Abstract
Land use change and deforestation can influence local temperature and climate. Here we use a coupled ocean-atmosphere model to assess the impact of savannization of the Amazon Basin on the ...wet-bulb globe temperature heat stress index under two climate change scenarios (RCP4.5 and RCP8.5). We find that heat stress exposure due to deforestation was comparable to the effect of climate change under RCP8.5. Our findings suggest that heat stress index could exceed the human adaptation limit by 2100 under the combined effects of Amazon savannization and climate change. Moreover, we find that risk of heat stress exposure was highest in Northern Brazil and among the most socially vulnerable. We suggest that by 2100, savannization of the Amazon will lead to more than 11 million people will be exposed heat stress that poses an extreme risk to human health under a high emission scenario.
Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of ...enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest both the possibility of significant changes in large-scale aspects of circulation as well as improvements in small-scale processes and extremes. However, such high-resolution global simulations at climate timescales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centres and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other model intercomparison projects (MIPs). Increases in high-performance computing (HPC) resources, as well as the revised experimental design for CMIP6, now enable a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal-resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is divided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950–2050, with the possibility of extending to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulations. HighResMIP thereby focuses on one of the CMIP6 broad questions, “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.
Land use change and atmospheric composition, two drivers of climate change, can interact to affect both local and remote climate regimes. Previous works have considered the effects of greenhouse gas ...buildup in the atmosphere and the effects of Amazon deforestation in atmospheric general circulation models. In this study, we investigate the impacts of the Brazilian Amazon savannization and global warming in a fully coupled ocean-land-sea ice-atmosphere model simulation. We find that both savannization and global warming individually lengthen the dry season and reduce annual rainfall over large tracts of South America. The combined effects of land use change and global warming resulted in a mean annual rainfall reduction of 44% and a dry season length increase of 69%, when averaged over the Amazon basin, relative to the control run. Modulation of inland moisture transport due to savannization shows the largest signal to explain the rainfall reduction and increase in dry season length over the Amazon and Central-West. The combined effects of savannization and global warming resulted in maximum daily temperature anomalies, reaching values of up to 14 °C above the current climatic conditions over the Amazon. Also, as a consequence of both climate drivers, both soil moisture and surface runoff decrease over most of the country, suggesting cascading negative future impacts on both agriculture production and hydroelectricity generation.
Polyamide creates high-performance composite materials, which are replacing the traditional epoxy composites in several applications. In this context, exposure to hostile environments is expected. On ...the other hand, due to the viscoelastic nature of the matrix, these composite materials are prone to stress relaxation. Therefore, the stress relaxation behaviour of glass/polyamide 6 composites was studied considering different fibre directions, as well as exposure to NaOH and HCl solutions. Stress relaxation tests on the bending mode were carried out, and the stress recorded during the loading time (7200 s). All tests were characterized by a stress decrease over time, but laminates with higher fibre angles were more prone to stress relaxation. However, exposure to hostile solutions promoted more significant decreases, where the highest stress relaxation was achieved for alkaline environments with values that were three times higher for laminates with fibres at 0° and around one and half times higher for 45° fibre alignments when compared with the control samples. Finally, the Kohlrausch-Williams-Watts (KWW) model showed that it can be used to predict stress relaxation time, due to the accuracy that was obtained between the experimental and theoretical results.
Abstract
This study presents novel insight into the mechanisms of Atlantic Meridional Overturning Circulation (AMOC) reduction and its recovery under a warmer climate scenario. An ...one-thousand-year-long numerical simulation of a global coupled ocean–ice–atmosphere climate model, subjected to a stationary atmospheric radiative forcing, depict a coherent picture of the Arctic sea ice melting as a trigger for the initial AMOC reduction, along with decreases in the northward fluxes of salt and heat. Further atmospheric-driven ocean processes contribute to an erosion of the stable stratification of the fresher, yet colder waters in the surface layers of the North Atlantic, contributing to the recovery of a permanently altered AMOC.
The body colour variation in response to different background colours is associated with camouflage, increasing efficiency against predation. In our study, we investigated the body colour variation ...of the freshwater shrimp Macrobrachium jelskii in response to different background colours. For this, we collected specimens of M. jelskii in the Thomás Osterne Reservoir, Municipality of Crato, State of Ceará, Brazil. For the experiment, we used six aquariums divided into three treatment groups: white background; black background; red background; with two replicates for each group. Before the experiment, we photographed 30 specimens of M. jelskii in dorsal view. Then, we distributed five shrimps in each aquarium, totalling 10 shrimps per treatment. After 30 days, we obtained new images of the shrimps, under the same settings used before the experiment. We used ImageJ software to obtain the RGB values (Red, Green, Blue) of the dorsal region of the first abdominal somite of the shrimps. Before the experiment, the body pigmentation of M. jelskii was homogeneous, with overlap between the groups. After the experiment, the RGB of M. jelskii varied according to each background colour, differing between the white and black, between the white and red, and not differing between the black and red. Our results show that M. jelskii adjusted its pigmentation to different background colours, evidencing a mechanism that may favour the camouflage of the species in different habitats and provide more chances of survival against visual predators.
In this paper an experimental investigation on fire retardancy of a new polymer nanocomposite derived from organic montmorillonite and exolit fire retardant in an acrylonitrile- butadiene-styrene ...copolymer by analyzing the flammability and fire behavior is described. The samples were prepared by melting and mixing nanocomposites and fire retardant in different concentrations in an acrylonitrile-butadiene-styrene base polymer. It was found that using only one component (organic montmorillonite or fire retardant) the burning stops in 10 s on the sample. Confirmation of synergy in flammability by combining both montmorillonite and flame retardants was noticed and is discussed regarding the flame-retardant mechanisms assessed by means of the Limiting oxygen index (LOI), UL 94, and cone-calorimeter methods. The acrylonitrile- butadiene-styrene preparation with 15–20 wt% fire retardant and 1–2 wt% organic montmorillonite reached a UL-94 V-0 classification, contrasting with the pure acrylonitrile- butadiene-styrene and the acrylonitrile-butadiene-styrene with 15 wt% fire retardant and acrylonitrile-butadiene-styrene with 1–2 wt% organic montmorillonite formulations, which completely burned. Finally, the samples showed a very good synergy going to a higher reduction of the peak heat release rate and to a minimum mass reduction, as obtained from cone calorimeter tests.
The expansion of areas of human occupation and the increase in economic activity and deforestation are negatively impacting the Amazon ecosystem. Situated in the Carajás Mineral Province in the ...southeastern Amazon, the Itacaiúnas River Watershed (IRW) encompasses several active mines and has a historical record of intense deforestation primarily linked with the expansion of pasturelands, but also of urban areas, and mining activities. Industrial mining projects are subjected to strict environmental control, but artisanal mining (ASM; ‘garimpos’) sites have not been controlled, despite their known environmental impacts. In recent years, the opening and expansion of ASM in the IRW for the exploitation of mineral resources (Au, Mn, and Cu) have been remarkable. This study presents evidence of anthropogenic impacts, mainly caused by ASM, on the quality and hydrogeochemical characteristics of the IRW surface water. The hydrogeochemical data sets of two projects carried out in the IRW, during 2017 and from 2020 until present, were used to evaluate these impacts within the region. Water quality indices were calculated for the surface water samples. For the whole IRW, water collected during the dry season tended to yield better quality indicators in comparison to those collected during the rainy season. Two sampling sites at Sereno Creek showed very poor water quality and extremely high concentrations of Fe, Al, and potentially toxic elements over time. From 2016 to 2022, ASM sites increased markedly. Moreover, there are indications that Mn exploitation via ASM in Sereno hill is the main source of contamination in the area. New trends of ASM expansion were observed along the main watercourses, related to the exploitation of Au from alluvial deposits. Similar anthropogenic impacts are registered in other regions of the Amazon and environmental monitoring should be encouraged to assess the chemical safety of strategic areas.
Display omitted
•Climate, pedogeochemistry and land cover influence surface water composition.•Artisanal Mining (ASM) sites of Mn and Au impacted water quality.•ASM sites increased by more than 1500 ha (2883%) from 2016 to 2022.•Potentially toxic element concentrations are greater than background values.•Environmental monitoring of water bodies is mandatory for the Amazon.
Leprosy is a public health problem in Brazil where 31,044 new cases were detected in 2013. Rio Grande do Norte is a small Brazilian state with a rate of leprosy lower than other areas in the same ...region, for unknown reasons.
We present here a review based on the analysis of a database of registered leprosy cases in Rio Grande do Norte state, comparing leprosy's geographic distribution among municipalities with local socio-economic and public health indicators and with historical documents about human migration in this Brazilian region.
The current distribution of leprosy in Rio Grande do Norte did not show correlation with socio-economic or public health indicators at the municipal level, but it appears related to economically emerging municipalities 100 years ago, with spread facilitated by railroads and train stations. Drought-related migratory movements which occurred from this state to leprosy endemic areas within the same period may be involved in the introduction of leprosy and with its present distribution within Rio Grande do Norte.
Leprosy may disseminate slowly, over many decades in certain circumstances, such as in small cities with few cases. This is a very unusual situation currently and a unique opportunity for epidemiologic studies of leprosy as an emerging disease.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study, we investigate the circulation and chemical processes associated with the deposition of the largest oil spill that reached the northeast coast of Brazil during the second half of 2019. ...Using the Oil Spill Contingency And Response model (OSCAR), we performed both deterministic and probabilistic simulations of oil spills from tanker ships that were present in the sea in the region at the time. The study used a dataset comprising the latitudinal distribution of oil sightings along the coast between 31 August and 2 December 2019 (box plot analysis) provided by the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA). The total amount of oil that reached the coast during this period (approximately 5000 tons) and the date and location of the first sighting (30 August, in the southern part of the state of Paraíba (PB)) were also used as parameters to assess the results of the 31 simulations conducted for ships en route near the area of interest between July and August 2019. The results indicate that a leak having occurred through a mobile source is the most plausible hypothesis for explaining the observed temporal–spatial arrival of the oil leaks along the Brazilian coastline. We suggest that prevention, monitoring, and international cooperation are essential for reducing the risks of future environmental accidents of the kind analyzed in this study and to protect the environment and communities affected.
PDF
