A weeklong workshop in Brazil in August 2004 provided the opportunity for 28 scientists from southern South America to examine daily rainfall observations to determine changes in both total and ...extreme rainfall. Twelve annual indices of daily rainfall were calculated over the period 1960 to 2000, examining changes to both the entire distribution as well as the extremes. Maps of trends in the 12 rainfall indices showed large regions of coherent change, with many stations showing statistically significant changes in some of the indices. The pattern of trends for the extremes was generally the same as that for total annual rainfall, with a change to wetter conditions in Ecuador and northern Peru and the region of southern Brazil, Paraguay, Uruguay, and northern and central Argentina. A decrease was observed in southern Peru and southern Chile, with the latter showing significant decreases in many indices. A canonical correlation analysis between each of the indices and sea surface temperatures (SSTs) revealed two large-scale patterns that have contributed to the observed trends in the rainfall indices. A coupled pattern with ENSO-like SST loadings and rainfall loadings showing similarities with the pattern of the observed trend reveals that the change to a generally more negative Southern Oscillation index (SOI) has had an important effect on regional rainfall trends. A significant decrease in many of the rainfall indices at several stations in southern Chile and Argentina can be explained by a canonical pattern reflecting a weakening of the continental trough leading to a southward shift in storm tracks. This latter signal is a change that has been seen at similar latitudes in other parts of the Southern Hemisphere. A similar analysis was carried out for eastern Brazil using gridded indices calculated from 354 stations from the Global Historical Climatology Network (GHCN) database. The observed trend toward wetter conditions in the southwest and drier conditions in the northeast could again be explained by changes in ENSO.
A workshop on enhancing climate change indices in South America was held in Maceió, Brazil, in August 2004. Scientists from eight southern countries brought daily climatological data from their ...region for a meticulous assessment of data quality and homogeneity, and for the preparation of climate change indices that can be used for analyses of changes in climate extremes. This study presents an examination of the trends over 1960–2000 in the indices of daily temperature extremes. The results indicate no consistent changes in the indices based on daily maximum temperature while significant trends were found in the indices based on daily minimum temperature. Significant increasing trends in the percentage of warm nights and decreasing trends in the percentage of cold nights were observed at many stations. It seems that this warming is mostly due to more warm nights and fewer cold nights during the summer (December–February) and fall (March–May). The stations with significant trends appear to be located closer to the west and east coasts of South America.
•Evaluated Brazilian amphibian species rose from 973 to 1096; threatened species increased from 42 to 59 (1st to 2nd assessment).•Threatened species are concentrated in the Atlantic Forest, ...Melanophryniscus is most affected genus.•43 species moved to a higher threat category in the 2nd assessment, mainly due to new information and misinterpretation of criteria.•Amphibians in Brazil face habitat loss and declining quality from agriculture and urbanization.•One-third of threatened amphibians in Brazil lack records in protected areas.
Extinction risk assessments are valuable conservation tools, especially for sensitive groups like amphibians, which are facing escalating threats from habitat loss and degradation. In this scenario, Brazil stands out as a pivotal player in amphibian conservation due to its exceptional amphibian diversity. Between 2010 and 2014, 973 amphibian species were assessed in Brazil. More recently, from 2017 to 2018, this number increased to 1096. In this study, we (1) compare the extinction risk status of Brazilian amphibians between the 1st and 2nd assessments; (2) evaluate the reasons for changes in status; (3) identify the main threats and research recommendations; and (4) analyze the spatial patterns of threatened species in relation to protected areas and ecoregions in Brazil. Our findings reveal an increase in the number of threatened species from the first to the second assessment. The categories of Least Concern and Critically Endangered experienced the most significant increases, with 169 and 16 more species, respectively, while the count of Data Deficient species dropped by 71. The primary factor contributing to these changes is the availability of new, more precise information, affecting 134 species, or 85.4% of the cases. Threatened species are predominantly clustered within the Atlantic Forest biome, itself the most endangered biome in Brazil, hosting 46 species, or 78% of the total. Notably, one-third of threatened species in Brazil do not inhabit protected areas and thus require immediate conservation attention. While substantial progress has been made in understanding Brazilian amphibians in recent years, an urgent need persists for fundamental research. This research should encompass taxonomy, natural history, and the evaluation of threat impacts, providing a robust foundation for more effective conservation efforts concerning this group.
The 1997–1998 El-Niño caused an extreme drought in the northeastern region with considerable losses for agriculture, livestock, water resources and society. Regionally, the impact of these anomalies ...can be striking. In the southeastern region, for example, in the State of São Paulo in the El Niño period, the effects caused by this phenomenon were quite different with above average rainfall in months like May and June. This situation can be observed, as indicated by the rainfall anomalies represented by the monthly Standardized Precipitation Index (SPI) for the month of May in 1998 (Figure 17.1). The occurrence of these anomalies lead the State Government to create a task force involving the various sectors of society, such as, research institutes, universities and the civil defense, to propose mitigation measures.
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