Climate Change and Health Security: Infectious Links

Climate change is the "single biggest health threat facing humanity." But government action to prevent and prepare for the infectious links between climate change and health security is still lagging behind. The devastating health impacts of weather extremes, battering countries across the world this summer, might help to raise awareness for the myriad of ways climate and environmental change impact human health. Apart from an increase in extreme weather events, three other key factors stand out.  

There is clear evidence that climate change increases the frequency and intensity of extreme weather events, such as heat waves, floods, and droughts. The impact of these weather extremes on human health and well-being can be devasting.

According to data of the European Climate and Health Observatory, during the past 20 years, global heat-related mortality in people older than 65 years has nearly doubled, accounting for about 300,000 deaths in 2018. While NASA estimates that the regions most affected will be South Asia, the Persian Gulf, and the Red Sea by around 2050, and Eastern China, parts of Southeast Asia, and Brazil by 2070, the US and Europe will also increasingly feel the heat. The unprecedented heat wave engulfing Europe this summer is – as put by an expert of the World Meteorological Organization (WMO) – only a "sample of what is to come". The death toll has been devastating, with more than 2,000 people dying in Spain and Portugal within only roughly a week in July.

Another example illustrating the deadly consequences of extreme weather events are deaths from drowning during floods, costing thousands of lives over the past year. Examples include Pakistan, where flash floods killed more than 1,100 people in summer 2022, or Germany's Ahr valley, where 184 people lost their lives in floods in July 2021.

Even when not deadly, health effects of extreme weather events can be severe. Examples include heat strokes, cardiovascular diseases, lung diseases from wildfire smoke, and food- and waterborne illnesses caused by the contamination of water with harmful bacteria and viruses, leading to diseases like diarrhea.

Climate change increasingly fuels global hunger. Rising temperatures, changing rainfall patterns, and the greater frequency of extreme weather events undermine the four pillars of food security: availability, affordability, quality, and sustainability. In addition to the ripple effects of the Covid-19 pandemic and Russia’s war against Ukraine on food prices and supply chains, climate change is a major factor in the current "seismic hunger crisis". 45 million people currently face acute food insecurity and 50 million starvation. The direct impact of global warming on food security is, for example, visible in the devastating situation at the Horn of Africa. Suffering from one of the worst droughts in decades, the region is experiencing one of the most horrific hunger crises of the last 70 years with more than 37 million people facing acute hunger.

The health impact of food insecurity is severe. According to the World Health Organization (WHO), around 45 percent of deaths among children under the age of five are linked to undernutrition. Even when not life-threatening, malnutrition impairs physical and mental development and increases the risk of diseases. Undernourished mothers are more likely to give birth to babies who are underweight. Malnutrition in the first 1000 days of a child’s life can lead to impaired growth and development, holding children back from reaching their physical and cognitive potential.

Climate change exacerbates the risk of infectious diseases and pandemics. New studies show that climate hazards can aggravate more than half of the infectious diseases humans come in contact with. Changes in temperatures and rain patterns affect, for example, the geographic range of mosquitoes as well as the seasonality and severity of viral diseases carried by them. Since climate change will force many species to leave their natural habitats, new instances of viruses crossing between species will multiply and increase the risk of spillovers to humans. Climate change may thus become the "single biggest upstream driver of pandemic risk."

A growing body of research highlights the impact of climate change on mental health. In a recent policy brief, the WHO shows how climate change exacerbates different social and environmental risk factors for mental health, such as the loss of livelihood. Building on that, it illustrates how climate change can lead to the development of new or the worsening of pre-existing mental health conditions, such as depression and anxieties. Concepts like ecological grief, eco-anxiety, and solastalgia capture feelings of loss, helplessness, and distress about environmental degradation, experienced by a growing number of people across the world.

All of these health implications of climate change share a common characteristic: vulnerabilities are profoundly unequal. Fragile and disadvantaged groups of society are disproportionally affected. And lower-income countries not only possess fewer resources to prepare for and adapt to climate change, their healthcare systems and economies are also frailer, reducing their capacities to address climate-related health security risks. Health equity must therefore be at the heart of a comprehensive policy response to the increasing health risks from climate change. An effective policy response also needs to integrate human, animal, and environmental health. The multisectoral concept of "One Health" that recognizes that very interconnectedness has recently gained traction among governments and international organizations.  

Of course, without broader climate action, health crises will only aggravate. That is why the Paris Climate Agreement is a "fundamental public health agreement, potentially the most important public health agreement of the century." Efforts to achieve net zero targets so far remain insufficient. Yet, the fact that people across the world, including in the US and Europe, are increasingly feeling the health impacts of climate change may help to spur climate action – and improve both climate and health security.

Julia Hammelehle is a Policy Advisor with the Munich Security Conference (MSC). For her work, she focuses primarily on EU politics, EU-UK relations, German foreign and security politics, Transatlantic relations, and energy foreign policy.

Before joining the MSC, she studied International Relations in Dresden and Boston and pursued a Master’s degree in EU Politics at the London School of Economics and Political Science (LSE). During her studies, she gained work experience in, amongst others, the House of Commons, the German Bundestag, the State Parliament of Baden-Württemberg, and the Max Planck Institute for Comparative Public Law and International Law.