Heat Stress, Mosquito-Borne Diseases, and Extreme Weather Events: How Climate Change Threatens Public Health
Government ministers from around the world are gathering at the annual U.N. climate summit COP28 to address a pressing issue – the impact of climate change on public health. Climate-driven health threats are now jeopardizing decades of progress made in improving global health. According to the World Health Organization (WHO), by 2030, malnutrition, malaria, diarrhoea, and heat stress alone could cause an additional 250,000 deaths per year worldwide.
The escalating risks to public health caused by climate change are becoming increasingly evident. Extreme weather events are becoming extreme health events, warns Martin Edlund, CEO of global health nonprofit Malaria No More. This article delves into the mounting health challenges faced by people across the globe due to climate change and offers insights into what the future may hold if urgent action is not taken.
Rising global temperatures are creating new conditions for disease-carrying mosquitoes. As temperatures warm and heavy rainfall becomes more frequent, mosquitoes carrying viruses such as dengue, malaria, West Nile, and Zika are expanding their territories. This has resulted in a rise in reported dengue cases, soaring from half a million in 2000 to over 5 million in 2019, as stated by the WHO. Brazil, for instance, saw a 73% increase in dengue cases this year compared to the five-year average, while Bangladesh experienced a severe dengue outbreak. The impact on malaria is also alarming, with 5 million more cases reported in 2022 than the previous year, reaching a staggering total of 249 million, as reported in the WHO’s World Malaria Report.
Aside from the proliferation of mosquito-borne diseases, climate change also contributes to the spread of other water-borne diseases during storms and floods. Cholera, a highly contagious intestinal infection transmitted through contaminated food and water, had seen impressive progress in recent years until climate change disrupted this trend. Last year, 44 countries reported cholera cases, representing a 25% increase compared to 2021, the WHO disclosed. Cyclones, floods, and droughts have compromised access to clean water, facilitating the growth of cholera-causing bacteria. Recent cholera outbreaks have proven to be deadlier, with fatality rates reaching the highest level in over a decade, according to the WHO.
Erratic rainfall patterns triggered by climate change have also raised the risk of diarrhoea, the second leading cause of death among children under the age of 5. Research has linked the intensified risk of diarrhoea to unpredictable rainfall patterns, which result in either excessively wet or dry conditions. Tragically, diarrhoea claims the lives of more than half a million children annually.
Heat stress is perhaps one of the most obvious health consequences of global warming. As temperatures continue to rise, it is projected that hundreds of millions of people will be affected by heat stress in the coming decades. A recent report by the Lancet medical journal revealed that in 2022, individuals experienced an average of 86 days with dangerously high temperatures due to the world already being 1.1C warmer than the preindustrial average. According to the report, if global temperatures rise by 2C, the number of heat-related deaths could more than quadruple. The devastating European heatwaves in 2022 alone resulted in an estimated death toll of 61,000 people, as published in the journal Nature Medicine.
Climate change-induced heat has also contributed to the increased frequency and intensity of forest fires. The drier conditions in forests have provided the perfect fuel for wildfires, which have ravaged large parts of the world in recent years. The resulting smoke from these fires has caused unhealthy levels of air pollution, exposing more than 2 billion people to dangerous levels of smoke pollution annually, according to a study in the journal Nature. The impact of wildfire air pollution has been particularly severe in the United States, where it is responsible for thousands of deaths each year.
The global impact of climate change on public health is profound and calls for urgent action. The discussion at COP28 is a crucial step toward tackling these climate-driven health threats. Governments must prioritize strategies that protect vulnerable populations, enhance disease surveillance and prevention, and invest in resilient healthcare systems. Only by joining forces and committing to climate mitigation and adaptation measures can we hope to safeguard public health and mitigate the disastrous consequences of climate change.
