The Deadly Impact of Climate Change on Human Health

In the past year, over 1,000 people have died from cholera in Malawi. Cholera is a preventable disease that is easy to treat, but the outbreak in Malawi has been more deadly than any in the past.

Climate change is at least partly to blame for the increase in cholera cases. The series of cyclones and storms that began in January 2022 caused floods, deaths, and displacement across the region. World Weather Attribution, a group of scientists that assesses the role of climate change in extreme weather events, said in April that global warming had made those storms wetter and more intense than they would otherwise have been, hitting already vulnerable communities harder. That, in turn, has led to outbreaks of disease that are worse and harder to stem than would otherwise be the case.

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"There is a clear link between climate and health outcomes," said Madeleine Thomson, head of climate impacts and adaptation at the Wellcome Trust, a health research charity. "But the health community is not yet geared up to use climate information in their programs." Though the link between climate and health outcomes is not yet well understood by practitioners, the connections are increasingly clear. Heat waves, for example, cause thousands of deaths each year, with many falling victim because their homes aren't adapted to hotter weather. The 2022 heatwave in Europe led to more than 20,000 excess deaths. By better understanding the link between climate and health, we can begin to take steps to protect people from the harmful effects of extreme weather and other climate-related health risks.

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Droughts can have devastating consequences, including starvation and reduced nutrition, which can cause long-term developmental challenges for children and often outright death. Millions in the Horn of Africa, across Djibouti, Ethiopia, Kenya and Somalia, are suffering from the longest drought in 40 years. There are also diseases that are caused by viruses, bacteria and parasites, but carried to humans by mosquitoes, ticks or the like. Warmer temperatures mean some of these vectors are able to survive and explore newer regions, causing the disease to spread further than before. Climate change also increases the risk of pandemics, with growing human-animal contact driven by disruptions to ecosystems.

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Cholera is a disease of poverty and poor infrastructure. The strains of bacteria that cause cholera spread through the fecal-oral route, which tends to happen in places where there is a lack of access to clean water and poor hygiene. Treating cholera requires oral rehydration solution (ORS), a mix of salts and sugar delivered in clean water. However, when a flood or drought displaces large populations, delivering either clean water or ORS becomes harder and makes outbreaks worse. Cholera outbreaks have happened not just in Malawi, but also in flood-hit Pakistan, Nigeria, and Mozambique in just the last few months.

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A study of cholera's link to contaminated water in London in 1854 by physician John Snow gave rise to the field of epidemiology, the study of disease patterns and prevalence in a population. More than 150 years later, climate change is adding a new dimension to the epidemiological outcomes of cholera.
According to Thomson, the global health community is still quite naïve when it comes to climate change. However, this is beginning to change as more and more people are becoming aware of the importance of climate change.

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In October, the World Health Organization (WHO) and the World Meteorological Organization (WMO) launched a platform with funding from the Wellcome Trust to provide people with information they can use to save lives. Many of the solutions are straightforward, such as improving early warnings of extreme-weather events and offering more advice on what to do if you’re affected, but remain hard to execute because the right information isn’t with the right people. The WHO and WMO are working to change this by making sure the right information is available to the people who need it most. With this platform, they hope to improve communication and coordination between different organizations and agencies, as well as provide people with the resources they need to protect themselves and their families.

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"There is a disconnect between public health practitioners and climate experts," said Joy Shumake-Guillemot, who leads the WMO-WHO joint effort. "Practitioners lack access to the training and tailored climate information they need to address growing issues, while climate experts have troves of research and resources that could be applied to support public health goals but aren't reaching the right people."

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Malawi is one of the poorest countries in the world, which is one reason why it struggles with diseases like cholera in the first place. As the country gets richer and builds better infrastructure, cholera should be banished. But climate change means that its basic development goals have now become harder to achieve, which means cholera could continue its rampage for longer. That's not a world Malawi deserves, having contributed essentially nothing to the greenhouse gases accumulated in the atmosphere.