Climate change pushing animals to migrate, increasing risks of new pandemics, study finds

With a highly contagious avian flu killing millions of birds across a nation still coping with the COVID-19 pandemic, weary residents may not want to hear that climate change is greatly increasing the risk of new disease outbreaks.

But that’s the warning from a team of researchers who published a study last week in the journal Nature.

The warming climate is forcing animals to move outside their typical home ranges, increasing the risk any of the thousands of infectious viruses animals carry could be transmitted to other species they haven’t encountered before, the study concluded. And that poses a threat to human and animal health around the world.

To limit such interactions, the world should curb rising temperatures and more closely monitor wildlife populations to identify potential viruses, warned the pair of Georgetown University researchers who co-led the team, Colin Carlson and Gregory Albery.

“Climate change and pandemics are not separate things,” Carlson, an epidemiologist and assistant professor, told USA TODAY. “We have to take that seriously as a real-time threat.”

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Their paper is the second major study in three months to call for action to prevent the next pandemic before it makes the leap to people.

Tens of millions of chickens have been killed in an effort to stop the spread of a highly pathogenic strain of avian flu.

Hours after the study was released early last Thursday, Carlson was among several experts who testified before a U.S. House oversight subcommittee hearing on preventing pandemics through wildlife-borne disease surveillance. They spoke of the need to beef up monitoring, research and data sharing among state and federal agencies.

The nation faces a substantial threat, Carlson told the committee. “Climate change is creating numerous hot spots of future pandemic risk right in our backyard.”

Even though the risks are greater in Southeast Asia and Africa, Carlson pointed to such risks in the U.S. as the emergence of bubonic plague in the West and the origins of the 1918 flu pandemic on a military base in Kansas.

A study released in February warned of similar consequences, concluding it’s far more economical to prevent a pandemic by increasing virus surveillance than to treat it. Two of that study's co-authors said this week that they’ve been disappointed by the lack of action to prevent the next outbreak.

“Quite clearly our response to COVID has not been an unqualified success,” said Stuart Pimm, the Doris Duke Professor of Conservation Ecology at Duke University. “We need to be very serious about the fact that COVID will not be the last (pandemic).” 

Pimm said the U.S. could strongly encourage other countries through its foreign aid programs to tackle pandemic prevention by slowing deforestation, improving monitoring and going after traders in illegal wildlife.

One of his co-authors, Aaron Bernstein, interim director of the Center for Climate, Health and Global Environment at Harvard University, said, “We have seen glimmers of progress but primary prevention of pandemic risk has not made it anywhere near where it needs to be.”

This latest paper makes it “even more clear than before that our approach to pandemics cannot solely rely on waiting until outbreaks start and then hope to contain them once they do,” Bernstein said. Protecting habitats, taking serious action to curtail the wildlife trade and improving biosecurity for livestock “are cornerstone measures to prevent pandemics that conserve species and reduce greenhouse gas emissions at the same time.”

An international group of researchers said the world should focus on monkeys, rats and bats to identify and prevent the spread of the next pandemic.

House committee members had questions of their own in Thursday's hearing, bringing up a mysterious illness that has killed 85 horses in a federal corral in Colorado, the millions of chickens killed to prevent the spread of the avian flu, and the spread of disease by mink.

Pandemics are considered “one of the preeminent threats to the nation’s security,” Catherine Semcer, research fellow with the Montana-based research institute Property and Environment Research Center, told the committee. Like the authors of the February paper, Semcer said the nation needs to crack down on illegal wildlife tracking and help other nations do the same.

The representatives quizzed presenters about how to prevent viruses spreading from animals to people, including through collaboration among state and federal agencies.

Anne Kinsinger, the U.S. Geological Survey’s associate director for ecosystems, told the committee the agency is collaborating with the Fish and Wildlife Service to develop a national biosurveillance network.

It will encompass all aspects of wildlife disease surveillance, including predicting threats and assessing the possible effects, Kinsinger said. The survey also is developing an expanded national wildlife disease database with funding from the American Rescue Plan Act.

Rep. Katie Porter, D-Calif., said she plans to sponsor legislation to direct more money and support to efforts to improve surveillance and coordination among federal agencies and hopes she will find bipartisan support.

The team of researchers working with Carlson and Albery simulated animal movement, risk factors and potential hot spots that could result in new viral transmissions over the next 50 years under a range of climate scenarios. Even the mildest warming could drive the spread of disease, they said. 

And, as they found, animals are already on the move. Bird and butterfly ranges are changing. Right whales forage farther north.

Some animals could shift their boundaries by as much as 60 miles or more, bringing their parasites and pathogens with them to water holes and other sites where they may contaminate other animals, Carlson said. And that poses “a measurable threat” to wildlife and human health.

Researchers expect to see hot spots in Southeast Asia and Africa. They concluded there’s “an urgent need” to pair viral surveillance with monitoring the shifting ranges of animals, especially in the tropical regions of the world, which harbor the greatest potential for viral transmission and are experiencing rapid warming.

The study focused solely on mammals and doesn’t include the additional risks of viruses that could come from birds, reptiles and amphibians.

“This work provides us with more incontrovertible evidence that the coming decades will not only be hotter but sicker,” said Albery, a disease ecologist.

Climate change will be the biggest driver of disease emergence, the researchers said, and will increase the risk of viral disease transmission at the same time warming temperatures are expected to leave people and animals more susceptible to infection.

“We need to put measures in place to build health infrastructure and protect animal and human populations,” Albery said. “Critically, this bolstered infrastructure needs to be paired with active surveillance of wild animals, their movements, and their diseases to ensure that we can keep our finger on the pulse of global change.”