Editing IPCC:AR6/WGII/Chapter-7 (section)

==== 7.1.7.2 Differential Vulnerability and Cascading Effects ====

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Vulnerability to climate change varies across time and location, across communities, and among individuals within communities; it reflects variations and changes in macro-scale non-climatic factors (such as changes in population, economic development, education, infrastructure, behaviour, technology and ecosystems) and individual- or household-specific characteristics, such as age, socioeconomic status, access to livelihood assets, pre-existing health conditions and ability (US Global Change Research Program, 2016; Chapter 1).

Many direct and indirect effects of climate change pose multiple threats to human health and well-being and can occur simultaneously, resulting in compounding or cascading impacts for vulnerable populations. For example, many of the long-term impacts of climate change on NCDs and injury described in Sections 7.2 and 7.3 are associated with future increases in air temperature and levels of air pollution; in many regions, and especially in large urban centres in Asia and Africa, these particular hazards are already causing substantial increases in morbidity and mortality due to respiratory illnesses ( [[#Tong--2016|Tong et al., 2016]] ). Climate change can therefore be expected to magnify such health risks over the long term.

At the same time, urban populations will also be experiencing indirect risks through climate change impacts on food and potable water systems, variations in the distribution and seasonality of infectious diseases and growing demand for shelter due to increased in-migration. The accumulation of these risks over time can be expected to generate accelerating declines in community resilience and health, with future vulnerability potentially expanding in a nonlinear fashion ( [[#Dilling--2017|Dilling et al., 2017]] ; [[#Liang--2017|Liang and Gong, 2017]] ; [[#El-Zein--2017|El-Zein and Tonmoy, 2017]] ; see also Chapter 6). Further, although each individual risk in isolation may be transitory or temporary for the individuals or groups exposed, taken cumulatively, the impacts could create conditions of chronic lack of well-being, and early life experiences with specific illnesses and conditions could have lifelong consequences ( [[#Watts--2015|Watts et al., 2015]] ; [[#Otto--2017|Otto et al., 2017]] ; WHO, 2018a). In this context, there is a distinct need for greater longitudinal research on vulnerability to multiple climatic and non-climatic health and well-being hazards over time ( [[#Fawcett--2017|Fawcett et al., 2017]] ). There is also need for more research to identify critical thresholds in social vulnerability to climate change ( [[#Otto--2017|Otto et al., 2017]] ); these include rapid, stepwise changes in vulnerability that emerge from changes in exposure (for example, air temperatures above which mortality rates or impacts on pre-natal health accelerate ( [[#Arroyo--2016|Arroyo et al., 2016]] ; [[#Ngo--2016|Ngo and Horton, 2016]] ; [[#Abiona--2017|Abiona, 2017]] ; [[#Auger--2017|Auger et al., 2017]] ; [[#Molina--2017|Molina and Saldarriaga, 2017]] ; [[#Zhang--2017b|Zhang et al., 2017b]] )) and thresholds in adaptation processes (such as when rural out-migration rates grow due to climate-related crop failures ( [[#McLeman--2017|McLeman, 2017]] )).

In virtually all of the research identifying particular climate-related risks to health, well-being, migration and conflict, specific types of individuals are identified as having higher levels of vulnerability and exposure to climate-related health hazards: people who are impoverished, undernourished, struggle with chronic or repeated illnesses, live in insecure housing in polluted or heavily degraded environments, work in unsafe conditions, are disabled, have limited education and/or have poor access to health and social infrastructure (WHO, 2018a). Their disproportionate exposure to ongoing climate hazards and their inability to recover from extreme events increase not only their own vulnerability but also that of the wider communities in which they live (US Global Change Research Program, 2016). Highly vulnerable populations are not evenly distributed across regions (Figure 7.2) nor within countries. Yet, even those fortunate enough to live in better neighbourhoods with greater financial means, higher-paying jobs and good access to resources and services, may experience adverse climate-related outcomes through community-level interactions and linkages (Haines and [[#Ebi--2019|Ebi, 2019]] ). Increased inequity itself threatens well-being and an effective response to climate change should not only avoid increased inequity but identify ways in which to reduce existing inequity.

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'''Figure 7.2 |''' '''Global distribution of vulnerable people from two indices, with examples (see also Technical Summary, this report).'''

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