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Water recycled through transpiring forests influences the spatial distribution of precipitation in the Amazon and has been shown to play a role in the initiation of the wet season. However, due to the challenges and costs associated with measuring evapotranspiration (ET) directly and high uncertainty in remote-sensing ET retrievals, the spatial and temporal patterns in Amazon ET remain poorly understood. In this study, we estimated ET over the Amazon and 10 sub-basins using a catchment-balance approach, whereby ET is calculated directly as the balance between precipitation, runoff, and change in groundwater storage. We compared our results with ET from remote-sensing datasets, reanalysis, models from Phase 5 and Phase 6 of the Coupled Model Intercomparison Projects (CMIP5 and CMIP6 respectively), and in situ flux tower measurements to provide a comprehensive overview of current understanding. Catchment-balance analysis revealed a gradient in ET from east to west/southwest across the Amazon Basin, a strong seasonal cycle in basin-mean ET primarily controlled by net incoming radiation, and no trend in ET over the past 2 decades. This approach has a degree of uncertainty, due to errors in each of the terms of the water budget; therefore, we conducted an error analysis to identify the range of likely values. Satellite datasets, reanalysis, and climate models all tended to overestimate the magnitude of ET relative to catchment-balance estimates, underestimate seasonal and interannual variability, and show conflicting positive and negative trends. Only two out of six satellite and model datasets analysed reproduced spatial and seasonal variation in Amazon ET, and captured the same controls on ET as indicated by catchment-balance analysis. CMIP5 and CMIP6 ET was inconsistent with catchment-balance estimates over all scales analysed. Overall, the discrepancies between data products and models revealed by our analysis demonstrate a need for more ground-based ET measurements in the Amazon as well as a need to substantially improve model representation of this fundamental component of the Amazon hydrological cycle.

The climate in the Amazon region is particularly sensitive to surface processes and properties such as heat fluxes and vegetation coverage. Rainfall is a key expression of the land surface atmosphere interactions in the region due to its strong dependence on forest transpiration. While a large number of past studies have shown the impacts of large-scale deforestation on annual rainfall, studies on the isolated effects of elevated atmospheric CO2concentrations (eCO2) on canopy transpiration and rainfall are scarcer. Here, for the first time, we systematically compare the plant physiological effects of eCO2and deforestation on Amazon rainfall. We use the CPTEC Brazilian Atmospheric Model (BAM) with dynamic vegetation under a 1.5CO2experiment and a 100% substitution of the forest by pasture grasslands, with all other conditions held similar between the two scenarios. We find that both scenarios result in equivalent average annual rainfall reductions (Physiology: 257 mm, 12 %; Deforestation: 183 mm, 9 %) that are above the observed Amazon rainfall interannual variability of 5 %. The rainfall decreases predicted in the two scenarios are linked to a reduction of approximately 20% in canopy transpiration but for different reasons: The eCO2-driven reduction of stomatal conductance drives the change in the Physiology experiment, and the smaller leaf area index of pasturelands (72% compared to tropical forest) causes the result in the Deforestation experiment. The Walker circulation is modified in the two scenarios: in Physiology due to a humidity-enriched free troposphere with decreased deep convection due to the heightening of a drier and warmer (C2.1 C) boundary layer, and in Deforestation due to enhanced convection over the Andes and a subsidence branch over the eastern Amazon without considerable changes in temperature (0.2 C in 2m air temperature and C0.4 C in surface temperature). But again, these changes occur through different mechanisms: strengthened west winds from the Pacific and reduced easterlies entering the basin affect the Physiology experiment, and strongly increased easterlies influence the result of the Deforestation experiment. Although our results for the Deforestation scenario agree with the results of previous observational and modelling studies, the lack of direct field-based ecosystem-level experimental evidence regarding the effect of eCO2on moisture fluxes in tropical forests confers a considerable level of uncertainty to any projections of the physiological effect of eCO2on Amazon rainfall. Furthermore, our results highlight the responsibilities of both Amazonian and non-Amazonian countries to mitigate potential future climatic change and its impacts in the region, driven either by local deforestation or global CO2emissions.

This study investigates the main threats related to environmental degradation that affect Amazonian Indigenous Lands (ILs). Through a cluster analysis, we group ILs according to the set of common environmental threats that occur within and outside their limits. The results show that most of the 383 ILs are affected internally by a combination of different environmental threats, namely: deforestation, forest degradation, fires, mining, croplands, pastures, and roads. However, the ILs affected by multiple and relatively severe threats are mainly located in the arc of deforestation and the Roraima state. The threats related to forest loss (deforestation, forest degradation, and fires) are more intense in the ILs buffer zones than within, showing that ILs effectively promote environmental preservation. In the cluster analysis, we identified seven clusters that are characterized by common environmental threats within and around their limits, and, based on these results, we have outlined four environmental policy priorities to be strengthened and applied in Amazonian ILs: protecting ILs buffer zones; strengthening surveillance actions, and combating illegal deforestation, forest degradation, and mining activities in ILs; preventing and fighting fires; and removing invaders from all ILs in the Amazon. In this study, we warn that the threats presented make the Indigenous peoples in the Amazon more vulnerable. To guarantee indigenous peoples rights, illegal actions in these territories and their surroundings must be contained, and quickly.

This study investigates the main threats related to environmental degradation that affect Amazonian Indigenous Lands (ILs). Through a cluster analysis, we group ILs according to the set of common environmental threats that occur within and outside their limits. The results show that most of the 383 ILs are affected internally by a combination of different environmental threats, namely: deforestation, forest degradation, fires, mining, croplands, pastures, and roads. However, the ILs affected by multiple and relatively severe threats are mainly located in the arc of deforestation and the Roraima state. The threats related to forest loss (deforestation, forest degradation, and fires) are more intense in the ILs buffer zones than within, showing that ILs effectively promote environmental preservation. In the cluster analysis, we identified seven clusters that are characterized by common environmental threats within and around their limits, and, based on these results, we have outlined four environmental policy priorities to be strengthened and applied in Amazonian ILs: protecting ILs buffer zones; strengthening surveillance actions, and combating illegal deforestation, forest degradation, and mining activities in ILs; preventing and fighting fires; and removing invaders from all ILs in the Amazon. In this study, we warn that the threats presented make the Indigenous peoples in the Amazon more vulnerable. To guarantee indigenous peoples rights, illegal actions in these territories and their surroundings must be contained, and quickly.

Tropical forests are an important part of global water and energy cycles, but the mechanisms that drive seasonality of their land-atmosphere exchanges have proven challenging to capture in models. Here, we (1) report the seasonality of fluxes of latent heat (LE), sensible heat (H), and outgoing short and longwave radiation at four diverse tropical forest sites across Amazonia-along the equator from the Caxiuana and Tapajos National Forests in the eastern Amazon to a forest near Manaus, and from the equatorial zone to the southern forest in Reserva Jaru; (2) investigate how vegetation and climate influence these fluxes; and (3) evaluate land surface model performance by comparing simulations to observations. We found that previously identified failure of models to capture observed dry-season increases in evapotranspiration (ET) was associated with model overestimations of (1) magnitude and seasonality of Bowen ratios (relative to aseasonal observations in which sensible was only 20%-30% of the latent heat flux) indicating model exaggerated water limitation, (2) canopy emissivity and reflectance (albedo was only 10%-15% of incoming solar radiation, compared to 0.15%-0.22% simulated), and (3) vegetation temperatures (due to underestimation of dry-season ET and associated cooling). These partially compensating model-observation discrepancies (e.g., higher temperatures expected from excess Bowen ratios were partially ameliorated by brighter leaves and more interception/evaporation) significantly biased seasonal model estimates of net radiation (R-n), the key driver of water and energy fluxes (LE similar to 0.6 R-n and H similar to 0.15 R-n), though these biases varied among sites and models. A better representation of energy-related parameters associated with dynamic phenology (e.g., leaf optical properties, canopy interception, and skin temperature) could improve simulations and benchmarking of current vegetation-atmosphere exchange and reduce uncertainty of regional and global biogeochemical models.

Agricultural systems play a key role in achieving many of the Sustainable Development Goals, established by the United Nations, given the current challenge of producing enough food to feed a global population that is expected to reach 10 billion people by 2050. More efficient and sustainable use of nutrients in agriculture is an important step to increasing production while minimizing threats to natural ecosystems and resource depletion. In this study, we developed a system nutrient balance for nitrogen (N) and phosphorus (P) to evaluate nutrient use practices in cropping and grazing systems in the Vermelho River watershed (VRW), Upper Pantanal, Brazil, and investigated options to improve N and P use efficiency (NUE and PUE). Our results show P balance in cropping systems are positive while those in grazing systems tend to be negative. The positive values in cropping systems are due to both high P inputs from mineral fertilizers and high soil P-sorbing capacities. The negative values in grazing systems are a result of the removal of animal products without replacing the nutrients. Most of the N inputs in the crops grown in this region come from biological nitrogen fixation. The NUE in cropping systems is about 0.95, which is higher than the upper critical value of the desirable range (0.60.9). Given the high NUE value and the risk of soil mining, improving cropping systems NUE by adjusting the inputs to replenish N outputs and avoid soil erosion in the VRW are of considerable interest.

One of the most crucial parts of solid waste management is determining landfill site location, since multiple factors must be considered and there is no universal formula. The main purpose of this study is to make a worldwide systematic review of restriction criteria used for landfill siting using geographic information systems (GIS). Literature from the last years was thoroughly assessed, and 45 restrictions found were classified as environmental, economic, or social criteria. Our findings show that although the number of articles published has increased recently, they use on average seven restrictions, focusing mainly on environmental over economic and social criteria. In our boxplot statistical analysis, the most frequently used environmental restrictions are the distance from surface water resources (used in 77% of articles), slope (52%), and distance from groundwater founts (40%), with a median of 300 m, 20%, and 250 m, respectively. The most frequently used economic restrictions are distances from roads (60%), airports (40%), and power lines (18%), with medians of 275 m, 3000 m, and 75 m, respectively. The most frequently used social restrictions are distances from urban areas (45%), settlements and residential areas (40%), and cultural heritage or archaeological areas (23%), with medians of 1000 m. This information might help, on the one hand, governments to develop new legislation about landfill siting and on the other hand, decision-makers and scientists to produce new studies with different restrictive scenarios.

The Amazon Basin is at the center of an intensifying discourse about deforestation, land-use, and global change. To date, climate research in the Basin has overwhelmingly focused on the cycling and storage of carbon (C) and its implications for global climate. Missing, however, is a more comprehensive consideration of other significant biophysical climate feedbacks [i.e., CH4, N2O, black carbon, biogenic volatile organic compounds (BV0Cs), aerosols, evapotranspiration, and albedo] and their dynamic responses to both localized (fire, land-use change, infrastructure development, and storms) and global (warming, drying, and some related to El Nino or to warming in the tropical Atlantic) changes. Here, we synthesize the current understanding of (1) sources and fluxes of all major forcing agents, (2) the demonstrated or expected impact of global and local changes on each agent, and (3) the nature, extent, and drivers of anthropogenic change in the Basin. We highlight the large uncertainty in flux magnitude and responses, and their corresponding direct and indirect effects on the regional and global climate system. Despite uncertainty in their responses to change, we conclude that current warming from non-CO2 agents (especially CH4 and N2O) in the Amazon Basin largely offsets- and most likely exceeds-the climate service provided by atmospheric CO2 uptake. We also find that the majority of anthropogenic impacts act to increase the radiative forcing potential of the Basin. Given the large contribution of less-recognized agents (e.g., Amazonian trees alone emit similar to 3.5% of all global CH4), a continuing focus on a single metric (i.e., C uptake and storage) is incompatible with genuine efforts to understand and manage the biogeochemistry of climate in a rapidly changing Amazon Basin.

The Paraguaçu River is one of the most important rivers in Bahia State, Brazil, and the main tributary of the Todos os Santos Bay, the second largest in that country. We evaluated the spatio-temporal variations in the composition and structure of the phytoplankton community in the Paraguaçu River estuary as influenced by rainfall and fluvial discharge from the Pedra do Cavalo dam. Bi-monthly collections were carried out from May 2018 to March 2019 at 12 sampling stations in the estuary. During this period, phytoplankton samples, water samples to determinate the concentration of dissolved inorganic nutrients and data on salinity, temperature, pH, dissolved oxygen, and water transparency were collected. Data on rainfall and dam discharge were also obtained. Abiotic variables and chlorophyll-a showed significant differences in the estuary zones, and silicate concentrations demonstrated differences between the dam discharge periods. A total of 194 phytoplankton taxa were identified, with diatoms showing the highest densities and diversities throughout the study period. Cyclotella meneghiniana, Nitzschia sp., and Scrippsiella acuminata formed blooms in the dry season, whereas blooms of Planktothrix isothrix occurred in the rainy season and during a period of medium dam discharge in the dry season. The influence of dam discharge was quite evident, with increases in nutrient concentrations in the estuary during the months of higher flow that altered the composition and density of the phytoplankton communities in the different system zones. The formation of blooms in response to increased nutrient availability represents an increase in the primary productivity of the system, although blooms of potentially harmful species (such as Planktothrix isothrix) may represent a risk to human activities in the region.

The aim of this work is to present preliminary results of the statistical and dynamical simulations carried out within the framework of the Flagship Pilot Study in southeastern South America (FPS-SESA) endorsed by the Coordinated Regional Climate Downscaling Experiments (CORDEX) program. The FPS-SESA initiative seeks to promote inter-institutional collaboration and further networking with focus on extreme rainfall events. The main scientific aim is to study multi-scale processes and interactions most conducive to extreme precipitation events through both statistical and dynamical downscaling techniques, including convection-permitting simulations. To this end, a targeted experiment was designed considering the season October 2009 to March 2010, a period with a record number of extreme precipitation events within SESA. Also, three individual extreme events within that season were chosen as case studies for analyzing specific regional processes and sensitivity to resolutions. Four dynamical and four statistical downscaling models (RCM and ESD respectively) from different institutions contributed to the experiment. In this work, an analysis of the capability of the set of the FPS-SESA downscaling methods in simulating daily precipitation during the selected warm season is presented together with an integrated assessment of multiple sources of observations and available CORDEX Regional Climate Model simulations. Comparisons among all simulations reveal that there is no single model that performs best in all aspects evaluated. The ability in reproducing the different features of daily precipitation depends on the model. However, the evaluation of the sequence of precipitation events, their intensity and timing suggests that FPS-SESA simulations based on both RCM and ESD yield promising results. Most models capture the extreme events selected, although with a considerable spread in accumulated values and the location of heavy precipitation.

Green-blue infrastructure in urban regions guarantees the provision of resources such as water, energy, and food, which are interdependent and fundamental in ensuring human development. In this study, we analyzed the environmental injustice issue relationships of the supply and production of water, energy, and food in the Sao Paulo Macrometropolis, Brazil. Its 180 municipalities were compared and categorized ~ into losers and winners based on the urban nexus approach, the proportion of green infrastructure, and human development. We applied a neural network self-organizing map to official publicly available data to obtain clusters of municipalities featuring combinations of 19 indicators. The results showed four clusters with three containing characteristics of receivers (Capital, Hinterland, and Developed Receivers) and one of providers, the latter aggregating municipalities with a strong role in providing water, food, and subsidies for energy generation. However, the providers also included the municipalities that had the greatest inequities in terms of human development and social inclusion. The importance of evaluating the co-benefits of green-blue infrastructure in urban spaces can serve as an adaptation strategy to both improve natural resource management and offer support to different processes and ecosystem functions. Our study provides a comprehensive understanding of complex urban systems by considering environmental justice and nexus synergies.

While wind power is a low-carbon renewable energy technology with relatively little land footprint, the necessary infrastructure expansion still has land-related environmental impacts. Brazil has seen more than a ten-fold increase in wind power capacity in the last decade. However, little is known about these impacts of wind power generation in Brazil compared to other world regions, although Brazilian wind power infrastructure is concentrated in the least protected ecosystems that are prone to degradation, desertification and species extinction. This study focuses on land-use impacts of past wind power generation development in four Brazilian federal states, covering 80% of the country’s installed capacity. We assessed their spatial installation patterns, associated land-use and land cover change in the period before installation until 2018, and potential alternative installation locations, using a detailed wind turbine location database in combination with a high-resolution land-use and land cover map. In contrast to wind parks built in Europe, we found that 62% of the studied wind park area was covered by native vegetation and coastal sands. Overall, 3.2% of the total wind cluster area was converted from native vegetation to anthropogenic use. Wind parks installed mainly on native vegetation, on average, underwent higher land-use change compared to other wind parks. As Brazil intends to more than double its current wind power capacities by 2029, we explored possibilities to reduce environmental risks due to wind power expansion. We showed that this is feasible by integrating wind parks into human-altered areas, as sufficient wind resources there are available.