ArtigoManaging ecosystem services in the Brazilian Amazon: the influence of deforestation and forest degradation in the world's largest rain forest

AbstractThe Amazon rain forest covers an area of ~ 6.7 million km2 of South America; nearly 60% of it is in Brazil, while the rest is shared among eight other countries. This vast extent of rain forest is a globally significant ecosystem that provides numerous ecosystem services that benefit humanity including essential climate regulation, biodiversity conservation, and hydrological stability. However, deforestation and forest degradation have led to the loss of approximately 15% of the Amazon rainforest since the 1970s, primarily driven by agricultural expansion, illegal mining, logging, and wildfires. These pressures have triggered a cascade of consequences, including biodiversity loss, disruption of cultural and ecosystem services, depletion of carbon sinks, and severe alterations to the hydrological cycle. While initially manifesting at local and regional scales, these effects increasingly pose risks to global climate stability. We simulated deforestation scenarios (15%, 50%, and 100% forest loss) using the Community Atmosphere Model (CAM 3.1) to evaluate precipitation changes and atmospheric responses. Results indicate substantial reductions in regional precipitation, hydrological disruptions affecting agricultural productivity, and an increasing risk of the Amazon transitioning from a carbon sink to a carbon source. This underscores the urgency of policy interventions, including stricter environmental regulations, trade restrictions on commodities produced illegally or in deforested areas, enhanced Indigenous land protection, and international cooperation to mitigate deforestation and promote sustainable land use. Immediate action is necessary to prevent irreversible ecological and climatic tipping points.

ArtigoAssessing the impacts of South Atlantic Convergence Zone (SACZ) and atmospheric blockings on rainfall variability in Brazilian biomes using Standard Precipitation Index (SPI)

AbstractClimate change is disrupting atmospheric patterns, which, in turn, alters precipitation regimes worldwide. Droughts are becoming more frequent, intense, prolonged, and spatially distributed, posing a threat to water security for millions of people. Drought monitoring is particularly critical in Brazil, a country that encompasses diverse climate regimes and biomes, and where rainfall variability greatly impacts social vulnerabilities, biodiversity, and the economy. To better understand disruptions in rainfall patterns leading to drier conditions in Brazil, we evaluated the correlation between the occurrence of atmospheric blockings and episodes of the South Atlantic Convergence Zone (SACZ) with rainfall variability, particularly for droughts, in various biomes. The Standardized Precipitation Index (SPI) was used to characterize precipitation variability, presenting simple yet robust statistical insights into the distribution, duration and frequency of rainfalls surpluses (positive values) and droughts (negative values). The SPI values for 1, 6 and 12 months were calculated using observed rainfall data from the Brazilian Daily Weather Gridded Data (BR-DWGD) database, from 1961 to 2024. SACZ episodes and atmospheric blocking events were identified using indices developed by LAMMOC/UFF research group, which effectively describe the behaviour of these systems across various regions of the country. The atmospheric blocking index was calculated using ERA5 reanalysis data, while NCEP reanalysis data was the input to the SACZ index. All data were normalized prior to statistical analyses, which included Pearson's correlation coefficient, Principal Component Analysis (PCA), K-means clustering, Mann-Kendall test, and trend analysis to identify and quantify trends. The results demonstrate that atmospheric blocking events are increasing in all regions of Brazil. Conversely, the SACZ occurrences did not demonstrate a significant trend. The correlation between atmospheric blockings and SPI values exhibit a strong pattern in all evaluated time scales and regions, demonstrating significant positive influence in the Pampa biome within all evaluated time scales, suggesting that blockings, regardless of their position, incur in rainfall surpluses in South Brazil. In the other biomes, blockings show a consistent negative influence, particularly in Cerrado, Pantanal and Amazonia (Central and Northern regions). Cerrado shows correlations of up to -0.5, the highest values observed in the analysis - suggesting atmospheric blockings have an inhibiting effect in precipitation, creating drier conditions that are concerning for wildfire hazard in central Brazil, and also in Southern Amazonia. SACZ and SPI correlation is not as clear, with small to no trend in most biomes, except for the slight negative influence on the Pampa, region where precipitation decreases as active SACZs concentrate rainfall northward. Understanding the correlation between these important atmospheric systems and the precipitation variability observed in Brazil is valuable to drought monitoring and prediction, and may help to identify early warning signals for major droughts, providing insights that can guide mitigation and adaptation strategies to address the impacts of climate change, which affects differently the regions of the country due to the complexity of its diverse climate regimes and biomes, and therefore, water availability and wildfire hazard.

ArtigoForecasting Cut-Off Lows Events with MPAS: A Study of Valencia's Historic Rainfall in October 2024

AbstractBetween 29 and 30 October 2024, Spain experienced one of the most intense and destructive natural disasters in its history, predominantly affecting the Valencian Community but also parts of the Murcia region and the province of Albacete. The floods impacted approximately 75 municipalities, affecting over 400,000 inhabitants, damaging around 100,000 homes and 137,000 vehicles, and resulting in a total of 232 fatalities across Spain, 224 of which occurred in the province of Valencia alone. This extreme meteorological event not only recorded the highest rainfall accumulation in Spain's history, with 771.8 mm in just 14 hours at the Túris station in Valencia but also highlighted inefficiencies in the authorities' ability to convey extreme danger alerts to the population. The State Meteorological Agency (AEMET) issued the alert at 07:36 on 29 October, but it was passed on by the local authorities only 20:11, approximately 12 hours after the event started and the onset of precipitation, which significantly increased the risk to the population. In this study, simulations were conducted using the NCAR/MPAS model with a global resolution mesh of approximately 92 km, which converged to a finer mesh centred on Spain with a resolution of 25 km. The resolution increase was smoothed due to the numerical scheme used by the model, which employs Voronoi hexagons. The MPAS was initialised with initial conditions from the NCEP/NOAA dataset, obtained at 00Z for the period 23-29 October 2024. The study aimed to evaluate how far in advance it would have been possible to predict the configuration and position of the centre of the Cut-Off Low (DANA), the atmospheric phenomenon responsible for the extreme precipitation totals. The goal was to determine how early the risk associated with the DANA could have been identified, regardless of the precipitation totals forecasted by the model, focusing solely on the atmospheric phenomenon itself. The MPAS simulations revealed that as early as 24 October, the DANA configuration could be identified, based not only on the position of its vorticity centre at 500 hPa but also on the intense moisture transport at 850 hPa originating from the Mediterranean, which surface temperature was approximately 2-3°C above its average, directed towards the Valencian region. This pattern persisted in all simulations initialised between 24 and 29 October, with some precipitation cores showing accumulations of 200-300 mm between 29 and 30 October in the Valencian region. Thus, this study encourages reflection on the extent to which meteorology should rely on precipitation totals forecasted by atmospheric models when issuing alerts and warnings, or whether such alerts could instead be guided by the configuration of specific atmospheric phenomena. This approach could potentially increase lead times, as forecasting wind fields generally involves lower uncertainty compared to precipitation. Such an increase in lead time could be crucial to save lives in extreme weather events like this one.

ArtigoDeveloping a Multivariate System for Predicting and Mitigating the Health Effects ofHeat waves in Niterói, Rio de Janeiro

AbstractThis study aims to develop a heat wave forecasting system using a new multivariate index that encompasses hydration-related mitigation measures. Heatwaves have increasingly occurred with greater frequency and intensity in various regions worldwide, particularly in Europe and Asia since 1990, although they are not exclusive to these areas. The principal health effects of heatwaves on populations include heat-related illnesses and fatalities, cardiovascular and kidney diseases, as well as adverse reproductive effects. These detrimental impacts are widespread and commonly affect individuals aged 65 and above. Many nations have established metrics to assess the prevalence of this occurrence within their borders. These metrics typically utilize specific thresholds and/or temperature ranges at a height of 2 meters, which denote extreme percentiles of values from past records. While some of these metrics consider the persistence of the phenomenon, few take into account the relative humidity. It is noteworthy that, in most instances, the temperature thresholds lead to a linear escalation in conditions posing a risk to the population. This can result in a biased perception of the actual level of risk involved. To thoroughly evaluate the health hazards associated with heatwaves, it is essential to acknowledge the considerable variability in global climate, as well as the diverse responses of living organisms to extreme temperature and humidity conditions. Furthermore, factors such as individuals' gender, race, age, pre-existing medical conditions, and geographical location should be taken into account.This study is divided into several components to reach a comprehensive solution. The first step involves determining the monthly distribution curve of accumulated daily maximum temperatures for each grid point of the ERA 5 data. After completing this process, machine learning models must be developed to calibrate the temperature values to the percentile of the cumulative distribution. Subsequently, the temperature value exceeding 95% of the distribution will be applied to this coefficient Coef = (eTpe*Ur)/1000, where Tpe is the value of the distribution that exceeds 95% and Ur is the relative humidity. These adjusted values will then be used to compute the normalized index I=(Coef-0.022)/9.7, accounting for the exponential temperature increase and providing weightage to the relative humidity. Upon establishment of these functions, a time series of the index value will be generated. This value will be multiplied by the hours of the day during which the index deviates from zero, facilitating the evaluation of its correlation with hospitalization and mortality data related to diseases such as thrombosis, which may be linked to heat waves. The results of this phase will be presented at the Niterói region in Rio de Janeiro, Brazil, during the upcoming congress. Moreover, according to previous analyzes, since 2010 the frequency and intensity of heat waves have increased, being apparently modulated by Enso events and also by indices developed at LAMMOC/UFF related to anomalies of sea surface temperature of the Equatorial Atlantic Ocean and the South Atlantic Convergence Zone. Furthermore, the index data will subsequently undergo validation based on body water loss rates and their impact on blood viscosity fluctuations.

ArtigoInfluence of Atmospheric Blocking and SACZ Episodes on Extreme Heatwaves in Brazil: A Long-Term Analysis

AbstractRising temperatures driven by climate change pose significant challenges worldwide. In Brazil, these challenges include extreme weather events such as heatwaves, which can have severe health impacts. This study investigates the influence of atmospheric blocking events and episodes of the South Atlantic Convergence Zone (SACZ) on Brazil's occurrence and intensity of extreme heatwaves. Atmospheric blocking and SACZ episodes were characterized using indices developed at LAMMOC/UFF, which effectively capture the behavior of these systems across different regions of the country. Atmospheric blocking events are typically associated with prolonged droughts, while SACZ episodes are linked to intense, spatially well-distributed precipitation. The newly developed Extreme Heatwave (XHW) index was applied in this study due to its global applicability, covering all 26 state capitals and the Federal District of Brazil. The SACZ index was calculated using NCEP Reanalysis data (I and II) while blocking and XHW indices were calculated using ERA5 reanalysis data, generating a time series from 1960 to 2024. To facilitate statistical analyses, all data were normalized. Methods such as Pearson's correlation coefficient, Principal Component Analysis (PCA), K-means clustering, trend analysis, and the Mann-Kendall test were applied to identify and quantify trends in the series. The results showed an increase in extreme heat events in most cities, except for Florianópolis (in the South) and Fortaleza (in the Northeast), which displayed no significant trend. Atmospheric blockings also showed a clearer upward trend across all evaluated regions compared to SACZ episodes. The correlation between the SACZ and heatwaves is statistically insignificant across most of Brazil, with values close to zero, as the SACZ is not associated with significant temperature gradients, causing little to no impact on the occurrence of heatwaves. In contrast, atmospheric blockings show statistically significant positive correlations with heatwaves, particularly in geographically specific regions. For example, in the North region, Palmas (TO) stands out with a correlation of 0.44, while Manaus (AM) approaches a value of 0.38. These cities are more responsive to northern-located blockings. Rio de Janeiro (RJ), in the Southeast, and Cuiabá (MT), in the Central-West, exhibit a correlation of 0.37 due to southern and northern-located blockings, respectively. In the South, Porto Alegre (RS) is the most responsive to southern-located blockings with a correlation of 0.18. In the Northeast, values are generally low, with Recife (PE) showing the highest correlation (0.16) for northern-located blockings. This study emphasizes the importance of spatial analysis in understanding the influence of atmospheric blockings on extreme heatwaves events, revealing a direct relationship between the position of blockings and their impact, as evidenced by the varying responses of different cities. As atmospheric blockings increase in frequency due to climate change, heatwaves are also expected to become more frequent and intense. This trend poses a growing risk to public health and mortality, as well as significant challenges to the healthcare system.

ArtigoThe Role of Teleconnection Indices in Modulating Rainfall and Drought in Central Brazil

AbstractIncreasing temperatures due to climate change pose challenges to countries worldwide, including Brazil, where extreme weather may result in biodiversity loss, water resource availability changes, and significant economic and health impacts. This study evaluates the influence of various teleconnection indices on the variability patterns of atmospheric blocking events occurring in central Brazil and episodes of the South Atlantic Convergence Zone (SACZ). Nearly all teleconnection indices made available in the NOAA's website were analysed, including those related to the Pacific, Atlantic, Indian Oceans and global-scale indices. Additionally, four new indices were explicitly developed for this study, focusing on NOAA's OISST Sea Surface Temperature anomalies in the North Atlantic Ocean near the Moroccan coast. The characterization of atmospheric blocking events and SACZ episodes was carried out using indices developed at LAMMOC/UFF, which effectively capture the behaviour of these atmospheric systems across different regions of Brazil. The SACZ index was calculated using NCEP Reanalysis data, while the atmospheric blocking index used ERA5 reanalysis data, resulting in a time series spanning from 1981 to 2023. All data were normalized for statistical analyses, and methods including Pearson's correlation coefficient, Principal Component Analysis, K-means clustering techniques, trend analysis, and the Mann-Kendall test were applied to identify and quantify trends in the data. Atmospheric blocking and SACZ episodes have contrasting yet significant influences on the rainfall in central Brazil. Atmospheric blocking events are typically associated with prolonged droughts, whereas SACZ episodes are linked to intense and spatially well-distributed precipitation. This region is vital for the country's agriculture, industry, and energy production. The analysis revealed that a significant portion of oceanic indices from the Atlantic and the Pacific Oceans, along with atmospheric blocking events, exhibit strong increasing trends. These trends are accompanied by positive correlations, observed in the trend-inclusive and detrended series. For instance, correlations reach 0.7 values with the Global Mean Land/Ocean Temperature, 0.45 with ENSO indices, 0.55 with North Atlantic indices near the Moroccan coast, and 0.67 with the Pacific Warmpool Area Average. In contrast, the SACZ index showed no clear trend in the Mann-Kendall tests. Correlations between SACZ and the same oceanic indices often exhibited an inverse relationship compared to those with blocking indices and were also generally weaker, ranging between -0.15 and -0.30. One exception was a positive correlation of around 0.34 with the East Pacific/North Pacific Oscillation index. Overall, the study highlights that atmospheric blocking events are becoming increasingly frequent and intense in central Brazil, closely following the warming trend of the oceans. This poses a warning for the region's hydrometeorological regime. While the absence of an evident decline in SACZ episodes provides some relief, the escalating deforestation in the Amazon, one of the primary sources of moisture driving precipitation during SACZ episodes, may become the decisive factor in altering the region's precipitation patterns, potentially exacerbating the ongoing water crisis in central Brazil.

ArtigoTeleconnection Patterns and Synoptic Drivers of Climate Extremes in Brazil (1981-2023)

ResumoO Brasil é cada vez mais afetado por eventos climáticos extremos devido às mudanças climáticas, com diferenças regionais pronunciadas nos padrões de temperatura e precipitação. A região Sudeste é particularmente vulnerável, experimentando frequentemente secas severas e ondas de calor extremas ligadas a eventos de bloqueio atmosférico e episódios de chuvas intensas impulsionados pela Zona de Convergência do Atlântico Sul (ZCAS). Esses fenômenos contribuem para desastres climáticos recorrentes. A forte dependência do país em energia hidrelétrica aumenta sua suscetibilidade a secas, enquanto evidências crescentes apontam para a intensificação de períodos de seca e incêndios florestais em várias regiões, ameaçando a produção agrícola e a segurança alimentar. As áreas urbanas, em particular, estão experimentando ondas de calor mais frequentes e severas, representando sérios riscos à saúde de populações vulneráveis. Este estudo investiga as ligações entre índices globais de teleconexão e sistemas em escala sinótica, especificamente eventos de bloqueio e atividade da ZCAS, e suas influências no calor extremo do Brasil, nas condições de seca e na variabilidade do fluxo dos rios nos últimos 30 a 40 anos. Ao esclarecer essas interações, a pesquisa visa aumentar a compreensão de como a dinâmica atmosférica em larga escala molda os extremos climáticos e avaliar suas implicações mais amplas para a gestão de recursos hídricos, produção de energia e variabilidade climática regional.

ArtigoWould the occurrence of a Maunder-like solar minimum reverse the observed climate change?

ResumoEste estudo examina um cenário que combina um mínimo solar prolongado, como o histórico Mínimo de Maunder, com o aumento das emissões de CO2 característico da era industrial. Dois cenários foram desenvolvidos no NCAR/CESM 2.0 implementado no LAMMOC/UFF para criar simulações de 1850 a 2000, contrastando diferentes forçantes radiativos de 1950 em diante — um refletindo mudanças reais observadas, incluindo o aumento dos níveis de CO2, e o outro simulando uma diminuição na produção solar como aquela durante o Mínimo de Maunder, mas com crescimento contínuo de CO2. Os resultados foram validados com base em dados do ERA5 e reanálises do século XX. Calculando médias meridionais em intervalos de latitude de 30 graus, foram identificados impactos regionais distintos do Mínimo de Maunder. Notavelmente, o Mínimo de Maunder simulado reduziu o aquecimento global e até mesmo mitigou 70% no HS na última década do século XX. Entretanto, essa atenuação foi menor no HN, especialmente na região 30-60N, onde nenhuma atenuação foi observada.