More than half of human diseases caused by pathogens have at some point been made worse by the kind of impacts associated with the climate crisis, a comprehensive new study of the link between disease and climate hazards has found.
Diseases such as Zika, malaria, dengue fever, chikungunya and even Covid-19 have been worsened by climate impacts such as heat waves, wildfires, extreme rainfall and flooding, according to the document. In all, there are more than 1,000 different pathways for these various impacts to worsen the spread of the disease, a cavalcade of threats “too numerous for comprehensive societal adaptations,” the researchers wrote.
Global warming and changing precipitation patterns are expanding the range of disease vectors such as mosquitoes, ticks and fleas, resulting in the spread of malaria, Lyme disease, West Nile virus and other conditions .
Storms and floods have displaced people, bringing them closer to pathogens that cause outbreaks of gastroenteritis and cholera, while climate impacts have weakened humans’ ability to cope with some pathogens – drought, for example. example, can lead to poor sanitation, resulting in dysentery, typhoid fever and other diseases.
“We are opening a Pandora’s box of disease,” said Camilo Mora, a geographer at the University of Hawaii who led the research. “Because of climate change, we have all these triggers all over the world, over 1,000 of them. There are diseases just waiting to be released. stick to a lion – at some point the lion will come and bite our ass.
The researchers combed through more than 70,000 scientific articles analyzing the links between the various climatic hazards and infectious diseases. Some of these articles examine evidence dating back 700 years, before the advent of the man-made climate crisis. Of the 375 different infectious diseases mentioned in these articles, the researchers found that 218, more than half, were made worse by climate impacts made more common by global warming.
A smaller proportion of infectious diseases, about 16%, were reduced by climate impacts, according to the document, published in Nature Climate Change. Kira Webster, co-author of the study, said that as the disease database has grown “we have become both fascinated and distressed by the overwhelming number of case studies available that already show how vulnerable we are becoming to our growing greenhouse gas emissions.” .
Mora said the climate crisis has likely worsened the spread of Covid in several ways, such as habitat disruption from fires and floods that dislodge wildlife, such as disease-carrying bats, into new areas. closer to humans. Mora said he himself suffered from chronic joint pain after contracting chikungunya during an outbreak in Colombia a few years ago after a period of heavy rains caused an explosion in mosquito numbers.
“If there are pathogens that harm us, climate change is trying to hit all of them,” he said. “To me, it’s shocking that we don’t take this more seriously.”
The World Health Organization has warned that the climate crisis “threatens to undo the past 50 years of progress in development, global health and poverty reduction” and estimated that an additional 250,000 people will die each year from 2030 to 2050 due to proliferating diseases such as malaria and diarrhoea, as well as malnutrition and heat stress.
The new research is an “impressive extraction of what has been studied to demonstrate that climate shocks, taken together, make our already daunting task of fighting microbes more difficult,” said Aaron Bernstein, the center’s director for the climate, health and the global environment at Harvard University, who was not involved in the study.
“Climate science has shown that climate change is increasingly making parts of the world too hot, too dry, too wet, and ultimately too unsuitable for people to support themselves,” Bernstein added.
“Mass migrations of people can trigger infectious epidemics of all kinds, from meningitis to HIV. In short, an unstable climate creates fertile ground for infectious diseases to take root and spread.