Climate change and health: An impending crisis and a public health challenge

“Climate change is the greatest health challenge of the 21st century, but it is also our greatest opportunity to build a cleaner, healthier world.”

María Neira, World Health Organization

Climate change is a reality

There is overwhelming scientific evidence from various fields of study, including atmospheric science, oceanography, glaciology, and paleoclimatology, that the Earth's climate has undergone significant changes over the past century. These changes can largely be attributed directly or indirectly to human activities that have increased the concentration of greenhouse gases in the atmosphere. The Earth's surface temperature has increased by approximately 1.1 °C since the late 1800s, with the most substantial warming occurring in the last few decades.¹ As a result of this global warming, the Earth's oceans have experienced thermal expansion leading to melting of arctic ice and rise in sea levels. Over the last decade, there have been increased frequency and intensity of extreme weather events, such as heatwaves, droughts, floods, and hurricanes. Overall, the climate change is not only affecting humans but also causing shifts in the distribution and behaviour of many plant and animal species leading to a disruption of ecosystems and threatening biodiversity.^2,3

Threat of climate change to health is unequivocal

The World Health Organization (WHO) has emphasized that climate change represents the most severe threat to essential human needs that are critical for good health. It compromises access to clean air by increasing levels of air pollutants and exacerbating respiratory illnesses.⁴ Safe drinking water sources are endangered due to droughts, floods, and contamination. Food security is jeopardized as changing temperatures and precipitation patterns disrupt agricultural yields, leading to malnutrition and undernutrition. Warmer conditions can also facilitate the proliferation of water-borne and food-borne illnesses.⁵ It introduces new challenges in controlling and preventing the spread of infectious diseases. Changing temperature and precipitation patterns alter the geographical distribution and prevalence of vector-borne diseases exposing host populations to longer and intense transmission seasons. The effect of climate change on mental health is a significant but often overlooked aspect of its overall burden on humanity. It takes many forms, including climate anxiety and eco-grief resulting from witnessing environmental degradation, as well as trauma and post traumatic stress disorder (PTSD) resulting from extreme weather disasters. Furthermore, proper shelter is also at risk as extreme weather events like storms and floods damage infrastructure and displace populations.⁶ Environmental degradation, resource scarcity, and economic disruptions caused by climate change can undermine access to healthcare, disrupt public health systems, and exacerbate existing health disparities.

The most vulnerable are the ones most affected by climate change

Climate change disproportionately affects the most vulnerable populations and underdeveloped nations, exacerbating existing inequalities and posing significant challenges to their health and well-being. The Global Climate Risk Index for 2021, based on data from 2000 to 2019, affirms that underdeveloped nations experience greater impact compared to developed ones and raises concerns regarding existing vulnerabilities in areas where climate change may escalate the frequency or intensity of extreme events.⁷ Developing countries lack the financial resources, infrastructure, and technical capacity to adapt to climate change. This prevents them from implementing measures to mitigate health risks, such as improving water and sanitation, early warning systems and health infrastructure.⁸ In addition, underdeveloped regions are often dependent on climate-sensitive sectors such as agriculture, fisheries and tourism, which can be severely disrupted by climate change-related events, leading to food insecurity, and economic instability. Poverty, poor living conditions, and limited access to health care are widespread, and the health impacts of climate change may overwhelm these already strained systems, making it difficult to sustain life and hamper the provision of effective prevention and treatment services in these resource-poor settings.⁹ In addition, extreme climate change is expected to result in the displacement of millions of people, disrupting social networks, increasing poverty and contributing to the spread of infectious diseases, particularly in overcrowded refugee camps or informal settlements.¹⁰

Healthcare professionals as advocates for climate solutions

Healthcare professionals, as responsible members of the community, have a unique opportunity to educate and advocate for measures that mitigate the impacts of climate change. Their credibility as caregivers lends significant weight to their voices on matters of public health and safety. By using simple, repeated messaging, they can reframe climate change from an abstract future issue to a tangible local problem that threatens public health. This approach allows individuals to perceive climate action as a means of protecting themselves and their loved ones, thereby reducing apathy. Healthcare professionals can inspire communities by highlighting the health benefits of sustainable practices and sharing relatable anecdotes that resonate on a personal level. It is important for healthcare professionals to play a crucial role in catalysing climate action at multiple levels through their diverse interactions across all demographics. Nurses can educate patients, doctors can lobby policymakers, administrators can green healthcare facilities, and researchers can advance solutions.¹¹ By leveraging their expertise, communication skills, and varied access points, healthcare professionals can become influential champions driving substantive climate policies and sustainability practices.

Adapting public health systems to climate change vulnerability

Climate change's detrimental health impacts are inequitably distributed, with vulnerable populations and regions bearing a disproportionate burden. The future health risks and strains on health systems will depend on the scale and the timing of adaptation investments and greenhouse gas emissions mitigation. Effective adaptation involves developing, implementing, evaluating, and continually modifying interventions that are responsive to changing climatic and societal conditions, with capacity for rapidly scaling up effective measures.¹² Public health plays a pivotal role in safeguarding against climate impacts by preventing emissions and building resilience, as well as providing care for those affected. These actions cover a wide range of strategies, including educational initiatives to train the general public and healthcare professionals to handle climate-related health emergencies, technical solutions that integrate climate considerations into sectors such as urban planning and vector control, legislative emissions regulations, enhanced surveillance and monitoring systems, and the establishment of robust health information systems to ensure efficient service delivery and financing across sectors. Individual-level adaptations include using personal protective measures to prevent vector-borne diseases and maintaining adequate hydration in hot weather conditions.¹³ In order to optimally address and build comprehensive resilience towards multidimensional challenges posed by climate change, it is inadequate to rely solely on siloed approaches within the health sector. It is crucial to prioritize cross-cutting investment in areas such as water management, energy provision, agricultural practices, and other climate-sensitive domains, in addition to bolstering core health system capabilities.

Small steps to greater success

Climate change and its impact on health is a highly complex issue with far-reaching consequences, necessitating comprehensive, large-scale efforts and intersectoral interventions. As the famous Chinese proverb goes “The journey of a thousand miles begins with a single step”. India has demonstrated notable foresight and commitment in addressing the health impacts of climate change through the National Action Plan on Climate Change and Human Health (NAPCCHH). The NAPCCHH conceived under the Prime Minister's Council on Climate Change in 2015 and revised in 2021, serves as a comprehensive framework to mainstream climate change adaptation and mitigation into the country's public health infrastructure. The action plan outlines strategic priorities, including strengthening health system preparedness, promoting climate-resilient healthcare facilities, building capacities of health professionals, and most crucially, it advocates an intersectoral, collaborative approach between the health sector and other climate-sensitive domains.¹⁴ At the core of public health systems are the grassroot primary healthcare providers who occupy a pivotal position in addressing the public health challenges posed by climate change through both adaptation and mitigation efforts. Their unique roles at the intersection of clinical practice, public health, and community engagement render them indispensable stakeholders in formulating comprehensive, health-centric responses to the climate crisis. Therefore, it is imperative, to empower primary healthcare providers such as Accredited Social Health Activist (ASHA) and Urban Social Health Activist (USHA) with the necessary knowledge, tools, and resources vital to mainstreaming climate action within healthcare systems.¹⁵ A compelling case study exemplifying the potential contributions of primary healthcare workers in tackling the climate crisis can be found at the Noolpuzha Primary Health Centre (PHC) in Wayanad district, Kerala. The PHC has adopted ecofriendly practices such as rainwater harvesting, waste management, and energy efficiency measures, reducing its environmental footprint. Simultaneously, healthcare providers have received training on the health impacts of climate change, enabling them to deliver tailored counselling and care for climate-sensitive conditions. This multifaceted approach demonstrates how primary healthcare workers can serve as a catalyst for climate action.

To conclude, climate change represents an unprecedented threat to global public health, with far-reaching and multidimensional impacts that transcend national and international borders. The effects manifest through diverse pathways - from increasing extremes of heat and weather disasters to the spread of infectious diseases and the disruption of food and water systems. Developing an effective response requires understanding the intricate ways climate change undermines human health and well-being across varied populations and geographical areas. It necessitates innovative collaborations between health professionals, climate scientists, policymakers, community leaders, and stakeholders across industries to develop holistic solutions. Comprehending the scope and scale of these climate-health linkages, while formulating equitable adaptation and mitigation strategies, is perhaps the most crucial public health endeavour of the 21st century. Rising to confront this defining challenge will not only safeguard human lives but also determine the future resilience and sustainability of communities and health systems worldwide.