Bird Flu Is Picking its Way Across the Animal Kingdom—and Climate Change Could Be Making it Worse

On Monday, Texas health officials confirmed an individual who had “direct exposure to dairy cattle” has contracted bird flu, marking the second reported human case of the H5N1 virus in U.S. history.

The person has only exhibited eye inflammation so far, and the CDC says risk to the public remains low. However, this highly pathogenic strain of avian influenza has scientists on edge for a variety of reasons. 

H5N1 was first detected in 1996, but the current highly pathogenic outbreak emerged in 2020 in Europe. Since then, the virus has spread across the world, flaring up particularly high during bird migrations in the fall and spring. As of March 27, the virus has infected more than 82 million farmed birds in the U.S. Overall, it’s the most severe bird flu outbreak in the country’s history. 

While the virus is adapted to most effectively infect birds, it can mutate and spillover into other species, including mammals. Scientists are still trying to figure out the factors making this outbreak so severe and how to contain it, but recent research shows that climate change and environmental destruction could be aiding the spread of avian flu—and a variety of other animal-borne illnesses. 

Agricultural Illnesses: Over the past few years, bird flu has devastated the poultry industry, causing an estimated loss of at least $1 billion in revenue for farmers (you may be feeling part of the impact of this as egg prices surge at supermarkets). Typically, when bird flu is detected at a chicken farm, the entire flock is euthanized, a practice that activists and many scientists believe is inhumane, writes Marina Bolotnikova for Vox. 

On March 25, the U.S. Department of Agriculture confirmed the presence of avian influenza in dairy cows in Texas and Kansas—and later, New Mexico. This is the first time cows infected with the virus have been detected, stumping scientists and stoking fear across the cattle industry. 

“The fact that they are susceptible—the virus can replicate, can make them sick—that is something I wouldn’t have predicted,” Richard Webby, an influenza virologist at St. Jude Children’s Research Hospital, told The New York Times. 

Officials say that consumers should not be concerned about commercial milk supplies, but recommend that dairy and beef farm workers practice biosecurity measures such as wearing protective gear. But the Texas Animal Health Commission noted that the disease is causing a decrease in viable milk production, which could drive losses across the dairy industry, reports the Texas Tribune. 

Wildlife Catastrophe: Outside the farm, bird flu has been picking its way through the animal kingdom. Since it first arose, H5N1 has been identified in a range of species including mink, dolphins, grizzly bears, foxes, and a polar bear.

It’s been especially devastating for marine mammals; in Argentina, bird flu killed 17,400 southern elephant seal pups, roughly 96 percent of all young born in 2023, researchers estimated. 

“We found silence and massive numbers of carcasses,” Marcela Uhart, a wildlife veterinarian at the University of California, Davis, told National Geographic. “All ages, new and old, just piled up on the beach where there should have been living, happy animals.”

While scientists have successfully vaccinated a small population of California condors against H5N1, there are virtually no strategies to mitigate the spread of bird flu in wild animals at the moment. 

The Climate Component: A few weeks ago, I wrote about the various ways climate change is throwing the seasons out of whack and how this can mess with animal migrations. It turns out that for birds, these changing migrations can contribute to the severity and spread of avian flu, according to the CDC and recent research. 

For example, climate change is shifting the range of some birds during the winter toward the poles, and spring migrations are happening earlier due to warming temperatures. This can increase the chances of something called “virus reassortment,” or the exchange of viral genetic material, if the species interacts with bird populations or different species they had rarely overlapped with before. 

Scientists are still parsing out the connection between climate change and avian flu. But it’s clear the highly pathogenic H5N1 strain has “moved outside the bounds of its typical seasons,” wrote Zoya Teirstein for Grist last year. 

“How come this virus is popping up in the middle of summer in the Mediterranean Sea or when it’s minus 20 or 30 in a commercial farm in Canada? There’s close to 80 countries in the world with this problem, we’ve never seen that before,” Jean-Pierre Vaillancourt, a professor in the department of clinical sciences at the University of Montreal in Canada, told Grist. “That’s why we’re seriously looking at climate change.” 

A growing body of research finds that climate change is fueling the spread of all sorts of zoonotic illnesses, including West Nile virus and malaria. On top of this, humans are increasingly encroaching on wild animal habitats through deforestation and development, which could expose us to the diseases these species carry. 

Stopping the Spread: Last March, in an article for Foreign Affairs, epidemiologist Caitlin Rivers detailed all of the ways that the U.S. could prepare for an intense bird flu outbreak, from restocking health supplies to scaling up vaccine production. Yesterday, she tweeted that the piece is “still relevant” today. 

Other public health experts have echoed Rivers’ call to action, urging the importance of early disease surveillance to stop outbreaks before they even begin. In the technology space, early experiments suggest that gene editing in chickens can protect poultry farms from flu outbreaks, reports Wired. 

More Top Climate News

For the past few years, the U.S. government has been ramping up efforts to revive the struggling nuclear industry, the latest being a $1.5 billion loan to restart a decommissioned nuclear plant in Michigan, announced by the Biden administration on Wednesday. The money will enable manufacturer Holtec International to upgrade the plant and keep it running until at least 2051, reports the Times. 

Some experts say that nuclear power could help meet the astronomical demand for electricity in the U.S. without releasing excess emissions. 

“Nuclear power is our single largest source of carbon-free electricity, directly supporting 100,000 jobs across the country and hundreds of thousands more indirectly,” Jennifer M. Granholm, Biden’s energy secretary, said in a statement on Wednesday. 

Meanwhile, officials are investigating the environmental impacts of the Francis Scott Key Bridge collapse in Baltimore, report Royale Bonds and Rona Kobell for the Baltimore Banner. 

Large amounts of steel and concrete fell into the Patapsco River during the collapse, and the ship that crashed into the bridge contained 1.5 million gallons of fuel and lube oil, which could affect fish and bird populations if too much leaks into the water, experts say.  

In breaking news, the National Oceanic and Atmospheric Administration (NOAA) announced today that a dead endangered North Atlantic right whale was spotted in the waters off Virginia, marking the fourth documented death in 2024. The female was at least 35 years old and had given birth to a calf earlier this year, which is not expected to survive on its own. Scientists from the University of North Carolina Wilmington are currently leading a necropsy to determine the whale’s cause of death. 

“The situation so far in 2024 for right whales highlights the fact that much more needs to be done to prevent the extinction of this species,” Amy Knowlton, senior scientist in the Anderson Cabot Center for Ocean Life at the New England Aquarium, who helped identify the whale, said in a statement. “It is frustrating that solutions that could address these threats are not being implemented more immediately.”

I’ve written several times about the main threats that North Atlantic right whales are facing—entanglement and vessel strikes—and ways that governments can help mitigate them.