Heat wave exposure in India in current, 1.5 °C, and 2.0 °C worlds

Mishra, Vimal; Mukherjee, Sourav; Kumar, Rohini; Stone, Dáithí A.

doi:10.1088/1748-9326/aa9388

Cited by 133 publications

(114 citation statements)

References 45 publications

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“…The few existing studies that performed similar analysis found that a shift from a high to a low radiative forcing pathway led to greater reduction in exposure than a shift from a high to a low population growth pathway. This holds true at the global scale (Jones et al, ) but also (i) in the United States, where Jones et al () found that a shift to a lower emission pathway or to a lower population growth pathway would reduce exposure by ~56% and ~45%, respectively; (ii) in India, where Mishra et al () showed that a shift from high to low population growth has a lower influence on exposure than a shift from +2 to +1.5 °C; (iii) in Eastern Africa, where Harrington and Otto () found that shifting from +2 to +1.5 °C would reduce exposure by ~81%, whereas shifting from a medium (SSP2) to low (SSP1) population growth pathway would reduce exposure by ~28%; and (iv) in North Africa/Middle East and Sub‐Saharan Africa, where Jones et al () demonstrated that a shift from a high (SSP3) to low (SSP5) population growth pathway would lead to a lesser reduction in exposure than a shift from a high (RCP8.5) to low (RCP4.5) emission pathway (~33–39% vs. ~47–57%). Our results—while not entirely comparable because based on different population projections, HI, and scenarios range—differ slightly from those found in the literature in that a shift from a high to a low urban population growth pathway leads to a slightly greater reduction in exposure than a shift from a high to a low emission pathway (~51% vs ~48%).…”

Section: Discussionmentioning

confidence: 96%

Projections of Human Exposure to Dangerous Heat in African Cities Under Multiple Socioeconomic and Climate Scenarios

et al. 2019

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Human exposure to dangerous heat, driven by climatic and demographic changes, is increasing worldwide. Being located in hot regions and showing high rates of urban population growth, African cities appear particularly likely to face significantly increased exposure to dangerous heat in the coming decades. We combined projections of urban population under five socioeconomic scenarios—shared socioeconomic pathways—with projections of apparent temperature under three representative concentration pathways in order to explore future exposure to dangerous heat across 173 large African cities. Employing multiple shared socioeconomic pathway and representative concentration pathway combinations, we demonstrated that the aggregate exposure in African cities will increase by a multiple of 20–52, reaching 86–217 billion person‐days per year by the 2090s, depending on the scenario. The most exposed cities are located in Western and Central Africa, although several Eastern African cities showed an increase of more than 2,000 times the current level by the 2090s, due to the emergence of dangerous heat conditions combined with steady urban population growth. In most cases, we found future exposure to be predominantly driven by changes in population alone or by concurrent changes in climate and population, with the influence of changes in climate alone being minimal. We also demonstrated that shifting from a high to a low urban population growth pathway leads to a slightly greater reduction in aggregate exposure than shifting from a high to a low emissions pathway (51% vs. 48%). This emphasizes the critical role that socioeconomic development plays in shaping heat‐related health challenges in African cities.

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Section: Discussionmentioning

confidence: 96%

Projections of Human Exposure to Dangerous Heat in African Cities Under Multiple Socioeconomic and Climate Scenarios

et al. 2019

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“…Recognising that more-frequent and more-intense climate extremes will often lead to substantially higher impacts when they occur in highly populated areas, recent research has focused on the implications of future changes to heat extremes for specific regions of interest (Im et al 2017, Mishra et al 2017, Russo et al 2017, Jones et al 2015, Pal and Eltahir 2016. However, multiple lines of evidence also demonstrate that different regions of the world can experience substantially different rates of emergent climate change given the same amount of global mean warming (Mahlstein et al 2011, Diffenbaugh and Scherer 2011, Hawkins and Sutton 2012, Harrington et al 2016, Diffenbaugh and Charland 2016, Davis and Diffenbaugh 2016, Herold et al 2017, Frame et al 2017, Harrington et al 2017, Mora et al 2017.…”

Section: Introductionmentioning

confidence: 99%

Changing population dynamics and uneven temperature emergence combine to exacerbate regional exposure to heat extremes under 1.5 °C and 2 °C of warming

Harrington

Otto

2018

Environ. Res. Lett.

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Understanding how continuing increases in global mean temperature will exacerbate societal exposure to extreme weather events is a question of profound importance. However, determining population exposure to the impacts of heat extremes at 1.5 • C and 2 • C of global mean warming requires not only (1) a robust understanding of the physical climate system response, but also consideration of (2) projected changes to overall population size, as well as (3) changes to where people will live in the future. This analysis introduces a new framework, adapted from studies of probabilistic event attribution, to disentangle the relative importance of regional climate emergence and changing population dynamics in the exposure to future heat extremes across multiple densely populated regions in Southern Asia and Eastern Africa (SAEA). Our results reveal that, when population is kept at 2015 levels, exposure to heat considered severe in the present decade across SAEA will increase by a factor of 4.1 (2.4-9.6) and 15.8 (5.0-135) under a 1.5 • -and 2.0 • -warmer world, respectively. Furthermore, projected population changes by the end of the century under an SSP1 and SSP2 scenario can further exacerbate these changes by a factor of 1.2 (1.0-1.3) and 1.5 (1.3-1.7), respectively. However, a large fraction of this additional risk increase is not related to absolute increases in population, but instead attributed to changes in which regions exhibit continued population growth into the future. Further, this added impact of population redistribution will be twice as significant after 2.0 • C of warming, relative to stabilisation at 1.5 • C, due to the non-linearity of increases in heat exposure. Irrespective of the population scenario considered, continued African population expansion will place more people in locations where emergent changes to future heat extremes are exceptionally severe.

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“…A large body of literature has suggested that future GHG increases will very likely enhance the duration, intensity, and frequency of heat extremes across the world (Jones et al, 2015;Lau & Nath, 2014;Meehl & Tebaldi, 2004;Mishra et al, 2017;Mora et al, 2017;Russo et al, 2014;Schär, 2016;Schoetter et al, 2015). However, very little attention has been devoted to contrasting the roles of future GHG increases and aerosol reductions in future heatwave characteristic projections.…”

Section: Discussionmentioning

confidence: 99%

Strong Influence of Aerosol Reductions on Future Heatwaves

Zhao

Bollasina

Stevenson

2019

Geophysical Research Letters

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Using the Community Earth System Model Large Ensemble experiments, we investigate future heatwaves under the Representative Concentration Pathway 8.5 scenario, separating the relative roles of greenhouse gas increases and aerosol reductions. We show that there will be more severe heatwaves (in terms of intensity, duration, and frequency) due to mean warming, with minor contributions from future temperature variability changes. While these changes come primarily from greenhouse gas increases, aerosol reductions contribute significantly over the Northern Hemisphere. Furthermore, per degree of global warming, aerosol reductions induce a significantly stronger response in heatwave metrics relative to greenhouse gas increases. The stronger response to aerosols is associated with aerosol‐cloud interactions, which are still poorly understood and constrained in current climate models. This suggests that there may exist large uncertainties in future heatwave projections, highlighting the critical significance of reducing uncertainties in aerosol‐cloud interactions for reliable projection of climate extremes and effective risk management.

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Heat wave exposure in India in current, 1.5 °C, and 2.0 °C worlds

Cited by 133 publications

References 45 publications

Projections of Human Exposure to Dangerous Heat in African Cities Under Multiple Socioeconomic and Climate Scenarios

Projections of Human Exposure to Dangerous Heat in African Cities Under Multiple Socioeconomic and Climate Scenarios

Changing population dynamics and uneven temperature emergence combine to exacerbate regional exposure to heat extremes under 1.5 °C and 2 °C of warming

Strong Influence of Aerosol Reductions on Future Heatwaves

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