Amazon hydrology from space : scientific advances and future challenges

As the largest river basin on Earth, the Amazon is of major importance to the world's climate and water resources. Over the past decades, advances in satellite-based remote sensing (RS) have brought our understanding of its terrestrial water cycle and the associated hydrological processes to a new era. Here, we review major studies and the various techniques using satellite RS in the Amazon. We show how RS played a major role in supporting new research and key findings regarding the Amazon water cycle, and how the region became a laboratory for groundbreaking investigations of new satellite retrievals and analyses. At the basin-scale, the understanding of several hydrological processes was only possible with the advent of RS observations, such as the characterization of "rainfall hotspots" in the Andes-Amazon transition, evapotranspiration rates, and variations of surface waters and groundwater storage. These results strongly contribute to the recent advances of hydrological models and to our new understanding of the Amazon water budget and aquatic environments. In the context of upcoming hydrology-oriented satellite missions, which will offer the opportunity for new synergies and new observations with finer space-time resolution, this review aims to guide future research agenda toward integrated monitoring and understanding of the Amazon water from space. Integrated multidisciplinary studies, fostered by international collaborations, set up future directions to tackle the great challenges the Amazon is currently facing, from climate change to increased anthropogenic pressure

Expansão da soja no Brasil: uma avaliação quantitativa de mudanças tecnológicas e ambientais passadas e implicações para mudanças climáticas futuras

Brazil is today the world's second largest soybean producer, and the crop is cultivated throughout the country. However, this was not always the case. The most productive soybean regions of today were deemed unsuitable for soybean planting until the 1970's, and the crop was limited to southern Brazil. The new regions were incorporated into production only after significant technological developments on soybean breeding and management practices. The expansion of soybeans into those areas represented a major change in the climate experienced by the plants, and provides important lessons on adaptation to future climate change. This work aims to overcome limitations of data on yields, area and planting dates in order to perform a large-scale quantitative assessment of the changes in climate, photoperiod and technology experienced by soybeans during the expansion, and compare them with future climate expectations. A spatially explicit dataset on soybean harvested area and yields is developed. The photoperiod limitations to the planting date of each year's varieties are estimated using the northernmost latitude where soybeans were planted. This information is combined with spatial rainy season onset and end to obtain spatial and temporal estimates of the planting window for the period 1974- 2012. The estimates compare well with planting dates recommended by the literature. With the development of photoperiod-insensitive varieties, planting windows went from being limited by the photoperiod on most of soybean-producing Brazil in 1974 to be limited by the rainy season in 1984. This development also had the effect of flexibilizing planting dates, making feasible the double cropping systems common today in central Brazil. Soybeans moved to much wetter regions, as total change in average excess precipitation (P-ETC) found was 2.33 mm day -1 on the historical period (1974-2012). Average temperatures rose at a rate of 0.49 °C decade -1 during the expansion, 0.29 °C decade -1 being due to local trends, faster than the expected rate for 2013-2050 (0.35 °C decade -1 ). The highest yields were also achieved in the warmer regions. Funding and coordinating agricultural R&D towards unified goals is likely to be an efficient strategy to adapt Brazilian agricultural systems to climate change, and may bring many beneficial side effects.O Brasil é hoje o segundo maior produtor de soja do mundo, e a cultura é plantada por todo o país. Porém, nem sempre foi assim. As regiões atualmente mais produtivas eram consideradas inaptas para o cultivo da soja nos anos 1970, e a cultura era limitada à região Sul. As novas regiões foram incorporadas à produção apenas depois de desenvolvimentos significativos em melhoramento genético e práticas de manejo. A expansão da soja para essas áreas representou uma grande mudança no clima a que as plantas foram submetidas, e traz importantes lições sobre adaptação às mudanças climáticas futuras. O objetivo deste trabalho é superar a limitação de dados sobre área, produtividade e épocas de plantio para realizar uma avaliação quantitativa em larga escala das mudanças no clima, fotoperíodo e tecnologia da soja durante a expansão e compará-las a expectativas para o clima futuro. É desenvolvido um banco de dados espacialmente explicito de área colhida e produtividade de soja. São estimadas as limitações fotoperiódicas ao plantio das variedades de cada ano usando a latitude mais ao norte onde a soja foi colhida. Essa informação é combinada com dados espacializados de início e fim da estação chuvosa para obter estimativas espaciais e temporais da janela de plantio para o período 1974-2012. As estimativas são consideradas adequadas quando comparadas com datas de plantio recomendadas na literatura. As janelas de plantio da maior parte das regiões produtoras de soja no Brasil eram limitadas pelo fotoperíodo em 1974. Com o desenvolvimento de variedades insensíveis ao fotoperíodo, passaram a ser majoritariamente limitadas pela estação chuvosa em 1984. Esse desenvolvimento também teve o efeito de flexibilizar as datas de plantio, tornando possíveis os sistemas de dupla safra que hoje são comuns no Brasil central. O cultivo da soja se moveu para regiões bem mais chuvosas, sendo a mudança total no excesso de precipitação (P-ETC) de 2.33 mm dia -1 no período 1974-2012. A temperatura média aumentou a uma taxa de 0.49 °C década -1 nesse período, sendo 0.29 °C década -1 devido a tendências locais, mais rápido do que a taxa de aquecimento esperada para 2013-2050 (0.35 °C década -1 ). As produtividades mais altas foram obtidas nas regiões mais quentes. O financiamento e principalmente a coordenação das instituições de pesquisa e desenvolvimento agrícola na direção de objetivos comuns é provavelmente uma estratégia eficiente para adaptar os sistemas agrícolas brasileiros às mudanças climáticas, e deve trazer diversas externalidades positivas.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Interações entre desmatamento e composição atmosférica no clima da Amazônia e do Cerrado e suas consequências para a agricultura

razilian crop production has managed to grow expressively in the last 15 years with relatively little conversion of natural vegetation. Deforestation in the major Brazilian biomes however is still far from zero, and rates have been going up with the recent dismantling of public environmental governance (EG). Deforestation leads to changes in regional climate, which along with global climate change affects crop yields, often negatively. EG can benefit production by minimizing these effects. This thesis investigates how interactions between deforestation-induced and global climate change can affect Brazilian double cropping systems. These systems in Brazil play an important role on global grain production. Although modelling studies have suggested that they can be severely affected by global climate change, there’s little empirical understanding of their sensitivity to climate. Chapter 1 examines how past climate variability affected municipality-level statistics of soybeans and second crop maize yields and double cropping adoption, and evaluate the impacts of projected global changes in climate. Double cropping in parts of Brazil with strong precipitation seasonality is more likely to occur when the rainy season is larger than 200 days, with no DC in municipality-years below 150 days. CMIP6 models project years with the rainy season shorter than 200 days to be more likely by 2035-2050 under the SSP2-4.5 scenario in key double cropping regions in central Brazil. Soybean yields are projected to decline by ~12%, a result that is not substantially affected by yield model specification. Second crop maize yields are found to be less sensitive to changes in climate than soybeans, with no significant impacts on the country average. However, models that explicitly account for vapor pressure deficit project substantial (>10%) impacts on second crop maize yields in regions with projected rainy season shortening. Chapter 2 uses a fully coupled climate system model and the empirical yield models from Chapter 1 to evaluate how different plausible EG futures can affect the Brazilian production of soybeans and 2nd crop maize. We perform simulations combining two land use scenarios representing different levels of EG and two global climate change scenarios (RCPs 2.6 and 8.5). We find that soybean yields are negatively affected in all scenarios, but differences in EG can impact yields as much as differences in atmospheric composition (RCPs). Stronger environmental governance can prevent soybean production losses equivalent to 442-527 million USD year -1 in the Amazon and 670-1347 million USD year -1 in the Cerrado by 2050, up to 10% of projected production. Collectively, Brazilian soybean farmers have much to gain with better environmental governance and it would be in their interest to enforce and even extend private zero-deforestation agreements in the Amazon and Cerrado biomes. Keywords: Double cropping. Statistical crop model. Climate change. Brazil. Deforestation. Biogeophysical climate change. Land use and land cover change. Earth system modelsA produção de grãos no Brasil cresceu expressivamente nos últimos 15 anos com relativamente pouca conversão de vegetação natural. Porém, taxas de desmatamento nos principais biomas brasileiros ainda estão longe de zero, e vem crescendo com o recente desmantelamento da governança ambiental (GA) pública. O desmatamento leva a mudanças no clima regional, que juntamente com mudanças climáticas globais afetam a produtividade agrícola. Uma boa governança ambiental pode beneficiar a produção agrícola minimizando esses efeitos. Esta tese investiga como interações entre mudanças climáticas globais e induzidas pelo desmatamento podem afetar os sistemas de dupla safra no Brasil. Esses sistemas tem um papel importante na produção mundial de grãos. Apesar de estudos de modelagem sugerirem que eles podem ser severamente afetados por mudanças climáticas globais, ainda há pouca compeensão empírica de sua sensibilidade ao clima. O Capítulo 1 examina como variações no clima passado afetaram a produtividade de soja e milho segunda safra e a adoção de dupla safra por município, e avalia os impactos de projeções de mudanças climáticas globais nesses sistemas. A adoção de sistemas de dupla safra em regiões do Brasil com forte sazonalidade da precipitação ocorre com mais frequência onde a estação chuvosa dura mais de 200 dias, e não foi observada em nenhum município e ano onde ela durou menos de 150 dias. Modelos do CMIP6 indicam que anos com a estação chuvosa menor que 200 dias ocorrerão com mais frequência em 2035-2050 no cenário SSP2-4.5 em regiões chave que praticam dupla safra no Brasil. A produtividade de soja deve diminuir ~12% no mesmo período, um resultado que não é afetado substancialmente pela escolha de especificação dos modelos. A sensibilidade da produtividade de milho segunda safra ao clima parece ser menor do que a de soja, com impactos médios no país não sendo estatisticamente significativos. Porém, modelos que explicitamente consideram o efeito do déficit de pressão de vapor indicam impactos substanciais (>10%) em regiões onde a estação chuvosa deve se encurtar. No Capítulo 2, um modelo acoplado do sistema climático é usado em combinação com os modelos de produtividade estimados no Capítulo 1 para avaliar como diferentes futuros plausíveis da governança ambiental no Brasil podem afetar a produção de soja e milho segunda safra usando cenários de uso do solo representando dois níveis de GA e dois cenários de mudanças climáticas globais (RCPs 2.6 e 8.5). A produtividade de soja é negativamente afetada em todos os cenários, mas diferenças entre cenários de GA podem afetar a produtividade tanto quanto diferenças entre os RCPs. Uma governança ambiental mais forte pode prevenir perdas de produção de soja equivalentes a 442-527 milhões de USD por ano na Amazônia e 670-1347 milhões de dólares por ano no Cerrado, até 10% da produção total projetada para 2050. Coletivamente, produtores de soja brasileiros tem muito a ganhar com uma governança ambiental forte, e seria do interesse deles aplicar ou até expandir acordos de desmatamento zero na Amazônia e no Cerrado. Palavras-chave: Sistemas de dupla safra. Safrinha. Modelo de produtividade. Mudanças climáticas. Desmatamento. Efeitos biogeofísicos no clima. Mudança de uso e cobertura do solo. Modelos do sistema terrestreConselho Nacional de Desenvolvimento Científico e Tecnológic

A possible deforestation-induced synoptic-scale circulation that delays the rainy season onset in Amazonia

The physical hydroclimate system of the Amazon functions on several spatial and temporal scales. Large-scale processes control the main seasonal patterns of atmospheric circulation and rainfall. Seasonal variability in solar forcing, associated with the low rainforest albedo, provides energy for continental heating, convection, and the onset of the South American monsoon. Mesoscale processes cause localized circulations such as river breeze and deforestation breeze. We assessed the impact of different deforestation scenarios for the mid-century last decade rainy season. Here we describe a yet unreported synoptic-scale circulation that delays the rainy season onset in southern Amazonia. This model-predicted circulation is driven by extensive (ca. 40%) deforestation patterns and may last as long as two months. This persistent anomalous circulation may result in a rainy season onset delay of 30–40 d compared to the historical period. Like other synoptic-scale phenomena, differences in surface heating drive this circulation. Given the unabated deforestation trends, the consequences for local ecosystems, agriculture, and power generation of delayed rainy season onset associated with this circulation may be difficult to revert

Amazon Hydrology From Space: Scientific Advances and Future Challenges

International audienceAs the largest river basin on Earth, the Amazon is of major importance to the world's climate and water resources. Over the past decades, advances in satellite-based remote sensing (RS) have brought our understanding of its terrestrial water cycle and the associated hydrological processes to a new era. Here, we review major studies and the various techniques using satellite RS in the Amazon. We show how RS played a major role in supporting new research and key findings regarding the Amazon water cycle, and how the region became a laboratory for groundbreaking investigations of new satellite retrievals and analyses. At the basin-scale, the understanding of several hydrological processes was only possible with the advent of RS observations, such as the characterization of "rainfall hotspots" in the Andes-Amazon transition, evapotranspiration rates, and variations of surface waters and groundwater storage. These results strongly contribute to the recent advances of hydrological models and to our new understanding of the Amazon water budget and aquatic environments. In the context of upcoming hydrology-oriented satellite missions, which will offer the opportunity for new synergies and new observations with finer space-time resolution, this review aims to guide future research agenda toward integrated monitoring and understanding of the Amazon water from space. Integrated multidisciplinary studies, fostered by international collaborations, set up future directions to tackle the great challenges the Amazon is currently facing, from climate change to increased anthropogenic pressure

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data