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Projeto de investigação
Assessment of the concurrence of heatwaves and droughts in Southeast Brazil under present and future climate change conditions: Impacts on public health
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Twenty-first-century demographic and social inequalities of heat-related deaths in Brazilian urban areas
Publication . Santos, Djacinto Monteiro dos; Libonati, Renata; Garcia, Beatriz N.; Geirinhas, João L.; Salvi, Barbara Bresani; Silva, Eliane Lima e; Rodrigues, Julia A.; Peres, Leonardo F.; Russo, Ana; Gracie, Renata; Gurgel, Helen; Trigo, Ricardo M.
Population exposure to heat waves (HWs) is increasing worldwide due to climate change,
significantly affecting society, including public health. Despite its significant vulnerabilities
and limited adaptation resources to rising temperatures, South America, particularly Brazil,
lacks research on the health impacts of temperature extremes, especially on the role played
by socioeconomic factors in the risk of heat-related illness. Here, we present a comprehen-
sive analysis of the effects of HWs on mortality rates in the 14 most populous urban areas,
comprising approximately 35% of the country’s population. Excess mortality during HWs
was estimated through the observed-to-expected ratio (O/E) for total deaths during the
events identified. Moreover, the interplay of intersectionality and vulnerability to heat consid-
ering demographics and socioeconomic heterogeneities, using gender, age, race, and edu-
cational level as proxies, as well as the leading causes of heat-related excess death, were
assessed. A significant increase in the frequency was observed from the 1970s (0–3 HWs
year-1) to the 2010s (3–11 HWs year-1), with higher tendencies in the northern, northeast-
ern, and central-western regions. Over the 2000–2018 period, 48,075 (40,448–55,279)
excessive deaths were attributed to the growing number of HWs (>20 times the number of
landslides-related deaths for the same period). Nevertheless, our event-based surveillance
analysis did not detect the HW-mortality nexus, reinforcing that extreme heat events are a
neglected disaster in Brazil. Among the leading causes of death, diseases of the circulatory
and respiratory systems and neoplasms were the most frequent. Critical regional differ-
ences were observed, which can be linked to the sharp North-South inequalities in terms of
socioeconomic and health indicators, such as life expectancy. Higher heat-related excess
mortality was observed for low-educational level people, blacks and browns, older adults, and females. Such findings highlight that the strengthening of primary health care combined
with reducing socioeconomic, racial, and gender inequalities represents a crucial step to
reducing heat-related deaths.
Compound drought and heatwaves over South America
Publication . Geirinhas, João; Russo, Ana; Santos, Renata Libonati dos; Gonzalez Miralles, Diego
Recent decades in South America (SA) have been marked by an increase in the frequency and magnitude of hot and dry spells. This changing pattern is unequivocally tied to an unsustainable level of anthropogenic greenhouse emissions. Future climate change projections indicate a further aggravation of this trend, representing a serious threat to ecosystem sustainability and to human well-being. Over the past few years, the scientific community has been joining efforts to improve the knowledge around this topic. Even so, a thorough characterization of droughts and heatwaves, particularly when their occur in a compound event manner, is still lacking for SA. The assessment, under a climate change context, of the atmospheric forcing mechanisms and of the land–atmosphere feedbacks that control the intensification and propagation of hot and dry spells, is still missing for the region.
This thesis aims to fill these gaps and to provide solid answers to the following main research questions: (i) What was the historical evolution of compound drought and heatwave (CDHW) conditions over SA? (ii) What are the physical mechanisms driving these compound events? (iii) What should we expect in a future climate change scenario?
Results show that vast areas in SA have recorded a significant increase in the number of CDHW episodes. Recent summer periods have witnessed strong soil moisture–temperature coupling conditions that triggered record-breaking temperatures and outstanding ‘mega-heatwave’ episodes. A long-term soil drying trend resulting from a joint contribution of natural variability, via large-scale tropical and subtropical dynamics, and climate change, via increasing temperatures, has predisposed some regions in SA to face unprecedented droughts, temperatures and devastating wildfires in the recent years. An overall increment of these compound episodes is expected in the future, partially due to an enhancement of the soil moisture–temperature coupling in some regions of SA. This thesis highlights the complex interplay between distinct physical mechanisms that modulate the occurrence of CDHW conditions, and calls attention to under-examined feedback processes that need to be properly addressed by climate models, setting ground for a more effective design of mitigation measures by authorities.
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Fundação para a Ciência e a Tecnologia
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Número da atribuição
2020.05198.BD