Justification: Changes in global temperature are already affecting many ecosystems. Several studies have already evaluated climate trends in different regions of the world. Regionally, studying Amazon is fundamental due to its important role in regulating regional and global climate. Depicting the recent trends in climate variables, such as temperature, can help understand the magnitude of the observed changes in the Amazon to address and infer how they can affect the socio-environmental systems.

Objective: To quantify the spatial and temporal variability of annual trends in temperature during the dry season from 2003 to 2020 in the Amazon basin.

Methods: We used the dry season onset and duration to calculate spatially explicit mean temperature during this period for each year. Temperature data was acquired from the MODIS/NASA MOD11A2 product, aggregated into 5km² grid pixels. We first calculated the mean temperature per year for the entire study area to evaluate the general trend. Secondly, we performed a grid cell linear regression to obtain the trend analysis (p Results: We observed a positive trend towards increasing the average temperature during the dry season in the Amazon Basin from 2003 to 2020 (p Figure 1). Spatially, most of the southern Amazon, known as the Brazilian arc of deforestation and epicenter of commodities production, is exposed to increased temperatures (Figure 2). Central Amazon, home of pristine forest and many traditional populations, is the second region with the highest positive trend. On the other hand, regions with a negative trend represent only 2% of the basin area (Table 1).

Implications: As a global effort, national targets set in the context of COP26 are not enough to limit global warming to the 1.5°C level. Regionally, it is already possible to observe temperature increases exceeding the global mid-century goal. Furthermore, reducing rainfall accompanied by temperature increases could lead the ecosystems to a continually changing fire-prone environment during the dry season. Our results highlight the importance of short-term actions and policies to adapt and mitigate the impacts that climate change is already imposing on Amazonian ecosystems.