No abstract

Entender a relação da vulnerabilidade social frente aos efeitos da mudança do clima é de suma importância no contexto da adaptação e mitigação dos impactos desta mudança. O objetivo deste estudo foi correlacionar a precipitação (mm) e as temperaturas (ºC) máxima e mínima dos estados do Sudeste brasileiro no período de 2010 a 2019 com o índice de vulnerabilidade social na região. Para isso, caracterizou-se a variabilidade climática da área de estudo, posteriormente relacionando-a com o Índice de Vulnerabilidade Social (IVS) por meio de uma correlação simples de Pearson (r). Os resultados mostraram que, em termos de vulnerabilidade a eventos climáticos, o Sudeste brasileiro é, em geral, mais sensível e suscetível aos danos ocasionados pelas chuvas em comparação aos impactos decorrentes da variação de temperatura na região; e, quanto à correlação entre a variabilidade climática e a vulnerabilidade social, identificou-se relação positiva (valores até +0,51) entre a variabilidade e as chuvas persistentes típicas do fenômeno Zona de Convergência do Atlântico Sul (ZCAS) - reiterando que a precipitação é uma variável meteorológica influente sobre a vulnerabilidade social no Sudeste e que a mudança global do clima pode influenciar negativamente o clima em escala regional e local e trazer danos à sociedade associados à sua resiliência e capacidade adaptativa.

Global climate change and extreme climate variability directly affect the hydrological cycle and rainfall variability, which highlights the importance of studying climatic conditions as a support for water resource management in regions with low water availability, such as the Upper Tietê River Basin (Bacia Hidrográfica do Alto Tietê – BHAT). This study aims to present a diagnosis for BHAT water availability conditions in future climate scenarios, based on the high-resolution models CMCC-CM, MIROC4h, ETA-MIROC5, and ETAHADGEM2- ES, for the time slices 2020-2040, 2041-2070, and 2071-2099, in order to provide climate information for BHAT’s management. The main results showed a clear upward trend in the average annual temperatures. For the RCP8.5 scenario, the average annual increase was 0.5°C from 2006 to 2099. Precipitation showed high interannual variability without a specific defined trend. The average annual flow showed a slight positive trend in the period 2006–2099. However, it also presented a decrease in the monthly average flow in the wet period (13%) and an increase in the dry period (9.7%), compared to the historical data simulated for the time slice 2020–2040 of the RCP8.5 scenario. However, the annual increase in BHAT water availability at future scenarios should not be sufficient to meet the growing demand for water in the region. Therefore, it is necessary to evaluate water availability based on other high-resolution climate models, in order to evaluate uncertainties, and in other regions with different supply systems that provide water to the São Paulo Metropolitan Region, identifying alternative water supply sources.

Cities are increasingly vulnerable to climate change's impacts and poorly adapted to extreme variability. This study aimed to evaluate climate projections of air temperature and precipitation in seven cities in the Metropolitan Region of São Paulo that correspond to the Greater ABC Paulista. We used high-resolution models Eta-HADGEM2_ES (CMIP5), CNRM-CM6-1-HR (CMIP6), and the TerraClimate database to analyze future projections and the specific warming levels (SWLs), respectively. Model data were validated with observed data and bias was removed. A bias correction factor was generated and used in the climate projections for the different emission scenarios. The results show a consensus between the models and the SWLs (2 and 4°C) for the increase in maximum (Tmax) and minimum (Tmin) temperatures for all municipalities in ABC Paulista in different emission scenarios until the end of the 21st century. For the nearest future (2020–2040), the city of São Caetano do Sul (SCS) shows the highest positive annual anomalies of Tmax concerning the climatological period (1985–2015), for the scenario RCP4.5 (2.8°C) and the RCP8.5 (7.4°C), according to projections from the Eta-HADGEM2_ES, highlighting summer and autumn as the hottest. For precipitation, there was a consensus between the Eta-HADGEM2_ES and the CNRM-CM6-1-HR for a reduction in all scenarios and time-slices 2020–2040 and 2041–2070. The municipalities of Diadema (−78.4%) and SCS (−78%) showed the most significant reductions in December for the RCP8.5, and for SSP5-8.5, SCS shows −30.9% in December for the 2020–2040 time-slice. On the other hand, TerraClimate presents excess rain for Ribeirão Pires (+24.8%) and Santo André (+23.7%) in winter for SWL4°C. These results suggest that an increase in Tmax and Tmin, as projected, should influence the intensity of extreme heat events. Furthermore, a reduction in annual and seasonal rainfall does not mean a decrease in the region's extreme daily events that cause floods and landslides. However, it leaves an alert of water scarcity for the supply and demand of the population. ABC Paulista does not have adaptation plans to face extreme climate change. The results can contribute to the first phase of creating an adaptation plan, giving a first view of the climate threat that should intensify until the end of the twentieth century affecting the most vulnerable municipalities.