Megaproject in the Amazon will test carbon absorption – 09/04/2023 – Environment

In times of climate crisis, it is easy to come across expressions such as “CO capture potential_two of the Amazon” and carbon credits. But do we really know how much carbon the forest can absorb? The answer is still not precise, despite the obvious importance of conservation of the biome.

Several studies have been trying to improve how we measure the carbon emitted or captured by the Amazon. With outdated data, the risk is that we overestimate the potential of the forest in a world that urgently needs to reduce CO emissions_two.

One of the most ambitious projects in progress, Amazon Face (abbreviation of the expression in English “Free-air CO_two enrichment”, or enrichment by CO_two free), should come into action in 2024.

The idea of ​​the project is to verify how the forest behaves under higher concentrations of CO_two up in the air. To do so, the researchers installed towers forming huge circles —with 30 meters in diameter and structures 35 meters high— in forest areas in the Amazon where they will pump carbon dioxide.

The structures of part of the towers, which reach the treetops, have already been erected in the forest, but the heavier research work will only begin at the end of next year. Basically, two of the six rings are complete – which puts the project currently in its phase 2, which consists of the pilot of the large-scale and long-term experiment.

The cost of the project, for ten years of experiment, is estimated at US$ 78.5 million (R$ 387 million, at the current exchange rate), made possible by the MCTI (Ministry of Science, Technology and Innovation). The British government, which has cooperation with Brazil in the project, has released around 7.3 million pounds (more than R$ 45 million) for Amazon Face since 2021.

Amazon Face, explains David Lapola, one of the project coordinators and a researcher at Unicamp, wants to anticipate the future of the forest, predicting a situation in which we will have more CO_two In the atmosphere.

According to Lapola, the available models, in general, show a significant increase in biomass and forest productivity with this “fertilization” by CO_two. The problem: these studies were carried out in temperate forests, not in realities such as the Amazon.

Such growth in temperate forests, however, has not been continuous. Lapola says that, after just over half a decade, the increase in productivity stopped due to the lack of nutrients in the soil.

In the case of the Amazon, the question begins differently. According to the Amazon Face coordinator, the project was installed in a region representing around 60% of the Amazon basin, a soil poor in phosphorus, which is the essential “brick” for building the plants.

“The plant can even produce a simple sugar [com aumento da disponibilidade de CO₂], but cannot allocate this to biomass, especially in the trunk. Any part where it needs to grow, it’s going to need phosphorus,” says Lapola.

Better understanding such processes in a forest the size of the Amazon is essential when we talk about the climate future. “It is one of the most glaring uncertainties of climate systems”, summarizes Lapola. “What we are going to do is make the projections and models more reliable.”

Having more information about the forest’s capacity to absorb carbon is also essential to pinpoint the so-called point of no return —a situation in which the biome, due to deforestation and climate change, would enter a savannization process, ceasing to be a humid forest.

Lapola points out that most of the climate models that make up the IPCC (UN Intergovernmental Panel on Climate Change) still look at tropical forests as places with CO absorption_two permanent. Therefore, the figures for how much tropical forests are really helping the climate “are very likely overestimated”, says the researcher.

“Amazon Face will show that this value may be less than that, but that it is dynamic. This changes our emissions report for the climate convention [da ONU]”, says the scientist.

The need to improve carbon measurements in the Amazon also guides the work of Luciana Gatti, a researcher at INPE (National Institute for Space Research). She is one of the authors of a recent article that shows how different methods produce very different calculations of Amazonian emissions.

The study found, for example, that the estimates known as “top-down” (from top to bottom), made periodically in the Amazon by researchers from Inpe with aircraft overflying to verify the atmospheric concentrations of CO_two, show more emissions than the “bottom-up” methodology, which is based on estimates. The article points out that the “bottom-up” modeling, which is widely used, may be underestimating emissions.

“The ideal is to integrate the two and improve the processes of understanding”, says Gatti.

“The Amazon is changing, it is being affected by deforestation, which is putting a stressful climate condition. If it is changing and we use the same rates [para comparação e cálculo de emissões] for 20 years, we have been treating these processes inappropriately”, he says.