The Caatinga biome was responsible for 38% of greenhouse gas removals in Brazil in 2022, according to a survey carried out by the Caatinga and Desertification Observatory (OCA), at the Federal University of Campina Grande (UFCG). The number was based on the Climate TRACE inventory, which tracks international data on gas emission and removal and other environmental variables.
According to the inventory, in 2022 the Caatinga corresponded to the removal of 410 million tons of CO₂ from the atmosphere. The biome surpassed the Atlantic Forest and the Cerrado, responsible for the withdrawal of 320 and 240 million tons of gas, respectively.
According to OCA researchers, the data shows the Caatinga's potential to participate in the carbon market, which will be regulated in Brazil from 2024.
The characteristics of the Caatinga contribute to the process of removing carbon dioxide, according to the researchers. Naturally, during the photosynthesis process, the biome transforms around 60% of the absorbed gas into biomass, reincorporating the residue into leaves, branches, trunks and roots.
"In the Amazon, this percentage is around 30%, because the ecosystem's respiration causes a greater portion of the absorbed carbon to return to the atmosphere", explained the researchers.
Another process characteristic of the biome that increases the efficiency of gas absorption occurs during periods of rain.
"After months of drought, a few days of rain can reactivate photosynthesis and cause the biome to become an intense CO₂ sink, that is, it begins to remove more CO₂ from the atmosphere than it releases. Science already recognizes that the world's semi-arid ecosystems are responsible for a large part of the annual variation in the global carbon cycle, that is, they influence how much carbon is absorbed and released by terrestrial vegetation from one year to the next", they said.
Despite the potential for the carbon market, Caatinga still has few projects aimed at generating credits in the region. According to OCA researchers, this is because most of the methodologies used to measure credits were developed for humid environments and do not adapt to the conditions of the biome.
OCA researchers hope that new technologies will make it possible to better measure the potential of the Caatinga and increase the biome's participation in the carbon market.
"For the Caatinga, what is missing is not specific regulation, but recognized measurement methodologies that reflect the dynamics of the biome, and mechanisms for communities and small producers to access certification. This is what the OCA has been working on, including contributions to the public consultation", they explained.
The carbon market is a system that regulates and encourages the reduction or removal of carbon dioxide from the atmosphere. The system works by generating “points”, called carbon credits.
Credits are generated by projects that reduce or remove greenhouse gases from the atmosphere. According to OCA researchers, some of these initiatives are: protecting forests against deforestation; recovery of degraded areas; carbon storage in the soil through agricultural practices; renewable energy generation; waste treatment; increased efficiency in industrial processes.
For credits to be considered valid, projects undergo analysis and certification. Once certified, they can be sold, moving the market.
"For these actions to generate credits, their results must be measured and proven, following defined rules and criteria. Once these results have been proven and certified, the credits can be generated and sold. The resources obtained from the sale can finance the project's actions and benefit the actors involved in its implementation, while those who purchase the credits can use them to offset part of their own emissions."
In addition to private companies, the State itself can buy and sell carbon credits. The revenue obtained can be used, for example, in investments in public services.
"Revenue can indeed reinforce the budget (...) it depends on price, demand and certification rules, which fluctuate, and therefore should not be treated as a stable source for continued policies. It serves as a complement", they concluded.
