Record decline and slowing down of canopy-greenness in Amazonia during the 2023/2024 drought

In 2023/2024 Amazonia was struck by a record drought[1]. To date, only few studies have quantified the impact of this event on the Amazon rainforest. While these studies provide first insights on the response of Amazonia to the record drought, they did not include the second peak of drought in September 2024 or assess recovery trajectories succeeding this event.

To fill this gap, we here present analyses based on observations spanning 23 years of canopy-greenness. In particular, we compare the impact of the 2023/2024 drought with previous major droughts and quantify long-term trends of the enhanced vegetation index (EVI), extending the period under investigation from previous studies by more than a year. Moreover, we evaluate indicators of slowing down and reduced forest resilience, i.e. temporal autocorrelation and variance[2]. Finally, we assess how shallow water-table depth have buffered canopy-greenness decline as done in previous studies[3,4].

We observed record low EVI and declining forest resilience as indicated by a rising temporal autocorrelation and variance which remained on record levels even after the drought relaxation early in 2025. Specifically, the area featuring more than 10 % EVI decline reached a record spatial extent of 14 % early in 2025, while the spatial shares of regions featuring high temporal autocorrelation and variance were 2 and 3.4 times higher than under average conditions. Moreover, we observed shallow water tables to significantly buffer the negative drought impact on canopy greenness. Interestingly, shallow water tables appeared to be more prone to a slowing down which remains subject to further investigation. Taken together, our results point at an unprecedented decline and slowing down of canopy greenness dynamics in Amazonia up until September 2025, indicating the necessity to more closely assess direct and ongoing impacts of this event by means of ground observations, remotely-sensed indicators of productivity (e.g. SIF, VOD), and simulations from dynamic vegetation models.

 

[1]        Ferreira V, Buras A, Zscheischler J, Mahecha M and Rammig A 2025 Evaluating the 2023–2024 record dry-hot conditions in the Amazon in the context of historical compound extremes Environ. Res. Lett. 20 084055

[2]        Scheffer M, Bascompte J, Brock W A, Brovkin V, Carpenter S R, Dakos V, Held H, van Nes E H, Rietkerk M and Sugihara G 2009 Early-warning signals for critical transitions Nature 461 53–9

[3]        Costa F R C, Schietti J, Stark S C and Smith M N 2023 The other side of tropical forest drought: do shallow water table regions of Amazonia act as large-scale hydrological refugia from drought? New Phytologist 237 714–33

[4]        Chen S, Stark S C, Nobre A D, Cuartas L A, de Jesus Amore D, Restrepo-Coupe N, Smith M N, Chitra-Tarak R, Ko H, Nelson B W and Saleska S R 2024 Amazon forest biogeography predicts resilience and vulnerability to drought Nature 631 111–7