Spatial–temporal dynamics of aboveground biomass (AGB) and forest area affect the carbon cycle, climate and biodiversity in the Brazilian Amazon. Here we investigate interannual changes in AGB and forest area by analysing satellite-based annual AGB and forest area datasets. We found that the gross forest area loss was larger in 2019 than in 2015, possibly due to recent loosening of forest protection policies. However, the net AGB loss was three times smaller in 2019 than in 2015. During 2010–2019, the Brazilian Amazon had a cumulative gross loss of 4.45 Pg C against a gross gain of 3.78 Pg C, resulting in a net AGB loss of 0.67 Pg C. Forest degradation (73%) contributed three times more to the gross AGB loss than deforestation (27%), given that the areal extent of degradation exceeds that of deforestation. This indicates that forest degradation has become the largest process driving carbon loss and should become a higher policy priority.

地上生物量 (AGB) 和森林面积的时空动态影响巴西亚马逊地区的碳循环、气候和生物多样性。在这里，我们通过分析基于卫星的年度 AGB 和森林面积数据集来研究 AGB 和森林面积的年际变化。我们发现，2019 年森林总面积损失大于 2015 年，可能是由于近期森林保护政策松动所致。然而，2019 年的净 AGB 损失是 2015 年的三倍。在 2010-2019 年期间，巴西亚马逊的累计毛损失为 4.45 Pg C，而总收益为 3.78 Pg C，导致 AGB 净损失为 0.67 Pg C. 考虑到面积退化程度超过森林砍伐，森林退化（73%）对 AGB 总损失的贡献是森林砍伐（27%）的三倍。