Climate change is making infectious diseases worse, according to a ‘truly scary’ study 

Over half of all known infectious diseases that threaten humans have been worsened by climate change, according to an alarming new study.

Researchers analysed how 10 different climate emergencies—for instance, heatwaves, droughts and wildfires—impact hundreds of infectious diseases. The study concluded that 58% of diseases have been exacerbated by climate change. These include dengue, hepatitis, pneumonia, malaria, Zika and anthrax, to name a few.

“It was truly scary to discover the massive health vulnerability resulting as a consequence of greenhouse gas emissions,” said Camilo Mora, a professor at the University of Hawaii and the lead author of the study. The research was carried out by a team at the University of Hawaii at Manoa and published in Nature Climate Change, a peer-reviewed scientific journal.

In conducting the study, the researchers analysed how the various climate hazards impact vectors of disease transmission and the pathogenic diseases that are then exacerbated. The report was accompanied by an interactive website that allows users to explore over 1,000 pathways of amplified disease spread.

Droughts, for instance, cause mosquitoes—common vectors of disease transmission—to concentrate around limited water sources, increasing the likelihood of diseases like West Nile to proliferate. Environmental degradation and natural habitat loss is also forcing disease-carrying animals, like rodents and bats, to live nearer to humans. The close proximity is aggravating the threat of diseases like hantavirus and Nipah virus.

Meanwhile, global warming is causing ice caps and permafrost to melt, exposing pathogens that have long been frozen underground.

Instances of this occurrence are already well documented. In 2016, for example, a 12-year-old boy was killed in Russia after becoming infected by anthrax. The disease was traced back to an infected reindeer carcass that had been frozen underground, but emerged and thawed due to temperatures in the Siberian tundra reaching up to 35°C that summer. Nearly 20 other people also ended up in hospital because of the outbreak.

“As our database started to grow and we could see our network of connections between hazards and disease grow, we became excited by the magnitude of the human vulnerability,” Mora and co-author Tristan McKenzie told the World Economic Forum. “By the end, when the full figure of connections was all set and done, one could not stop but feel scared.”

The Nature Climate Change study concluded that curbing greenhouse gas emissions is essential to mitigating climate change-induced disease spread. “Our paper makes it clear that the number of diseases and pathways in which outbreaks can be triggered are too numerous for full adaptation,” Mora and McKenzie stated, stressing the “urgent need” to reduce emissions worldwide.

“We also knew that as we add more greenhouse gases this can also become worse," the researchers added. “A terrifying thought.”

Aggravated infectious diseases are not the only threat to public health that is intensifying because of climate change. Dr. Shyam Bishen, head of health and healthcare at the World Economic Forum, explained that climate change is exacerbating an array of health issues, including injuries and premature deaths related to extreme weather events, increased respiratory and cardiovascular disease, and deteriorating mental health.

Moreover, Bishen noted that climate change-related health risks are disproportionately felt by the most vulnerable and disadvantaged, including the elderly, poor communities and ethnic minorities. “While no one is safe from these risks, the people whose health is being harmed most by the climate crisis are the people who contribute least to its causes, and who are least able to protect themselves and their families against it,” Bishen stated.