CO₂ emissions in the Amazon: are bottom-up estimates from land use and cover datasets consistent with top-down estimates based on atmospheric measurements?

Autor(es):Mostrar menos -

Tejada, Graciela ; Gatti, Luciana V. ; Basso, Luana S. ; Cassol, Henrique L. G. ; Silva-Junior, Celso H. L. ; Mataveli, Guilherme ; Marani, Luciano ; Arai, Egidio ; Gloor, Manuel ; Miller, John B. ; Cunha, Camilla L. ; Domingues, Lucas G. ; Ipia, Alber ; Correia, Caio S. C. ; Crispim, Stephane P. ; Neves, Raiane A. L. ; Von Randow, Celso

• Tipo de documento: Artigo Científico
• Fonte: FRONTIERS IN FORESTS AND GLOBAL CHANGE; v. 6, p. 15-pg., 2023-08-23.

Resumo

Amazon forests are the largest forests in the tropics and play a fundamental role for regional and global ecosystem service provision. However, they are under threat primarily from deforestation. Amazonia's carbon balance trend reflects the condition of its forests. There are different approaches to estimate large-scale carbon balances, including top-down (e.g., CO2 atmospheric measurements combined with atmospheric transport information) and bottom-up (e.g., land use and cover change (LUCC) data based on remote sensing methods). It is important to understand their similarities and differences. Here we provide bottom-up LUCC estimates and determine to what extent they are consistent with recent top-down flux estimates during 2010 to 2018 for the Brazilian Amazon. We combine LUCC datasets resulting in annual LUCC maps from 2010 to 2018 with emissions and removals for each LUCC, and compare the resulting CO2 estimates with top-down estimates based on atmospheric measurements. We take into account forest carbon stock maps for estimating loss processes, and carbon uptake of regenerating and mature forests. In the bottom-up approach total CO2 emissions (2010 to 2018), deforestation and degradation are the largest contributing processes accounting for 58% (4.3 PgCO(2)) and 37% (2.7 PgCO(2)) respectively. Looking at the total carbon uptake, primary forests play a dominant role accounting for 79% (-5.9 PgCO(2)) and secondary forest growth for 17% (-1.2 PgCO(2)). Overall, according to our bottom-up estimates the Brazilian Amazon is a carbon sink until 2014 and a source from 2015 to 2018. In contrast according to the top-down approach the Brazilian Amazon is a source during the entire period. Both approaches estimate largest emissions in 2016. During the period where flux signs are the same (2015-2018) top-down estimates are approximately 3 times larger in 2015-2016 than bottom-up estimates while in 2017-2018 there is closer agreement. There is some agreement between the approaches-notably that the Brazilian Amazon has been a source during 2015-2018 however there are also disagreements. Generally, emissions estimated by the bottom-up approach tend to be lower. Understanding the differences will help improve both approaches and our understanding of the Amazon carbon cycle under human pressure and climate change. (AU)

• Processo FAPESP: 18/14006-4 - Estimativa dos Balanços de Gases de Efeito estufa da Amazonia utilizando Modelo Inverso de Transporte Atmosférico
• Beneficiário: Luana Santamaria Basso
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 18/18493-7 - Correlação entre gases de efeito estufa, processos naturais e uso da terra na região da Bacia Amazônica
• Beneficiário: Graciela Tejada Pinell
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 16/02018-2 - Variação interanual do balanço de gases de efeito estufa na Bacia Amazônica e seus controles em um mundo sob aquecimento e mudanças climáticas – Carbam: estudo de longo termo do balanço do carbono da Amazônia
• Beneficiário: Luciana Vanni Gatti
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático
• Processo FAPESP: 19/25701-8 - Influência do uso e cobertura da terra na emissão de material particulado fino (PM2,5µm) por queimadas nos biomas Amazônia e Cerrado integrando modelagem e sensoriamento remoto
• Beneficiário: Guilherme Augusto Verola Mataveli
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado