Who will save the wonders of the Amazon, and with them the climate? Part 4 – At the threshold

Biodiversity and carbon are not the only reasons we need the Amazon. But whether we look at water, air, forests, economic development and urbanization in the Amazon, and the consequences of changes there for the rest of the world, somewhere in the story of the Amazon’s life cycle we always end up with these two: biodiversity and carbon, and their intimate relationship.

Since 2015, in the Uatumã Nature Reserve, one hundred and fifty kilometers northeast of the Brazilian Amazon city of Manaus, a three-hundred-and-twenty-five-meter steel research tower has risen like a needle out of the tropical rainforest. It is the tallest climatological tower in the world, taller than the Eiffel Tower. Next to it are two other towers, each eighty meters high.

The Amazon Tall Tower Observatory, or ATTO for short, is an “atmospheric laboratory” built to understand how the Amazon rainforest affects climate change, and vice versa, how climate change affects the health of the Amazon rainforest. ATTO’s altitude allows scientists to make atmospheric measurements over such a large area that they can accurately predict the impact of various factors – including human activity – on the climate. In Manaus, the ATTO data are sent to the National Institute for Amazonian Research (INPA), and in Germany they are analyzed by the Max Planck Institute for Biogeochemistry in Jena and the Max Planck Institute for Chemistry in Mainz.

Will the Amazon become a CO₂ supplier?

The environmental situation in much of the Amazon is downright alarming. Some forest and climate scientists say tipping points are imminent, others say they are already here. Are they right? Are there already areas in the Amazon where the destruction is irreversible, with far-reaching consequences for the forest, its biodiversity, the people who live there, and not least for the climate?

Several experts in climate and forest research with whom I have spoken over the years are adamant: The threshold has been crossed. There are tipping points in the Amazon.

“If nothing changes in the next four to eight years, the destruction of the Amazon rainforest will be irreversible. So said Brazilian scientist Paulo Artaxo, professor of atmospheric physics at the University of São Paulo, in an interview with BBC News Brazil in the summer of 2019. According to another Brazilian scientist, Antônio Nobre, associated with the Brazilian National Institute of Space Research INPE, who made global headlines a few years ago with his report on “Flying Rivers,” some parts of the Amazon have already passed a tipping point. He told me in 2017 that parts of the remaining forests in the eastern Amazon were burning more frequently than ever before, pointing to what he called “the perverse, self-reinforcing cycle of climate-driven destruction.” Niro Higuchi, a forest scientist at the National Institute for Amazonian Research (INPA) in Manaus, is also convinced that tipping points have already been reached in parts of the Amazon. He mentioned the south of the Brazilian Amazon, specifically the north of the state of Mato Grosso and the south of the state of Pará.In the Netherlands, Hans Ter Steege, group leader for Biodiversity Dynamics at the national research institute Naturalis in Leiden and professor of Tropical Forest Diversity and Tree Traits at the Free University of Amsterdam, is less sure. Is there really a tipping point? Hans Ter Steege has his doubts, as he said in the fall of 2019. “There are people who say that there are two stable situations for the area, it is either forest or savanna, and once it has become savanna, it does not gradually return to forest, it has to go all the way back to the starting point. I don’t know, because that would mean that after the Ice Age, when it got warmer, it happened with a shock. We also don’t know exactly how much was cut down in the area before the indigenous population completely collapsed. It was a lot. What was left in those places was savanna and patches of forest. Yet that forest has come back.”Are there already tipping points in the Amazon?

Santiago Botia is a Ph.D. student at the Max Planck Institute for Biochemistry in Jena, Germany. He specializes in greenhouse gases in general and those measured at and on ATTO in particular.

When I ask him in 2021, Santiago Botia finds the question as difficult as Hans Ter Steege did earlier. “There are indeed people who say that. There is already a change in forest land use of about 17 percent, and another 17 percent is affected. So we are moving towards 40 percent deforested or degraded forest. Research suggests that at more than 20 to 30 percent deforestation, there is a tipping point, and tipping points are by definition irreversible states. The forest goes into a different state. I don’t think we’re there yet. But it could happen. The point is that we don’t know how close we are to a tipping point, but we do know where in the forest, or where in the regional delineation of the Amazon, we are closer to a tipping point.”

He continues: “When we talk about greenhouse gases, there are two that are very important, carbon dioxide and methane. These two gases make up less than 1 percent of the atmospheric composition, but they have a significant impact on the atmosphere and climate. The key process that controls carbon dioxide is photosynthesis. Vegetation absorbs carbon released by natural and human-caused fires, fossil fuel combustion, microbial decomposition of organic matter, and plant metabolism, also known as plant respiration. For methane, there are natural emissions from wetlands, fossil fuels, and fires. And much of it comes from agriculture and waste. These are the main processes that determine the levels of these two gases in the atmosphere.”

Over the past eight hundred thousand years, the concentrations of these gases in the atmosphere have fluctuated from high to low over a period of several thousand years. But now, in a very short period of time, the concentrations of these gases have increased significantly. This is clear evidence that humans and human activities are having a significant impact on the concentrations of CO₂ and methane. These two gases are largely responsible for the current warming of the Earth.

Santiago Botia: “The role of the Amazon in terms of greenhouse gases can be summarized in a few key aspects. In terms of carbon, the Amazon is a huge reservoir of carbon, in the forest and in the soil. The scale of this is enormous. However, there is widespread recent evidence that the vegetation sink is shrinking. Carbon is still being absorbed. But the ability of vegetation to absorb CO₂ from the atmosphere appears to be declining. There is now an increasing threat of deforestation, degradation, agricultural expansion, and also climate variability, which means that all the carbon stored in the forest could be released into the atmosphere.”.

Parts of the Amazon would no longer absorb carbon dioxide, but become suppliers of CO₂. If this is true, what are the consequences for the climate and climate change?

Santiago Botia: “As I said, carbon dioxide is closely linked to vegetation. Previous findings, recently confirmed, have shown that good vegetation management is crucial in this regard and is often associated with life in indigenous areas and national parks. Up to 58 percent of above-ground carbon is stored in these areas. These places are therefore essential for keeping carbon in the forest, preventing deforestation and storing large amounts of carbon. But the Amazon’s carbon balance also has a human component.”If you look at the vegetation in general, all the trees that make up the Amazon rainforest, if you look at it holistically, the vegetation is still a carbon sink. But that picture can change if you look at different places regionally, for example in the southeast. There was a paper in 2015 that took measurements in ecological plots over thirty years, and the researchers saw that the size of the sink was decreasing. When there are studies that say the Amazon is a source of carbon, they look at the vegetation and at the same time they look at fires and deforestation. If you add up what the vegetation absorbs and subtract what is released by deforestation, then yes, there is a source. Because the carbon sink of vegetation is sometimes very close to zero, almost neutral. It is not that vegetation stops absorbing carbon.

“In the last decade, aircraft measurements have shown that the Amazon can be a source of carbon if you take into account what the vegetation absorbs from the atmosphere and what is released by fires. This happens in places where the number of fires is too high. This is a pretty remarkable finding. In the eastern Amazon, near Santarém and Belém, there is now a positive flux into the atmosphere. Further west, in Tabatinga, Rio Branco, Tefé, the net flux is very low, so there may be a tipping point there as well. Another finding from this research shows what is happening in Alta Floresta, in the southeast of the Amazon, the Arc of Deforestation (deforestation in the Amazon rainforest is occurring most rapidly along a curve that spans the southeastern edge of the forest, which scientists have come to call the “Arc of Deforestation” – CCE). It appears that the vegetation there is already losing its ability to absorb carbon from the atmosphere. And that means there is a positive flux there. The researchers of this study suggest that this is related to a high temperature increase due to global warming in this region, deforestation, and also precipitation anomalies or drought in this region.”

What does that mean in terms of climate change?

Santiago Botia: “The Amazon is one of the largest carbon reservoirs in the world. So if this deforestation trend continues, and it seems to be happening in Brazil, but also in Colombia and elsewhere, a huge amount of carbon will be released into the atmosphere, and the global land sink will be much smaller. And that is clearly not good for the climate.”

So much for the Amazon and carbon dioxide and methane. For my questions on biodiversity, I will be consulting, among others, the Brazilian Eliane Gomes Alves, who, after her training at INPA in Manaus, is now a postdoctoral researcher in the ATTO team at the Max Planck Institute for Biochemistry in Jena.

To be continued…

Total: € -

Former music journalist. Swapped the editorship of the Dutch music magazine OOR for a hammock in the Amazon in the 1990s.