than to plunder it. “People need to really get active… I don’t think it’s necessarily writing your congress person, I think it’s protest and boycott and vociferous agitation,” that will be effective, added Walker.

The Munduruku indigenous group held successful protests against the planned construction of the São Luiz do Tapajós hydroelectric mega-dam that would have flooded indigenous land in Pará state, Brazil. Image found on Flickr. https://www.flickr.com/photos/rochadomarcio/19792170219/in/album-72157655893319240/ (CC by 2.0 by Márcio Monteiro Rocha)

The role of indigenous communities

The new study proposes that if remaining forest is to be conserved, then indigenous communities have a crucial role to play. The Munduruku in Brazil’s Tapajós basin, for example, successfully reversed government plans for the construction of a huge hydropower development in Pará state.

When the São Luiz do Tapajós hydroelectric dam threatened to flood their land and do major ecological damage, the Munduruku took matters into their own hands. After waiting many years for Brazil’s National Indian Foundation (FUNAI) to officially recognize its Sawré Muybu territory in an unpublished report that would help protect it from the proposed dam, the group decided to mark out the boundaries with a 4-meter wide clearing and signs that imitated the governments’ own.

They also organized protests that captured the attention of the international media, and by August 2016 the pressure on Brazilian authorities became too much; construction of the dam was cancelled. Time and again, it has been proven that indigenous groups are the Amazon’s best forest stewards.

One of the biggest challenges faced by groups trying to protect indigenous lands is the lack of clarity over land rights across the Brazilian Amazon — ambiguity that can allow for land theft by rural elites. Therefore, to support indigenous groups like the Munduruku, “the global community could really put pressure on the Brazilian government to clarify exactly what their constitutional rights are… [that] would give indigenous peoples a very strong institutional weapon to defend their territorial rights,” said Walker. But instead, at the end of 2019 the Bolsonaro government issued an executive decree making it far easier for land grabbers to legitimize their land claims within indigenous reserves.

“The indigenous people have been the most important communities for conservation because they value the forest as a cultural value [and] their livelihoods depend on the forest, traditionally for millennia,” said Nobre.

As an alternative to infrastructure development, the researcher recently proposed the Amazon 4.0 project to keep the forests standing based on a sustainable bioeconomy for Brazil, which he says would offer indigenous and traditional communities new tools that would support them to “harness all those biological assets of the forest… in a way that [their traditional knowledge] can mean better livelihoods for them.”

Localized renewable energy, for example, including solar panels and instream turbines, could bring electricity to remote Amazonian communities without disrupting the forest ecosystem with hydroelectric dams or transmission lines, leaving communities, culture and traditions — as well as forests — intact.

Indigenous communities “will be much more empowered to defend their livelihoods [and] the forest if they become… part of a sustainable bioeconomy,” Nobre concluded.

Banner image caption: Brazil’s Cerrado tropical savanna biome, located east and south of the Amazon biome, could offer a glimpse of what large parts of the Amazon may look like if deforestation exceeds the predicted tipping point. Photo credit: Christoph Diewald on Visualhunt.com / CC BY-NC-ND

Citation:

Walker, R. T., Simmons, C., Arima, E., Galvan-Miyoshi, Y., Antunes, A., Waylen, M., & Irigaray, M. (2019). Avoiding Amazonian Catastrophes: Prospects for Conservation in the 21st Century. One Earth1(2), 202-215. DOI: 10.1016/j.oneear.2019.09.009

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