Sugarcane has contributed to removing carbon from the atmosphere over the last 20 years in Brazil

A study carried out by Agroicone, Unicamp and Embrapa Meio Ambiente indicates that the dynamics of land occupation due to the cultivation of sugar cane over the last 20 years in Brazil, contrary to expectations, was responsible for the removal of carbon from the atmosphere , with an increase over natural vegetation of only 1,6%. The results of the assessment have important repercussions on demanding national and international bioenergy markets and certifications, as well as regulations, in which the impacts of land use are always points of attention.

In the assessment of the professor at the Faculty of Mechanical Engineering at Unicamp, Joaquim Seabra, one of the authors of the study, the work highlighted the relevance of having a more refined parameterization to estimate the behavior of carbon stocks in Brazil in the sugarcane sector -sugar.

“It has become very clear that the use of more precise parameters for carbon stock can significantly alter the conclusions about land use change, which have been disseminated by different international schemes, whether certification or regulatory schemes. Considering production conditions in the national context, we have strong evidence that we can have more carbon removals and at the same time limit the risk of indirect effects (i.e., expansion of areas over natural vegetation) here in Brazil,” he says.

The research evaluated the dynamics of land occupation by sugarcane cultivation in the Center-South and North of Brazil, between the years 2000 and 2020. The result of this investigation showed that 25% of the currently existing sugarcane area was already sugarcane in 2000. The increase of 6,1 million hectares of sugarcane, identified in this period, came from conversions of areas that were previously pastures (60%), annual crops (16%) and mosaics (22%) – or that is, areas that could combine agriculture and pasture. Only 1,6% of sugarcane expansion occurred in areas of natural vegetation.

This pattern of land use conversion, associated with the exchange of technology from burnt sugarcane (fire during the harvest) to raw sugarcane (with the maintenance of straw in the field), contributed to the areas cultivated with sugarcane being responsible for the net removal of approximately 9,8 million tons of CO2 per year from the atmosphere. When considering the agricultural property as a whole, and not just the area cultivated with sugar cane, the net removal was 17 million tons of CO2 per year, mainly due to the maintenance of natural vegetation and the increase in natural forest formations in these properties.

Considering only sugarcane cultivated areas, the amount of carbon removed (9,8 MtCO2/year) accumulated over the 20 years evaluated represents a total removal of 196 MtCO2, which would be equivalent to planting 1,4 billion trees, occupying an area more than 1 million football pitches or 80 times the city of Paris covered in forest.

In Brazil, the production of bioenergy from sugar cane is fundamental for the decarbonization of the energy and transport matrix. As a result, it is an important ally in fulfilling the commitments established to reduce CO2 emissions in its NDC (Nationally Determined Contribution to the Paris Agreement). The change in land use associated with sugarcane cultivation is a critical process for its sustainability and the estimates made so far indicated, predominantly, greenhouse gas emissions associated with sugarcane production. As Embrapa Meio Ambiente researcher Nilza Ramos highlights, “based on a broad set of data and a series of methodological refinements, the study demonstrated a relevant contribution of sugarcane cultivation to carbon removals associated with the use of land in Brazil”.

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The researchers quantified the effect of sugarcane cultivation and expansion and changing crop management on soil carbon stocks and biomass over the last two decades. The analysis was carried out considering sugarcane cultivation areas and rural properties (Rural Environmental Registry - CAR) with raw material production. In total, 90,7% of the sugarcane cultivated area in Brazil was analyzed, which corresponds to 93% of national sugar and ethanol production. Rural properties with sugarcane cultivation in the North of the country were also analyzed, which despite accounting for only 0,5% of national production, are the constant object of international attention.

The study was published in the international scientific journal Land and was based on publicly available and internationally recognized databases. Data on conversion of sugarcane areas and pasture quality were obtained from the MapBiomas platform, data on rural properties (CAR) from Imaflora and the Brazilian Forest Service and carbon stock data from new estimates made by the team and from the BRLUC method from Embrapa. “We tried to use methodologies and data sources that were supported by the international scientific community”, says Nilza Ramos.

“The results confirm a growing concept that we can store carbon in energy systems, notably when bioenergy is applied correctly. In this specific case, given the period under analysis, the results reflect the sugarcane market behavior, guided by the Forest Code and commitments of the sugar-energy sector. The expectation is that RenovaBio's eligibility criteria can further reinforce these positive impacts, but this can only be verified over the years of this policy by carrying out new studies”, according to the study leader, partner and researcher at Agroicone, Marcelo Moreira.

Additionally, Seabra believes that the results of the article may have wider repercussions. “The results may be important both for the general assessment of the sustainability of production systems based on sugarcane production, and they may also provide more appropriate parameters for analyzes within these regulatory or policy contexts, or international certification schemes. focused on biofuels”, he believes.

Funding for this research came from the IEA (International Energy Agency) and Raízen for Agroicone and Unicamp, and from the Ministry of Mines and Energy and Finep for Embrapa.

The article is available at this link.