By Oladosu Adebola
Climate change, driven by human activities, is an existential threat that profoundly impacts global health. The changing climate exacerbates existing health challenges and introduces new risks through a variety of mechanisms, including increased frequency of extreme weather events, rising temperatures, altered precipitation patterns, and sea-level rise. This comprehensive review critically analyzes the multifaceted impact of climate change on global health, supported by statistical evidence.
Rising global temperatures due to climate change have resulted in more frequent and severe heatwaves, directly impacting human health. According to the World Health Organization (WHO), heatwaves caused over 70,000 excess deaths in Europe during the summer of 2003 alone. In the United States, heatwaves cause more deaths annually than all other weather-related events combined, with an average of 702 heat-related deaths each year between 2004 and 2018 (Centers for Disease Control and Prevention, CDC).
The Intergovernmental Panel on Climate Change (IPCC) projects that global temperatures could rise by 1.5°C to 2°C by the end of the century. This rise in temperature is expected to increase the incidence of heat-related illnesses and deaths, particularly among vulnerable populations such as the elderly, children, and those with pre-existing health conditions. For instance, a study by Gasparrini et al. (2015) estimated that heat-related mortality could increase by 257% in cities across Europe by the 2080s under a high emissions scenario.
Climate change affects the distribution and transmission dynamics of vector-borne diseases, such as malaria, dengue fever, and Lyme disease, by altering the habitats and life cycles of the vectors (e.g., mosquitoes and ticks). The WHO estimates that climate change could expose an additional 2 billion people to dengue transmission by the 2080s.
Malaria, a major public health concern in sub-Saharan Africa, is highly sensitive to climatic conditions. The disease transmission is influenced by temperature, humidity, and rainfall patterns.
According to the IPCC, suitable transmission conditions for malaria could expand in highland areas of East Africa and decrease in some regions where temperatures become too high for the malaria parasite. Research by Caminade et al. (2014) suggests that climate change could result in a net increase of 5-7% in malaria exposure by the end of the 21st century, affecting tens of millions more people annually.
Climate change exacerbates waterborne diseases through increased rainfall, flooding, and contamination of water supplies. Diseases such as cholera, typhoid fever, and diarrhea are more prevalent during heavy rainfall and flooding events, which are becoming more frequent and intense due to climate change. The WHO reports that waterborne diseases cause 3.4 million deaths annually, with children under five being the most affected.
Flooding events not only contaminate drinking water sources but also overwhelm sanitation infrastructure, leading to outbreaks of diseases like cholera. For example, during the 2010 floods in Pakistan, over 164,000 cases of acute watery diarrhea were reported, with cholera being a significant concern (WHO).
Climate change adversely affects food security by impacting agricultural productivity, which in turn affects nutrition and health. Changes in temperature, precipitation, and the frequency of extreme weather events disrupt crop yields, leading to food shortages and higher food prices. The Food and Agriculture Organization (FAO) estimates that climate change could reduce global agricultural yields by up to 30% by 2050.
Malnutrition, particularly in developing countries, is exacerbated by climate-induced food insecurity. According to the United Nations International Children’s Emergency Fund (UNICEF), 144 million children under the age of five were stunted in 2020, a condition linked to chronic malnutrition. Climate change threatens to increase this number significantly by reducing the availability of nutritious food and impairing livelihoods.
Air pollution, exacerbated by climate change, poses significant risks to respiratory and cardiovascular health. Increased temperatures contribute to the formation of ground-level ozone and particulate matter, which are harmful pollutants. The WHO estimates that air pollution causes 7 million premature deaths annually, primarily due to respiratory and cardiovascular diseases.
Wildfires, which are becoming more frequent and intense due to climate change, also contribute to poor air quality. For instance, the 2019-2020 Australian bushfire season resulted in 33 direct fatalities and an estimated 417 excess deaths due to smoke inhalation (Johnston et al., 2020).
Similarly, the 2020 California wildfires led to widespread air quality deterioration, causing respiratory problems for thousands of people.
The psychological impact of climate change is an emerging area of concern. Climate-related events such as hurricanes, floods, and wildfires can lead to significant mental health issues, including anxiety, depression, and post-traumatic stress disorder (PTSD). The American Psychological Association (APA) highlights that climate change acts as a “threat multiplier,” exacerbating existing mental health issues and creating new ones.
A study by Obradovich et al. (2018) found that an increase in average monthly temperatures and the occurrence of natural disasters are associated with a rise in mental health issues. For instance, Hurricane Katrina in 2005 had long-term psychological impacts on the affected populations, with increased rates of PTSD and depression observed even years after the event (Kessler et al., 2008).
Addressing the health impacts of climate change requires coordinated global action. International agreements such as the Paris Agreement aim to limit global warming to well below 2°C above pre-industrial levels, which is crucial for mitigating health risks. Countries are also developing national adaptation plans to strengthen health systems’ resilience to climate change.
Health systems need to be strengthened to cope with climate-related health risks. This includes improving infrastructure, enhancing disease surveillance, and training healthcare workers. The WHO has developed the Health and Climate Change Country Profiles to assist countries in assessing their vulnerabilities and preparing for climate-related health impacts.
Community-based adaptation strategies involve engaging local communities in climate resilience efforts. These strategies include promoting climate-smart agriculture, improving water management practices, and raising awareness about climate change and health. Programs like the Community-Based Adaptation to Climate Change (CBA) projects have shown success in enhancing resilience at the grassroots level.
Climate change poses a significant threat to global health through a variety of mechanisms, including heat-related illnesses, vector-borne diseases, waterborne diseases, food insecurity, respiratory and cardiovascular diseases, and mental health issues. The statistical evidence underscores the urgent need for coordinated global action to mitigate these impacts. Strengthening health systems, enhancing disease surveillance, promoting community-based adaptation, and international cooperation are critical strategies to protect public health in the face of climate change. Addressing these challenges requires a comprehensive and sustained effort to ensure the health and well-being of populations worldwide.
Oladosu Adebola Oluwaseun is an environmental journalist and a Post graduate student of the International Institute of Journalism (IIJ)
