By Nitya Mohan-Khemka, Sv?t Lustig Vijay, KE Seetha Ram
For decades, climate change has been framed as an environmental and economic issue. Only recently has the international community begun to recognize that the climate crisis represents a health emergency, already resulting in fatalities and disabilities due to air pollution, infectious diseases, extreme weather events, malnutrition, and mental health issues.
“The threats to health from climate change are immediate and present […]. For too long, health has been a footnote in climate discussions,” stressed Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization, at COP28 on Health Day in December 2023 (Fletcher 2023). Health Day was the first of its kind since the Conference of the Parties (COP) meetings began in 1995. It marked a historic moment for health advocates, who have long warned that climate change will have devastating impacts on global health.
Fossil Fuels: A Dirty Killer
Sixty-five years ago, a young geochemist, Charles David Keeling, demonstrated from his observation station atop Hawaii’s Mauna Loa volcano how fossil fuels drive greenhouse gas emissions (UK Research and Innovation 2023). But it is only recently that the serious health implications of fossil fuels have come to light. Every year, the burning of fossil fuels kills 5 million people, particularly in the People’s Republic of China and India (Lelieveld et al. 2023).
“Much like we can’t address lung cancer without acknowledging the impact of tobacco, it’s undeniable that over 75% of greenhouse emissions stem from oil, coal, and gas, which not only harm our planet but pose a grave threat to human health,” emphasized Tedros in the weeks leading up to COP28.
Fossil fuels do not need to be burned to make humans sick. Every week, people ingest up to 5 grams of plastics, which are derived from fossil fuels (WWF 2019). Overall, the health costs of plastics exceed $250 billion a year (Landrigan et al. 2023).
Plastics contain thousands of health-harming chemicals and carcinogens that have been linked with stillbirth, low birth weight, childhood cancer, neurodevelopmental impairment, and lung disease, as well as impaired endocrine, cognitive, and reproductive functions (Centre for International Environmental Law 2019; Landrigan et al. 2023; UNEP 2023a).
Plastics also drive the spread of infectious diseases, particularly in densely populated settings where sanitation is poor. Plastic debris can clog water drainage and provide favorable breeding environments for pathogens like Zika, dengue, or malaria (Maquart, Froehlich, and Boyer 2022).
Extreme Temperatures: An Escalating Threat
The year 2023 was the hottest on record. Extreme temperatures, including abnormally hot and cold temperatures, kill 5 million people every year—over half of whom live in Asia (Zhao et al. 2021).
Among people over 65, heat-related deaths have soared by 85% in the past decade. Older people, as well as young children and people with underlying health conditions, are highly vulnerable to heat stress. Extreme heat is linked with heatstroke, disrupted sleep, acute kidney injury, poorer pregnancy outcomes, cardiovascular and respiratory complications, and adverse mental health outcomes (Romanello et al. 2023).
Extreme heat also restricts people’s capacity to exercise and work, further compromising their health and well-being (Daalen et al. 2022). The resulting loss in productivity is enormous, costing societies $863 billion a year (Romanello et al. 2023).
As the planet warms, extreme weather events like wildfires have become increasingly common, severe, and longer (Hondo 2023; WHO 2023a). Wildfires strain health systems, trigger accidents and injuries, and spread hazardous chemicals (Finlay et al. 2012; WHO 2023a; Xu et al. 2020).
Wildfire smoke is particularly toxic and can contain lead, aromatic hydrocarbons, nitrous oxide, and particulate matter (PM). PM2.5 is particularly dangerous as it is linked with premature death, cognitive impairment, and diseases of the lungs, brain, and heart (Finlay et al. 2012; WHO 2023a; Xu et al. 2020).
Infectious Diseases and Antimicrobial Resistance
The coronavirus disease (COVID-19) was not the first pandemic in human history, and evidently it won’t be the last. The threat of infectious diseases looms large with rising temperatures, urbanization, deforestation, the increased movement of people and goods, and increasingly frequent extreme weather events.
Warmer temperatures have made it easier for vectors like Aedes mosquitoes to spread diseases such as dengue (Romanello et al. 2022), and since 2000, dengue cases have grown by a factor of 10 (WHO 2023b). Asia currently bears 70% of dengue cases, but that may change as half of the world becomes vulnerable to the virus (WHO 2023b).
Climate change is also turbocharging antimicrobial resistance (AMR), complicating the treatment of even the most common infections. Every year, AMR kills 5 million people (Murray 2022). Extreme weather events, like floods, have accelerated the spread of AMR, since they create optimal conditions for it to spread, mainly by driving overcrowding and poor sanitation (UNEP 2023b).
As infectious diseases surge, they are likely to perpetuate malnutrition in a vicious cycle (Fanzo and Downs 2021). The burden of malnutrition is expected to rise further as climate change reduces the nutritional value of staple foods and depresses crop yields by up to 30% (Global Commission on Adaptation 2019; Ebi and Loladze 2019).
Moving from Declarations to Decisive Actions
Climate change presents an imminent and existential threat to global health. Fortunately, countries have access to a multitude of lifesaving and highly cost-effective options to quickly cut greenhouse gas emissions and safeguard citizens from the catastrophic health impacts of climate change (ADB 2011; Mohan-Khemka et al. 2024). These include mitigation measures, like the introduction of low-carbon medical products, the enforcement of carbon taxes, and strict air quality regulations, as well as a transition to renewable energy sources.
Adaptation strategies, meanwhile, can encompass the formulation of multisectoral national health adaptation plans, the capacity-building of relevant health professionals, and the enhancement of weather surveillance systems. However, the success of such ambitious initiatives relies on genuine international collaboration and innovative financing for climate-vulnerable countries to address the climate adaptation funding gap of $366 billion a year. Closing this enormous funding gap still remains a key challenge since COP28 and will surely be a crucial issue in future discussions.
