Climate impacts worsen widespread human disease | Climate Crisis

More than half of human diseases caused by pathogens have been exacerbated at some point by impacts linked to the climate crisis, a new exhaustive study of the link between disease and climate hazards has found.

The paper found that diseases such as Zika, malaria, dengue, chikungunya and even Covid-19 are all exacerbated by climate impacts such as heatwaves, wildfires, extreme rainfall and flooding. Collectively, these disparate effects have more than 1,000 different pathways to worsen the spread of the disease, the researchers write, a set of threats that are “too many for full-scale social adaptation.”

Global warming and changes in rainfall patterns are expanding the reach of disease vectors such as mosquitoes, ticks and fleas, leading to the spread of malaria, Lyme disease, West Nile virus and other diseases.

Storms and floods displace people and bring them closer to the pathogens that cause gastroenteritis and cholera outbreaks, while climate impacts impair the ability of humans to cope with some pathogens – for example, droughts can lead to poor sanitation, leading to diseases such as dysentery, typhoid fever, etc. .

“We’re opening a Pandora’s box of disease,” said University of Hawaii geographer Camilo Mora, who led the study. “We have all these triggers all over the world, more than 1,000 of them, because of climate change. There are diseases out there waiting to be unleashed. It’s like we’re poking a lion with a stick — at some point, the lion will come over bite our ass.”

The researchers combed through more than 70,000 scientific papers analyzing the links between different climate hazards and infectious diseases. Some of these papers look at evidence dating back 700 years, before the human-caused climate crisis. Of the 375 different infectious diseases mentioned in these papers, the researchers found that 218, more than half, were exacerbated by climate impacts that have become more prevalent as a result of global warming.

According to the paper published in Nature Climate Change, a smaller proportion of infectious diseases (about 16%) have been reduced due to climate impacts. As the disease database grows, “we are both fascinated and distressed by the large number of case studies available that already show how vulnerable we are to growing greenhouse gas emissions,” said study co-author Kira Webster.

Mora said the climate crisis may have exacerbated the spread of the new coronavirus in a number of ways, such as the disruption of habitats by fires and floods and the expulsion of wildlife such as disease-carrying bats into new areas closer to humans. Mora said his own joints had been suffering from persistent pain following an outbreak of chikungunya in Colombia a few years ago, followed by a period of heavy rainfall that led to a surge in mosquito populations.

“If there are pathogens that do us harm, climate change is trying to touch every pathogen,” he said. “It’s shocking to me that we’re not taking this more seriously.”

The World Health Organization has warned that the climate crisis “has the potential to undo the progress made in development, global health and poverty reduction over the past 50 years”, and estimates that between 2030 and 2050, 250,000 people will die each year from the spread of the disease. Examples include malaria and diarrhoea, as well as malnutrition and heat stress.

Aaron Bernstein, director of the U.S. Center for Climate, Health and the Global Environment, said the new study is “an impressive dig at what’s being studied to demonstrate that climate shocks in general have transformed our daunting task of fighting microbes. more difficult.” Harvard University, who was not involved in the study.

“Climate science shows that climate change is making more parts of the world too hot, too dry, too wet, and ultimately too unsuitable for people to survive,” Bernstein added.

“Mass movement of populations can trigger outbreaks of infectious diseases ranging from meningitis to HIV. In short, unstable climates create fertile ground for infectious diseases to take root and spread.”

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