Climate change is making superbug drug resistance worse: UN

The combo of climate change and antimicrobial drug resistance is teeing up superbugs as a potential leading cause of human death, a new United Nations report warns.

Unsubtly titled Bracing for Superbugs, and released Tuesday by the UN Environment Programme, it marks perhaps the global body’s most direct attempt yet to bring attention to the scary feedback loop linking global warming, the increase of antimicrobials in our food supplies, farm pesticides, and medicine with the spread of drug-resistant bacteria, fungi, and viruses. Curbing this spread will require considerable changes in how food is grown and diseases get treated, the report warns—agribusinesses, the pharmaceutical industry, and governments across the globe must rethink, in tandem, both their prolific use of antimicrobials and their climate footprint.

If the trend continues unchecked, the UN report argues that deaths from superbug infections could double by the year 2050—to 10 million a year, rocketing them past respiratory diseases and infections, diabetes, and blood diseases. Presently, around 10 million people die annually from cancer, the world’s second-leading cause of death. The report adds that this shift would also disproportionately affect lower-income communities, exacerbating the inequality gap in health outcomes by income.

“Antimicrobials are an essential part of modern life,” writes UN Environment Programme executive director Inger Andersen in the report. “Yet, the more we use them inappropriately, the more the microbial world adapts.”

Antimicrobial resistance, or AMR, occurs when microbes develop immunity to the substances created to extinguish them. Drug resistance is normal—to an extent. In fact, the UN’s report features a helpful chart illustrating why this is a century-old problem: It shows how, as antibiotics are commercialized, bugs have learned to become resistant—first, to sulfonamides, streptomycin, and penicillin in the 1930s; later to cephalosporin and vancomycin in the 1980s; and most recently to ceftolozane/tazobactam, a combination antibiotic, just seven years after their introduction in 2014. AMR has therefore long posed threats to humans, animals, and plants alike. But the UN’s report concludes that the stakes have gotten too high to ignore: “Failing to address the global burden of AMR, including its environmental dimensions, could take humanity back to an era when even mild infections could become deadly.”

The report discusses how climate change is compounding the century-old drug-resistance problem. Climate change is destroying the Earth, sure, but it’s separately also perpetuating more favorable conditions for microbes to develop resistance—denser mega-cities as people migrate, poorer sanitation, bigger piles of waste, more polluted waterways.

Rising temperatures are also equipping superbugs to thrive inside the human body. The normal body temperature is between 97 and 99 degrees, a range traditionally inhospitable to fungi, which, as a rule, grow best between 60 and 80 degrees. Climate change is selecting specimens that have adapted to higher temperatures. For instance, multidrug-resistant Candida auris, a fungus estimated to kill up to 60% of the people it infects, appears to have learned to function quite well at 98.6 degrees.

Thankfully, these infections haven’t risen to The Last of Us levels, but scientists warn they still add the risk of deadly complications to routine medical operations, where patients might need antibiotics afterwards. As superbugs grow more super, there are fewer effective treatments—and there’s often a good reason why heavier-duty treatments are known as “drugs of last resort.”

The UN’s report calls on corporate and government leaders to address sources of pollution worldwide, while also thinking about the ways they kill pathogens—whether that involves sewage or other kinds of municipal waste, drug manufacturing, or agriculture’s chemical-intensive farming practices. “Prevention is at the core of the action, and environment is a key part of the solution,” the report says. Comprehensive and coordinated action is needed to address what the organization now refers to as “the triple planetary crisis,” meaning the threats of climate change, pollution, and biodiversity loss.