Climate change impacts on health in Aotearoa New Zealand: a scoping review

Anthropogenic climate change, mediated through environmental changes, poses significant direct and indirect challenges to human health—death, injury, disability, wellbeing, inequity and social connectedness—to the extent it has been characterised as a global health emergency for the last decade.^1—3 While every continent will be exposed to the adverse human health impacts of climate change (hereafter climate–health impacts), certain populations and regions are more vulnerable.² Vulnerability considers exposure, existing sensitivity and the capacity to prepare, respond or adapt.⁴

While the body of climate–health scholarship is growing in Aotearoa New Zealand, there is value in an updated comprehensive methodological review. The purpose of this paper is to review the evidence on the direct and indirect climate–health impacts in Aotearoa New Zealand. The aims are threefold. Firstly, investigate the range of evidence related to climate–health impacts, with particular attention to the climate processes of concern to health and who, where and what activities (e.g., occupations, tasks) are most vulnerable. Secondly, consolidate academic (published and peer-reviewed literature) and grey literature to expand the depth and breadth of the review. Lastly, identify gaps in the current literature to inform future research priorities and policy interventions that address the intersections of climate change and health in Aotearoa New Zealand. Together, these support the identification of intersectional vulnerabilities—networked, and not able to be attributed to a single event—and research gaps, which are critical for climate–health research because of the inequitable impact of climate change and the multifaceted response required.

These purposes contribute to building a conceptual overview of the interaction and processes related to changing climatic conditions, and the direct and indirect health impacts that result. The Helldén et al. conceptual framework—which we adapt to an Aotearoa New Zealand context in Figure 5—offers a structured way to visualise how processes influence health outcomes while highlighting vulnerable populations, geographic regions and activities and potential opportunities for mitigation and adaptation.⁵

Methods

This review was informed by Arksey and O’Malley’s five-stage scoping review methodology—suitable for broad research questions—to address the research question: what is the evidence regarding the impact of climate change on human health in Aotearoa New Zealand?⁶ It focusses on the climate change processes of concern to health, and who, where and what activities are most vulnerable.

A review protocol and search strategy—aligned to the PRISMA ScR checklist and registered with PROSPERO—assisted paper selection. The search strategy employed keywords (alongside their Boolean operators) (Table 1). These were developed with assistance from a discipline-specific University of Oxford librarian and were used to yield academic literature on 3 February 2024 in the following databases: Ovid Embase, Ovid Global Health, Ovid MEDLINE, Scopus and Web of Science (all databases), referenced in Appendix 1.

A wide interpretation of grey literature was adopted so that the review could include documents that are influenced by research but take an applied or policy focus.⁷ Electronic grey literature databases, customised Google searches and searching (Table 2) comprised the grey literature search strategy. The websites and databases were selected through a process of keyword searching and consultation with experts.

Although common inclusion and exclusion criteria were applied (Table 3), selection processes differed. Academic literature was uploaded to and stored in Rayyan.ai. Rayyan.ai detected potential duplicates, which were then resolved and screened manually by two independent reviewers. Reviewers independently screened titles and abstracts, progressing to full-text review when necessary. Disagreements were resolved by consensus and, if needed, with supervisor input. The searching processes were further iterated for Google searches. Relying on relevancy filters—embedded into Google searching—the first 60 results were screened. The same two independent reviewers assessed relevance, resolving conflicts before inclusion.

 The final step—backward and forward snowballing—was limited for grey literature due to the lack of comprehensive referencing within the selected papers themselves.⁸ Two additional papers were subsequently identified, screened and added to the review.^9,10 Information was extracted inductively—as they organically emerge—from the selected papers into a combined spreadsheet, and then organised into results tables (Appendix 2). Narrative synthesis—based on the identification of themes that emerge through the organisation of the data—was used to collate, summarise and report the results.

View Table 1–4, Figure 1–5.

Results

A total of 61 papers (n=61), were included in the final review, represented in Figure 1.

Climate change processes of concern to health

Most papers included in the review specified particular climate change processes of concern to health (Figure 2).

Climate change–induced health outcomes

The direct and indirect health burden of climate change in Aotearoa New Zealand is wide ranging, from physical and mental health to social connectedness and access to—and delivery of—healthcare. However, heat-related illnesses and death associated to temperature changes, and enteric diseases, including water- and food-borne diseases, are impacts of great concern to Aotearoa New Zealand, as is access to safe drinking water and food supplies as well as health system impacts and access to healthcare services. The distinction between direct and indirect health outcomes in climate–health literature is somewhat immaterial in this review because of the broad categorisation of health outcomes, and the multiple potentially overlapping and interacting climate change processes that give rise to such health impacts. We have instead chosen to map these health outcomes against the associated climate change processes (Table 4).

Climate–health outcomes by demographic group

A growing body of evidence in Aotearoa New Zealand suggests that ethnicity, age, skin colour, occupation, gender, housing and living conditions, disability and existing health needs and socio-economic deprivation affect vulnerability to climate–health impacts.

The impact of climate change on health for tangata whenua (people born of the land/Indigenous people) was widely addressed by many papers included in the review.^14,47,54,59 Three reasons were commonly acknowledged: firstly, the inseparable ancestral relationship of tangata Māori with Te taiao (the environment), including whenua (land) and wai (water);^{10,14,21,23,24,52,60} secondly, the existing inequitable burden of diseases and illness;^{9,10,15,21,23,26,27,30,41,52,59,61} and lastly, disproportionate socio-economic deprivation.^{12,14,15,19,21,23,26,27,52,59} Similar reasons were cited for the susceptibility of Pacific peoples in Aotearoa New Zealand.^{10,12,30,52,61,62}

While there is growing concern that children experience greater anxiety due to climate change,^{10,15,23,44,55,61} McBride et al.’s research states that there is no statistically significant evidence to support the view that psychological harm from climate concern is stronger in young people in Aotearoa New Zealand.⁶³ However, children are vulnerable to enteric and heat-related diseases and mortality due to immature thermoregulation.^{15,17,18,32,51} At the other end of life, older adults are also identified as one of the key vulnerable groups in Aotearoa New Zealand due to heat-related illnesses and death.^{9,15,16,25,38,51}

Pregnant women are vulnerable to rising temperatures.^15,17,18 During extreme weather or heat stress, disabled people and those with health needs reliant on life-support equipment may face limited support, communication and evacuation.^{10,12,15,16,55} Specific health conditions including “kidney diseases, diabetes, heart conditions, respiratory insufficiency, Parkinson’s disease, cancer and severe mental illness”^17,18 and chronic cardio-respiratory conditions were specifically identified.⁵²

Socio-economic deprivation sits at the nexus of other demographic indicators of vulnerability that have been summarised in the review, including housing and living conditions, ethnicity and gender. Papers describe poverty as a cause of vulnerability in the face of climate–health impacts^{9,19,26,27,52} and, equally, housing insecurity.^{12,16–18,37,42,52}

Climate–health outcomes by geographic region

Coastal regions, large metropolitical areas, rural areas and regions experiencing disproportionate socio-economic inequity in Aotearoa New Zealand experience distinct climate–health impacts. Together, these regions encompass the majority of Aotearoa New Zealand (Figure 3). Coastal and flood-prone areas are vulnerable to sea-level rise and coastal inundation.^{9,15,17,18,52} Six papers identified rural and remote farming communities as vulnerable to climate change.^{9,10,19,23,52,61} Their sensitivity to extreme weather disrupts farming, social cohesion and income, impacting mental health.^19,23,61 Four papers highlighted risks for those relying on untreated or high-risk water supplies due to changes in water-borne diseases.^12,22,29,64 Large metropolitan areas—Christchurch and Auckland—already experience heat-related deaths, with 14 fatalities per year among adults over 65 when temperatures exceed 20 degrees Celsius.³⁸

The review surfaced the complex interplay of existing geographic susceptibility with demographic characteristics of communities that can exacerbate existing vulnerability. Northland^{12,16,17,23,34,37} and Tairāwhiti^{10,16,17,22,32,34,37} are susceptible to extreme weather events and temperature rise, alongside existing health, social and economic vulnerability. Despite their size differences, the median personal income of adults in Tairāwhiti (NZ$35,800), similarly to Northland (NZ$33,100), is markedly lower than the national median (NZ$41,500).⁶⁵ Both regions have significant Māori populations relative to size (54% and 37% in Tairāwhiti and Northland respectively). They are also regions with higher levels of vulnerable mobile populations and persisting health inequities.^37,66

Climate–health outcomes by activity

The vulnerability of occupational and recreational activities was the least evidenced part of this review. Nonetheless, it underscores the significance of climate change for occupational health, which was the focus of three papers in the review.^28,49,52 Figure 4 presents a range of industry-related activities that are vulnerable to climate–health impacts.

Many of these industries are based outdoors, where workers are exposed to heat stress, air pollution and sun damage.^12,15,22 Farmers are vulnerable to stress and poor mental health mediated through impacts to stock health following severe weather events.⁵² Healthcare workers and first responders are susceptible to stress, burnout, abuse and poor occupational environments through response efforts.¹⁰ Overall, this review reveals a critical research gap in our understanding of the structural conditions shaping occupational exposure and risk.

Discussion

Drawing on the Helldén et al. framework, this scoping review provides a contextual adaptation to the Aotearoa New Zealand context (Figure 5).⁵

This review did not prescribe a definition of health, allowing it to be interpreted from multiple perspectives. As identified, these ranged from disease, injury and mortality to a spectrum of mental health impacts. Health was also understood spiritually, shaped by ancestral ties to whenua—such as the inability to return for tangihanga (funerals) or burials at urupā (cemeteries)—disrupted by climate-induced extreme weather.^10,19,47 Furthermore, health was also framed defined by economic and social determinants: forced displacement, food, water and housing insecurity and impact to social networks, cohesion and inequity. These social and economic determinants of health were portrayed as core elements of health in their own right^15,34,55,57 and as prerequisites, causes or symptoms of mental or physical health.^14,67 In this sense, health was commonly described collectively, with reference to public infrastructure, facilities, community belonging¹⁵ and social cohesion.^55,57 Health was also qualified by inequity^15,24 and through violence and conflict.^15,21,34,58 These findings show that climate change creates complex pressures that disproportionately affect marginalised groups. Furthermore, the impacts of climate change on physical and mental health are potentially exacerbated by community-level impacts of climate stressors.⁶⁸

Overwhelmingly, the papers in the review identified the harm of climate–health impacts. Few papers identified that there could be positive impacts arising from climate change. Examples include a reduction in cold temperatures, which could see a reduction in influenza and winter illness; reduced food insecurity, allowing crops to grow in previously unsuitable conditions; and warmer temperatures encouraging greater physical activity.^15,16,47 However, there is no existing quantifiable evidence in Aotearoa New Zealand to support these claims, so further work is needed to understand how these potential benefits can be measured and realised to support action on climate change and eliminating health inequities.

As presented in Table 4, the review also highlighted how direct and indirect health outcomes are impacted by a multiplicity of climate change processes. For example, vector-borne diseases, including dengue, Ross River virus and P. falciparum malaria are associated with changing temperatures, sea-level rise, extreme weather events and extreme precipitation to name a few. Although such vectors are not currently endemic in Aotearoa New Zealand, the review identified that changing climatic conditions could mean these vectors become domestically established.

One benefit of this form of review is that it highlights connection and overlap between discrete parts of the literature. For example, by reviewing the literature firstly by climate change processes, then activity, geography and demography, we can begin to see the intersectionality of the evidence relating to climate–health impacts in Aotearoa New Zealand. Rooted in critical and feminist theoretical traditions, intersectionality values understanding embedded social structures and power.⁶⁹ It emphasises that vulnerability is not attributable to a single cause, but a network of interconnecting and dynamic considerations.⁶⁹ Through this perspective we can begin to expose the connection and power relationships underpinning the vulnerabilities that this review has surfaced. This is important because—as this review demonstrates—climate change comprises many different, albeit connected, processes and events that threaten all aspects of health, including compounding health and relating inequities that already exist.⁵⁹

This review has some limitations. Overall, the literature reviewed is fairly limited, with significant gaps. Papers varied substantially in their methodologies and protocol—including some grey literature reports that did not provide a protocol—which increases the heterogeneity of the review. This lack of uniformity required a more interpretive approach to synthesising the findings. The review did not consider articles that were not available online. This would have considerably changed the scope and search strategy of the review, likely requiring a larger team of contributors. While the use of Rayyan.ai in this review gives rise to the potential for significant limitations in the rigor of the review, the software was simply used by multiple reviewers to store and manually sort the papers that were extracted from academic databases.

The exclusion of Intergovernmental Panel on Climate Change or similar organisational reports because of their lack of national specificity could be interpreted as a limitation of this review; however, the findings of this review are consistent with them and do not raise additional novel substantive content. Similarly, the decision to use only the term “climate change” when searching grey literature, rather than incorporating alternative terms commonly used in academic literature, may have limited the scope of the material identified. However, this choice was made for pragmatic reasons due to the limited search functionalities of grey literature platforms.

The review also excluded adaptations or solutions to climate–health impacts. Considered in isolation, this review runs the risk of deficit framing, which has the potential to entrench and recirculate negative and disempowering perspectives of vulnerability within marginalised communities. The absence of quality or risk of bias assessment(s) in scoping reviews gives rise to the potential for a degree of uncertainty in the accuracy of the evidence synthesised. While Pourzand et al. have successfully scoped adaptation policy in Aotearoa New Zealand related to climate change and health, a review that comprehensively summarises impacts and solutions would be of great benefit.⁷⁰ Equally, narrowing a review to focus on demographic characteristics—ethnicity, gender and age—would be helpful to understand the nuance within climate-vulnerable groups in Aotearoa New Zealand.

Undeniably, attribution—linking climatic events to climate change, and in turn to associated health impacts—is one of the most significant challenges of this research field, as well as policy, economic and social responses. The challenge of attribution does not refute the unequivocal determination that climate change is anthropogenic, nor the need for concerted action, but it does influence—made apparent through this review—the type and distribution of the research that has been conducted into climate–health impacts to date, including the critical research gap in the area of climate change impacts to occupational health in Aotearoa New Zealand.

Conclusion

This review contributes to the existing literature on the impact of climate change on health in Aotearoa New Zealand and summarises the climate change–induced health outcomes relevant to Aotearoa New Zealand, focussing on who and where is affected and what activities are at risk. While there is an expanding body of international evidence on climate change and health, the 61 papers addressing this nexus in Aotearoa New Zealand since 2001—of which 35 are grey literature—highlight growing national concern for this issue. Understanding the specificities of the Aotearoa New Zealand context is crucial to ensuring that responses to climate change–induced health impacts are responsive to intersectionality, complexity, structural drivers and lived experience, as this review has revealed.

Notes

The term Aotearoa New Zealand is used throughout this paper, and in the search terms of this review. Aotearoa is the Indigenous, Māori term for New Zealand. Written together as Aotearoa New Zealand it refers to the contemporary nation.

View Appendix 1, Appendix 2.