According to a research published on Thursday in the journal Nature, climate change would cause millions of viruses to spread from one animal species to another during the next 50 years, according to the study. According to the researchers, the reshuffling of viruses among animals may raise the likelihood that one of them would infect people and spark a new pandemic.
Since the beginning of time, scientists have cautioned that global warming may raise the burden of illness. It is believed that malaria would spread when the insects that transmit it extend their range into warmer climates, as is the case with dengue fever. Climate change, on the other hand, has the potential to bring in totally new illnesses by enabling infections to spread to new host species.
Dr. Carlson and his colleagues developed a computer model of possible spillovers in a warming world in order to better understand how that sharing would take place. For this first step, the researchers forecasted how thousands of animals would move their distributions as the climate changes between now and the year 2070.
Because of the rising temperatures, it is projected that many species would migrate away from the scorching Equator in search of more pleasant environments. Others may choose to climb up the slopes of hills and mountains in search of cooler heights to escape the heat. When viruses from various species come into contact for the first time, it is possible that the viruses may infect new hosts.
In order to determine the likelihood of a novel infection being successful, the researchers started by compiling a database of viruses and the mammalian hosts that they infected. It has been discovered that certain viruses are present in more than one species of animal, indicating that they must have crossed the species barrier at some time in the distant past.
The researchers created a model that could predict whether or not two host species were infected by the same virus by using a computer approach known as machine learning.
The researchers discovered that the greater the geographic overlap between two species, the greater the likelihood that they would share a virus. This is because the hosts were more likely to come into contact with one another, providing their viruses with more opportunity to spread among them.
Dr. Carlson and his colleagues were able to develop predictions based on their results about what might happen if mammal species came together for the first time in a hotter planet.
The researchers predicted that more than 4,000 cases of viral transmission from one species to another would occur among the 3,139 species they analysed in total. In certain circumstances, just a single virus will make the transition. The models, on the other hand, anticipated that numerous viruses carried by one species will spread to the other species in the future.
No specific viruses were identified by the researchers as being capable of moving across different animals. What counts, they reasoned, is the sheer magnitude of what is about to take place.
Despite the fact that she was not engaged in the study, Rachel Baker, a disease ecologist at Princeton University, stated that the research was an essential step forward in understanding how climate change would influence the world’s most lethal viruses. Previous research has concentrated on a specific virus rather than surveying the whole planet.
It is possible that these discoveries are especially concerning for human beings. In the process of spreading to new host species, viruses develop — and they might possibly mutate in ways that make them more likely to infect humans. Prior to infecting humans in 2002, the coronavirus that caused SARS in China began in horseshoe bats and then spread to another species — perhaps raccoon dogs sold in Chinese animal markets — before spreading to humans.
Researchers discovered another reason to predict new human epidemics when they looked at where animals would wind up in 2070: they won’t be flocking to wildlife refuges, as they had previously thought. As Dr. Carlson said, “It turns out that they are all the sites where we’ve established cities.”
Doctor Christine Johnson, an epidemiologist at the University of California, Davis who was not part in the research, expressed concern that such a wide model would miss subtleties that might have a significant influence on specific viruses. To better understand the effects of climate on species migrations and disease transmission risk, she believes that “locally grounded field investigations” are required.
Climate-related spillovers may begin far before the year 2070. After all, the earth has already warmed by 1.1 degrees Celsius compared to the 19th century. The researchers discovered in their computer model that there has already been enough temperature change to for viruses to mingle, albeit their model does not allow them to identify specific viruses that have made the trip to the other side of the planet.