Hotter, Longer and More Frequent Heatwaves: An Observational Study for the Brazilian City of Campinas, SP

Abstract

Worldwide there is accumulated evidence of heatwave intensification due to climate change. Regional differences in the effects of heatwaves require local studies to implement public mitigation and adaptation strategies. This work analyzes and characterizes heatwaves’ occurrence for the city of Campinas, Brazil, through an observational study from 1956 to 2018. The definition of heatwaves adopted requires that the maximum and minimum daily temperatures be above the daily limits derived from climate normal 1961-1990. The annual and seasonal metrics of the number, frequency, and heatwaves’ duration showed significant and positive trends, except in winter. We found that the longest, the more intense, and the most frequent events occurred in the last 20 years and that a significant change in trend occurred at the beginning of the 1980s. Lastly, we performed an exploratory study of intra-urban variability, comparing heatwave metrics between two different weather stations that are 30 km apart in the city of Campinas. We found similar metrics patterns for the two weather stations, with more prolonged and more frequent heatwave events for the region's station with a higher rate of urban land occupation.

Heat waves in São Paulo State, Brazil: Intensity, duration, spatial scope, and atmospheric characteristics

“…The years 2014, 2015 and 2019 were very hot compared with the average in Brazil. During these years, HW events affected a large part of the Brazilian territory, mainly in the Southeast (Mendes et al, 2022; Oliveira et al, 2021) and South (Alves et al, 2016; Cardoso et al, 2020).…”

“…Oliveira et al (2021) analysed HWs in Campinas, SP State and also found significant and positive trends toward increasing frequency and duration on annual and seasonal scales, except for winter. The authors found that the most prolonged, intense, and frequent events occurred in the last 20 years and that a significant change in trend occurred in the early 1980s.…”

“…It should be stressed that there are few studies of regional and even local scope on HWs. The regional study of HWs and their peculiarities is justified by the need to identify regional differences in their effects, which may guide the implementation of public mitigation and adaptation strategies (Oliveira et al, 2021). Additionally, identifying T max thresholds to define an HW at the subregional and local scales can help create monitoring and alert parameters for populations that are more sensitive to the harmful effects of high temperatures during HWs.…”

Análise da tendência de aumento da temperatura do ar nas cidades de Santa Isabel e São Paulo, estado de São Paulo, a partir de diferentes bases de dados, e levantamento de impactos

“…O estudo mostrou também concordância com as anomalias de temperatura do ar nas escalas regional, continental e global, fornecendo uma evidência científica válida e forte de que as mudanças climáticas ocorreram na cidade nos últimos 100 anos. Oliveira et al (2021) analisaram e caracterizaram a ocorrência de ondas de calor para o município de Campinas, décimo quarto mais populoso do Brasil e o terceiro mais populoso do estado de São Paulo, com o objetivo de investigar seu impacto na saúde. O período analisado foi de 1956 a 2018 e os resultados apontaram para uma mudança significativa na tendência de aumento de temperatura a partir da década de 1980, com eventos mais intensos, mais frequentes e mais prolongados nos últimos 20 anos, coincidindo com a tendência provocada pelo aquecimento global.…”