Dr. Shyam P Lohani

The social and environmental determinants of health such as clean air, safe water, enough food, and secure shelter are profoundly influenced by climate change. It has been estimated that between 2030 and 2050, the temperature change may cause about 250,000 further deaths each year due to malnutrition, malaria, diarrhea, and heat stress (WHO, 2020). Climate change is anticipated to cause a direct loss of US$2-4 billion per year by 2030. This excludes losses in other health determining sectors such as water, sanitation, and agriculture.
Globally, climate change has already impacted human health profoundly. The direct effects are mediated via changes in extreme events like heat waves, drought, and heavy rain that result in heat and cold-related diseases, unintentional injuries and deaths, and other adverse health outcomes. While the indirect effects on health are mediated through climate change impacts on ecosystems and human systems, with health impacts from vector-borne, foodborne, and waterborne diseases, respiratory illnesses, occupational health and safety challenges, malnutrition, and negative impacts on mental health and wellness.

Impacts
It ought to be noted that temperature change is not the sole environmental drawback inflicting widespread health issues. This might result that crop yields will fall by 20-40 per cent with rising temperatures, thus exacerbating existing food shortages that are already leading to malnutrition and the deaths of 3.5 million people annually. Similarly, with the change in rainfall pattern, 16 per cent of people in developing countries who currently do not have access to clean water, and 48 per cent who lack access to adequate sanitation, a situation that will lead to further deterioration.
The Earth’s surface has warmed by about 0.6°C in the last three decades and it has been predicted that further rises between 1.1°C and 6.4°C may occur over the 21st century. Therefore, the rising temperatures will be responsible for the increased population of mosquitoes, a series of heat waves causing heatstroke, and increased cases of dengue fever, gastroenteritis, and other climate-sensitive infectious diseases. Some 300 million more people will have been affected by malaria by 2080.
Major weather-related disasters such as floods, drought, fires, and cyclones that have affected more than two billion people over recent years are also expected to rise. Mass environmental disruption, displacement, and migration of people and rapid and unplanned urbanisation are often the results of extreme climate change. Urbanisation in turn potentially exposes people’s vulnerability to climate change, especially when settlements are not designed to be climate-friendly.
Nowadays pollution of the air, water, and soil is the largest environmental determinant for sickness and death worldwide. This may have resulted in nine million premature deaths every year. Climate change, along with different natural and human-made health stressors, influences human health and diseases in varied ways that include some existing health threats that will intensify and new health threats may emerge. People are affected to a different degree as per their age, economic status, and location.
Public health will be suffering from disruptions of physical, biological, and ecological systems, together with disturbances originating from anywhere in the world. The health effects of those disruptions include respiratory and cardiovascular diseases, injuries and premature deaths associated with extreme weather events, changes within the prevalence and geographical distribution of food- and water-borne illnesses and different infectious diseases, and threats to mental health and wellbeing.
The impacts of weather and climate on human health are prominent but vary as per different factors. Exposure to health hazards related to climate change is not universal and affects different people and diverse communities to varied degrees. Moreover, exposure to multiple climate change in the same environment may result in compounding or cascading health impacts.
The frequency, severity, duration, and location of weather and climate phenomena such as rising temperatures, heavy rains and droughts, and some other kinds of severe weather conditions are already fluctuating due to climate change throughout the world. This may result in effects on areas already experiencing health-threatening weather and climate phenomena, such as severe heat or hurricanes, are likely to experience worsening impacts with higher temperatures and increased storm intensity, rainfall rates, and storm surge.
It additionally means some locations can experience new climate-related health threats. For instance, areas previously unaffected by harmful waterborne diseases as a result of cooler water temperatures might face these hazards in the near future as increasing water temperatures enable the organisms that cause these health risks to thrive. Therefore, areas that currently experience health threats may see a shift in the timing of the seasons that pose the greatest risk to human health.

Collaborative action
Climate change will thus have an effect on human health in two main ways. First, by ever-changing the severity or frequency of health issues that are already suffering from climate or weather factors; and second, by making new or unforeseen health issues or health threats in places where they may not have previously occurred. A rapidly changing climate has profound implications for every aspect of human life. It exposes vulnerable populations to extremes of weather, altering patterns of infectious disease, and impacting food security, safe drinking water, and clean air.
High temperatures are expected to cause public health disasters in the future as well. Their effects on global ecosystems and food production cannot be undermined which is causing more extreme weather events and wildfires, threatening communities, and creating the perfect conditions for deadly diseases to spread. Therefore, every stakeholder throughout the world is responsible for immediate action on reversing the increase in global temperatures. Immediate and collaborative actions on climate change, therefore, are imperative not just for the environment but for human health, too.

(A Professor, Lohani is the founder and academic director of Nobel College. lohanis@gmail.com)