Health and climate change in the spotlight

In the wake of the 2023 Lancet Countdown on health and climate change, we explore the report’s key themes, and how publications in PLOS journals are helping to address knowledge gaps

In a year that looks set to be the hottest on record, the impacts of climate change are becoming increasingly severe and are being felt ever more widely. In this context, the 2023 Lancet Countdown on health and climate change, published on 14th November, provides vital insights into the complex interactions between climate change, health and health systems [1]. This edition of the annual report is the culmination of a major international effort by 114 authors from 52 institutions to assess the latest evidence and to identify opportunities to mitigate and adapt. Here we highlight some of the key themes emerging from the report and relate them to the evidence and arguments presented in a range of research, reviews and commentary recently published in PLOS journals.

One of the report’s starkest messages, based on projections developed in collaboration with the Climate Vulnerable Forum, is that, on the current warming trajectory, we should expect a three-fold increase in heat-related mortality by the mid 21st century. The effects of increasing temperatures on mortality are highlighted in work by Rippstein et al. published in PLOS Climate, which shows that more frequent ‘tropical nights’ (when the night-time minimum temperature remains above 20°C) are leading to increasing numbers of heat-related deaths in Swiss cities [2]. Extreme heat can have disproportionately strong impacts on demographic groups made vulnerable by their age, health status, or socioeconomic position. In a PLOS Climate Opinion article, Limaye has argued for intensified efforts to clarify the particular consequences of extreme heat for women in the Global South, in terms of health, wellbeing, and livelihoods [3]. Of course, extreme heat is not the only acute climate event that can lead to serious health impacts for individuals and populations; research by Yu et al. published this year in PLOS Medicine has shown that exposure to wildfire smoke could represent a large-scale and growing risk factor for cancer-related mortality [4].

The authors of the Lancet Countdown report draw attention to the fact that the health-related impacts of climate change, acute and chronic, are distributed unequally across the globe and within societies. Research by Schwarz et al., published in PLOS Global Public Health, has demonstrated that transboundary climate events can lead to contrasting public health outcomes depending on local social and economic conditions [5]. But inequities are not limited to climate impacts; the report is also clear that measures taken in support of climate change mitigation and energy transitions- whether in low- or high-income countries- do not always deliver benefits on an equitable basis. A study by Joseph et al., published in PLOS Climate, shows that this is true of certain health-related climate adaptation interventions at the local level in the United Kingdom [6].

As the authors of the Lancet Countdown report emphasise, climatic factors are key determinants of infectious disease epidemiology, including through their influence on pathogen and host biology and behaviour. Research by Van Wyk et al., published this year in PLOS Neglected Tropical Diseases and focusing on dengue and Zika, exemplifies the type of bioclimatic analyses and projections that are vital for decision-makers to understand and prepare for the likely changes in vector-borne disease epidemiology driven by climate change [7].  The effects of climate change on infectious disease epidemiology were discussed in depth in a PLOS Biology Collection published in 2020. Although often thought of in the shape of an abstract, simplified pathosystem, the interactions between pathogens and their hosts (human or otherwise) take place in a broader ecological context, which is itself modulated by climatic factors. The importance of taking a broader planetary health perspective is advocated by Wasan and Wasan in a Viewpoint published in PLOS Neglected Tropical Diseases, in which the authors explain how the effects of climate change on soil health can cascade through to increased risk of neglected tropical disease transmission [8].

The interlinkages between climate, health, water, food, and energy are central to the planetary health paradigm, and these connections are emphasised in the Lancet Countdown report. The potential for climate change effects, particularly extreme events, to have cascading impacts on interconnected societal sectors is highlighted by a PLOS Climate study by Niggli et al., which paints a picture of the complexities and contingencies inherent in climate adaptation pathways [9]. Intersectoral interconnections are not just pathways for risk propagation; they can also be routes for climate action, and the Lancet Countdown report speaks of the need to identify ‘transformative opportunities’ at the nexus of these domains. The case for seeking transformative solutions to the multisectoral ‘wicked problems’ facing society as a result of climate change is explored in an article by Deivanayagam and Osborne in PLOS Global Public Health [10]. Meanwhile, research by Taillie et al. published in PLOS Medicine provides an example of how intersectoral connections can allow interventions to achieve health and climate co-benefits. Their work shows how the importance of food systems as sources of greenhouse gas emissions means that behavioural interventions relating to dietary habits can contribute to climate change mitigation [11]. 

Being able to measure, understand, and enhance the resilience of healthcare systems to the effects of climate change is a major theme in the Lancet Countdown report. A number of recent PLOS journal articles have examined factors that affect the resilience of health systems in the face of climate shocks (e.g. Yglesias-González in PLOS ONE [12]), or explored opportunities for building systemic resilience through One Health approaches (e.g. Sekabira et al. in PLOS Sustainability & Transformation [13]). Beyond the higher level design of health systems, the preparedness and training of the healthcare workforce itself is a crucial factor in embedding climate resilience, and is the theme of a call to action by Sorensen et al. published in PLOS Climate [14].

Even if appropriate, evidence-based measures for increasing the climate resilience of health systems can be identified, the challenge of finding the resources to implement these measures can present an immediate stumbling block, especially in low-resource settings. A key message of the Lancet Countdown report is therefore the need for effective finance streams. This is very much a live topic in international climate negotiations, including at the upcoming UNFCCC COP28. Tracing and quantifying finance flows can be complicated, but a scoping review by Alcayna et al. recently published in PLOS Global Public Health brings together baseline data about the amount of adaptation finance currently reaching the health sector [15]. Scientific evidence can help guide effective finance programmes, including those designed to deliver co-benefits. In PLOS Water, O’Connell has argued that steps must be taken to create a more enabling environment to support finance flows towards interventions that jointly target climate resilience and improved water supply and sanitation [16]. 

Further research and action at the intersection of climate change and health is clearly of critical importance, including in a number of key areas identified in the Lancet Countdown report. The value of building a robust scientific evidence base motivated a call, recently published in PLOS Climate, for the convening of a comprehensive Global Burden of Climate Change study, akin to the Global Burden of Disease study [17]. Whether as part of such a coordinated international effort or through individual research projects, thousands of researchers around the world are contributing to our collective knowledge about climate and health, and making choices about how to share their findings. At PLOS we are committed to supporting the evaluation and dissemination of rigorous, ethical, and timely research- made accessible through our fully Open Access platform and Open Science options- that can be discovered and used by practitioners, policy- and decision-makers. Our newest journals- PLOS Mental Health and PLOS Complex Systems, now open for submissions- join our established titles in offering a home within their interdisciplinary remits for research covering crucial aspects of the climate-health nexus. PLOS Mental Health has a section dedicated to Environmental Impacts, whilst PLOS Complex Systems has sections focused on Climate & Natural Hazards and on Urban & Industrial Complexity. Right across our portfolio of journals, we are proud to work with global communities of authors, editors, and reviewers who share our mission of empowering global stakeholders to take effective action in the face of some of the greatest challenges of our time.

References

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