Abstract
SummaryBackgroundThe global literature on the links between climate change and human health is large, increasing exponentially, and it is no longer feasible to collate and synthesise using traditional systematic evidence mapping approaches. We aimed to use machine learning methods to systematically synthesise an evidence base on climate change and human health.MethodsWe used supervised machine learning and other natural language processing methods (topic modelling and geoparsing) to systematically identify and map the scientific literature on climate change and health published between Jan 1, 2013, and April 9, 2020. Only literature indexed in English were included. We searched Web of Science Core Collection, Scopus, and PubMed using title, abstract, and keywords only. We searched for papers including both a health component and an explicit mention of either climate change, climate variability, or climate change-relevant weather phenomena. We classified relevant publications according to the fields of climate research, climate drivers, health impact, date, and geography. We used supervised and unsupervised machine learning to identify and classify relevant articles in the field of climate and health, with outputs including evidence heat maps, geographical maps, and narrative synthesis of trends in climate health-related publications. We included empirical literature of any study design that reported on health pathways associated with climate impacts, mitigation, or adaptation.FindingsWe predict that there are 15 963 studies in the field of climate and health published between 2013 and 2019. Climate health literature is dominated by impact studies, with mitigation and adaptation responses and their co-benefits and co-risks remaining niche topics. Air quality and heat stress are the most frequently studied exposures, with all-cause mortality and infectious disease incidence being the most frequently studied health outcomes. Seasonality, extreme weather events, heat, and weather variability are the most frequently studied climate-related hazards. We found major gaps in evidence on climate health research for mental health, undernutrition, and maternal and child health. Geographically, the evidence base is dominated by studies from high-income countries and China, with scant evidence from low-income counties, which often suffer most from the health consequences of climate change.InterpretationOur findings show the importance and feasibility of using automated machine learning to comprehensively map the science on climate change and human health in the age of big literature. These can provide key inputs into global climate and health assessments. The scant evidence on climate change response options is concerning and could significantly hamper the design of evidence-based pathways to reduce the effects on health of climate change. In the post-2015 Paris Agreement era of climate solutions, we believe much more attention should be given to climate adaptation and mitigation options and their effects on human health.FundingForeign, Commonwealth & Development Office.
Highlights
The effects of climate change on health are already evident in populations worldwide and threaten to undermine the past 50 years of global gains in public health.1 Health can be affected by the changing climate through many causal pathways, including the direct effects of heat and extreme weather events,2–4 ecosystemmediated effects and effects mediated by socioeconomic pathways, such as increased poverty, population displacement, and conflict.11,12 Climate change is expected to weaken coping strategies, especially among poor communities in low-income countries.3,13,14Identification of the most crucial links between climate change and health to enable mitigation and adaptation responses that support health is underpinned by timely and regularly updated review of the scientific evidence base.15–17 Two factors constrain the availability of such evidence reviews
Climate-health literature is dominated by impact studies, with only a minority of studies focusing on solutions and co-benefits. 13 380 (84%) of 15 963 available studies scored highest on the topic of impacts of CCVW on human health
We found that few studies focused substantively on the benefits to climate change mitigation or adaptation in the health sector
Summary
The effects of climate change on health are already evident in populations worldwide and threaten to undermine the past 50 years of global gains in public health. Health can be affected by the changing climate through many causal pathways, including the direct effects of heat and extreme weather events, ecosystemmediated effects (including through food systems and the distribution of vectors that transmit diseases such as dengue or malaria9,10) and effects mediated by socioeconomic pathways, such as increased poverty, population displacement, and conflict. Climate change is expected to weaken coping strategies (eg, mental health capacity, livelihood diversification, use of emergency assets, water conservation, and crop rotation), especially among poor communities in low-income countries.3,13,14Identification of the most crucial links between climate change and health to enable mitigation and adaptation responses that support health is underpinned by timely and regularly updated review of the scientific evidence base. Two factors constrain the availability of such evidence reviews. The effects of climate change on health are already evident in populations worldwide and threaten to undermine the past 50 years of global gains in public health.. Health can be affected by the changing climate through many causal pathways, including the direct effects of heat and extreme weather events, ecosystemmediated effects (including through food systems and the distribution of vectors that transmit diseases such as dengue or malaria9,10) and effects mediated by socioeconomic pathways, such as increased poverty, population displacement, and conflict.. Climate change is expected to weaken coping strategies (eg, mental health capacity, livelihood diversification, use of emergency assets, water conservation, and crop rotation), especially among poor communities in low-income countries.. Identification of the most crucial links between climate change and health to enable mitigation and adaptation responses that support health is underpinned by timely and regularly updated review of the scientific evidence base.. Research on climate and health takes place across various disciplines and silos, www.thelancet.com/planetary-health Vol 5 August 2021
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