There will be at least 15,000 instances of viruses leaping between species over the next 50 years, with the climate crisis helping fuel a “potentially devastating” spread of disease that will imperil animals and people and risk further pandemics, researchers have warned.
Many animal species will need to relocate as the planet heats. They will bring their parasites and pathogens with them, causing them to spread between species that haven’t interacted before. This will heighten the risk of what is called “zoonotic spillover,” where viruses transfer from animals to people, potentially triggering another pandemic of the magnitude of Covid-19.
“As the world changes, the face of disease will change too,” said Gregory Albery, an expert in disease ecology at Georgetown University and co-author of the paper, Published in Nature. “This work provides more incontrovertible evidence that the coming decades will not only be hotter, but sicker.”
“We have demonstrated a novel and potentially devastating mechanism for disease emergence that could threaten the health of animals in the future and will likely have ramifications for us, too.”
Albery said that climate change is “shaking ecosystems to their core” and causing interactions between species that are already likely to be spreading viruses. He said that even drastic action to address global heating now won’t be enough to halt the risk of spillover events. “This is happing; it’s not preventable even in the best-case climate change scenarios, and we need to put measures in place to build health infrastructure to protect animal and human populations,” he said.
The research paper states that at least 10,000 types of viruses capable of infecting humans are circulating “silently” in wild animal populations. Crossover infections like these were rare until recently. However, more habitat has been lost to agriculture and urban growth. More people have come in contact with infected animals.
Climate change is causing this problem by helping to spread disease between species that had never met before. The study predicted the geographic range shifts in 3,139 mammal species as a result of climatic and landscape changes up to 2070. It also found that there will be at most 15,000 cross-species transmission events for one or more viruses even at a low level of global warming.
Because of their ability to travel long distances, bats will be responsible most of this disease spreading. The Covid pandemic was likely started by an infected bat in Wuhan, China. Previous research has estimated there are about 3,200 strains of coronaviruses already moving among bat populations.
New research warns that climate-driven diseases are not a threat in the future. “Surprisingly, we find that this ecological transition may already be under way, and holding warming under 2C within the century will not reduce future viral sharing,” the paper states.
High-elevation areas in Africa, Asia and the Middle East are where most of the disease risk lies. However, it is difficult to monitor the progress of some viruses.
“There is this monumental and mostly unobserved change happening within ecosystems,” said Colin Carlson, another co-author. “We aren’t keeping an eye on them and it makes pandemic risk everyone’s problem. Climate change is creating numerous hotspots of zoonotic risk right here in our backyard. We have to build health systems that are ready for that.”
Experts who weren’t involved in the research stated that the study highlighted an urgent need to improve processes and prevent future pandemics as well as phase out fossil fuels which are causing the climate crisis.
“The findings underscore that we must, absolutely must, prevent pathogen spillover,” said Aaron Bernstein, interim director of the center for climate, health, and the global environment at Harvard University. “Vaccines, drugs and tests are essential but without major investments in primary pandemic prevention, namely habitat conservation, strictly regulating wildlife trade, and improved livestock biosecurity, as examples, we will find ourselves in a world where only the rich are able to endure ever more likely infectious disease outbreaks.”
Peter Daszak, president of EcoHealth Alliance, a nonprofit that works on pandemic prevention, said that while human interference in landscapes has been understood as a disease risk for a while, the new research represents a “critical step forward” in the understanding of how climate change will fuel the spread of viruses.
“What’s even more concerning is that we may already be in this process—something I didn’t expect and a real wake-up call for public health,” he said. “In fact, if you think about the likely impacts of climate change, if pandemic diseases are one of them, we’re talking trillions of dollars of potential impact.
“This hidden cost of climate change is finally illuminated, and the vision this paper shows us is a very ugly future for wildlife and for people.”