Climate Change and Child Health Inequality: A Review of Reviews
Sustainable Development Goals: 3, 7, 12, 13, 16
- SDG 3 - Good Health and Well-Being
- SDG 7 - Affordable and Clean Energy
- SDG 12 - Responsible Consumption and Production
- SDG 13 - Climate Action
- SDG 16 - Peace, Justice and Strong Institutions
There is growing evidence on the observed and expected consequences of climate change on population health worldwide. There is limited understanding of its consequences for child health inequalities, between and within countries. To examine these consequences and categorize the state of knowledge in this area, we conducted a review of reviews indexed in five databases (Medline, Embase, Web of Science, PsycInfo, Sociological Abstracts). Reviews that reported the effect of climate change on child health inequalities between low- and high-income children, within or between countries (high- vs low–middle-income countries; HICs and LMICs), were included. Twenty-three reviews, published between 2007 and January 2021, were included for full-text analyses. Using thematic synthesis, we identified strong descriptive, but limited quantitative, evidence that climate change exacerbates child health inequalities. Explanatory mechanisms relating climate change to child health inequalities were proposed in some reviews; for example, children in LMICs are more susceptible to the consequences of climate change than children in HICs due to limited structural and economic resources. Geographic and intergenerational inequalities emerged as additional themes from the review. Further research with an equity focus should address the effects of climate change on adolescents/youth, mental health and inequalities within countries.
The uneven distribution of social and environmental factors on birth and early life give rise to avoidable child health inequalities . Differences in child survival, health, development and well-being are stark between low- and middle-income countries (LMICs) and high-income countries (HICs) . Many children in LMICs live in circumstances in which they are deprived of essential determinants of health such as clean air, adequate shelter, nutrition, safe water and sanitation , all of which contribute to the higher risk of adverse child health outcomes such as stunting secondary to malnutrition , acute respiratory illness , diarrheal disease  and vector-borne diseases such as malaria . Despite improvement in child survival rates within these countries, children from poorer households remain disproportionately vulnerable: on average, the risk of dying before age 5 is twice as high for children born into the poorest households as it is for those born into the richest . Inequalities within HICs exist as well with many children in low income households experiencing high levels of air pollution , food insecurity  and poor housing conditions .
Climate change is an ongoing urgent global problem. The recently published sixth assessment Intergovernmental Panel on Climate Change (IPCC)  asserts that anthropogenic greenhouse gas emissions have been responsible for an increase in yearly average temperatures across the world currently estimated at 1.2 C over pre-industrial temperature levels. Without mitigation, global temperature change will likely increase by 1.5 C by 2030 and may increase 4.8 C by 2100. Observable planetary changes due to climate change including glaciers melting, water levels rising, prolonged heat waves, floods, droughts and rainfall have accelerated in 2020–21 with uncontrolled wild fires in the west coast of North America, parts of Australia and southern Europe and unprecedented flooding in China and central Europe.
Global warming and its consequences are now accepted as a significant threat to global health and well-being, and children are known to be particularly vulnerable to its effects . In 2009, Lancet Commission on Climate Change determined that climate change is the biggest global health threat of the 21st century . The commission concluded that most health impacts will be adverse and will occur via direct exposures (e.g., heat waves, extreme weather events) but also by significantly impacting basic social determinants of health. The commission further identified certain populations as “vulnerable” to climate change such as the elderly, children, individuals with underlying health conditions and populations in LMICs. Focusing on children more specifically, a scoping review published after the end date of our search , identified the range of childhood conditions exacerbated by direct and indirect effects of climate change, for example, vector-, water- and food-borne infectious diseases and mental health problems.
We conducted a scoping review of published review articles with the aim of assessing the strength of evidence for the extent and mechanisms by which climate change and its consequences differentially impact children in social groups within countries and in poorer compared with richer countries and identify knowledge gaps. The main research questions of the review were: What is the current state of knowledge on the impact of climate change and its consequences on child health inequalities? What is the evidence that climate change exacerbates child health inequalities? Is the evidence reported in the reviews supported by quantitative data comparing the impact of climate change and its consequences on different social groups within countries and/or between countries? Are the mechanisms by which climate change and its consequences may exacerbate and/or generate child health inequalities addressed in the included reviews?
2. Materials and Methods
We conducted a scoping review, guided by the methodology outlined by Arksey and O’Malley , to examine the main research questions listed above. The population of interest is children aged 0–18 years, the key concepts are climate change and inequalities in child health and the contexts of interest are social groups within countries, low and middle-income countries (LMICs) compared to high-income countries (HICs) and geographical locations.
The scoping review approach was favored as it allows researchers to, “identify, retrieve and summarize literature relevant to a particular topic for the purpose of identifying the key concepts underpinning a research area and the main sources and types of evidence available”  ( p. 14). In recent years there have been advancements in the methodology  and a rapid increase in its application due to its wide range of uses . According to Arksey and O’Malley, two features of a scoping review contrast it from a systematic review. First, where systematic reviews have a well-defined question and may examine a the researcher to identify and map key concepts of an area, and may include various study designs. Second, unlike a systematic review, a scoping review does not include a quality assessment of the included studies. Arksey and O’Malley further suggest that scoping reviews may have one of two purposes, either to serve as a first step towards a subsequent systematic review or research project, or it may be conceived as a method in its own right, to identify key concepts or gaps in the existing evidence and define the main sources of evidence.
Building on the scoping review approach, we chose to scope reviews rather than primary literature. The ”review of reviews” approach is efficient when aiming to capture how a concept is described in the literature and to map out emerging themes, rather than relying on primary literature. Examples of applications are in the examination of loneliness and social isolation interventions for older adults  and mental health promotion interventions .
In partnership with the Karolinska Institute in Stockholm, we led a review of peer reviewed reviews indexed in five databases (Medline, Embase, Web of Science, PsycInfo, Proquest). The search was conducted from database start dates to 21 January 2021. Search terms used for all databases are shown in the supplementary files (Tables S1 and S2). We defined climate change in broad terms. Examples of search terms were “Climate Change”, “Greenhouse Effect”, “Hot Temperature”, “Natural disaster”, “Heat wave” and “Wildfire”. The population of interest was children and young people less than 18 years old which we defined according to the age definition of the UN Convention of the Child . We considered a range of health conditions, including physical ailments, infectious diseases and mental health conditions. Mental health was defined broadly with the inclusion of disorders as well as psychological consequences of climate change. We defined inequalities in relation to specific indicators such as socioeconomic status, income, wealth, poverty, ethnicity and indigenous status within and between countries. There were no limits on years of publication nor languages.
The inclusion and exclusion criteria are shown in Table 1.
Our search strategy retrieved 743 reviews, with 520 reviews after deduplication. Though not retrieved in the initial search, one additional review article was included for its relevance to the topic and objective. Title and abstract evaluations rendered 114 reviews eligible for full-text analysis. Papers for full text analysis were allocated to groups of two researchers, each to undertake review and reach consensus. Disagreements were resolved by whole group decision. Following this, 91 articles were excluded leaving 23 reviews that were included for synthesis. The results of the review process are presented as a PRISMA flow diagram in Figure 1. In addition, we followed the charting approach described by Arksey and O’Malley and Levac et al. to synthesize results and comment on emerging themes.