Potential hotspots include the Sahel, the Ethiopian Highlands, the Rift Valley, India, eastern China, Indonesia, and the Philippines.
Climate change will push animals into cooler areas where their first encounters with other species will greatly increase the risk of new viruses infecting humans, researchers warned Thursday.
There are currently at least 10,000 viruses “silently circulating” among wild mammals that have the ability to cross over to humans, mostly deep in tropical forests.
As rising temperatures force these mammals out of their native habitats, they will encounter other species for the first time, creating at least 15,000 new cases of viruses jumping between animals by 2070, according to a study published in the journal Nature. .
“We have demonstrated a novel and potentially devastating mechanism for disease emergence that could threaten the health of animal populations in the future, which will also likely have ramifications for our health,” said study co-author Gregory Albery, a disease ecologist. in Georgetown. University.
“This work gives us more incontrovertible evidence that the coming decades will not only be hotter, but sicker,” Albery said.
The five-year study looked at 3,139 mammalian species, modeled how their movements would change under a variety of global warming scenarios, and then looked at how viral transmission would be affected.
The researchers found that new contacts between different mammals would indeed double, with the first encounters occurring all over the world, but particularly concentrated in tropical Africa and Southeast Asia.
The threat of bats
Global warming will also cause those first contacts to occur in more densely populated areas, where people “are likely to be vulnerable, and some viruses will be able to spread globally from any of these population centers,” according to the research.
Potential hotspots include the Sahel, the Ethiopian Highlands and Rift Valley, India, eastern China, Indonesia, the Philippines and some European population centers, the study found.
The research was completed just weeks before the start of the coronavirus pandemic, but it emphasized the unique threat posed by bats, in which COVID-19 is thought to have first emerged. As the only mammal that can fly, bats can travel far greater distances than their land-based brethren, spreading disease as they go.
Bats are thought to be already on the move, and the study found that they accounted for the vast majority of potential first encounters with other mammals, mostly in Southeast Asia.
Even if the world massively and rapidly reduces its greenhouse gas emissions, a scenario that still seems far off, it might not help with this problem.
The model showed that milder climate change scenarios could lead to more interspecies transmission than worst case scenarios, because slower warming gives animals more time to travel.
The researchers also tried to find out when the first interspecies encounters might begin to occur, hoping it would be later this century.
But “surprisingly” their projections found that most first contacts would be between 2011 and 2040, rising steadily from there.
“This is happening. It cannot be prevented even under the best climate change scenarios, and we must implement measures to build health infrastructure to protect animal and human populations,” Albery said.
The researchers stressed that while they had focused on mammals, other animals could harbor zoonotic viruses, the name for viruses that jump from animals to humans.
They called for more research into the threat posed by birds, amphibians and even marine mammals, as melting sea ice allows them to mingle more.
Study co-author Colin Carlson, a global change biologist also at Georgetown, said climate change is “creating countless hot spots of future zoonotic risk, or current zoonotic risk, right in our backyard.”
“We have to recognize that climate change is going to be the main driver of disease emergence,” Carlson said, “and we have to build health systems that are prepared for that.”