(CN) — Scientists revealed Friday that climate change may have been an important catalyst in the Covid-19 pandemic as ecosystem changes drove coronavirus-carrying bats into regions of southern China’s Yunnan province, Laos and Myanmar, possibly setting the stage for the outbreak.
The study detailing the findings was published in the journal Science of the Total Environment.
"Climate change over the last century has made the habitat in the southern Chinese Yunnan province suitable for more bat species," explained the paper’s lead author Robert Beyer, a researcher in the University of Cambridge's Department of Zoology in a statement. "Understanding how the global distribution of bat species has shifted as a result of climate change may be an important step in reconstructing the origin of the Covid-19 outbreak.”
Researchers developed a model to understand how climate change altered bat habitats over the last century. By tracing increases in temperature and sunlight as well as spikes in carbon dioxide levels, the study outlined complex large-scale changes in the region that transformed tropical shrubland into savanna and woodlands where bats thrive.
"As climate change altered habitats, species left some areas and moved into others — taking their viruses with them. This not only altered the regions where viruses are present, but most likely allowed for new interactions between animals and viruses, causing more harmful viruses to be transmitted or evolve," Beyer said.
The model does not take into account other variables like pollution, hunting and habitat destruction. Additional biological factors may contribute to the spread of diseases, the paper explains, “such as the effect of higher temperatures on the susceptibility of animal host species to pathogens.”
Still, understanding the movement of bats may be key to understanding the spread of Sars-Cov-2, a zoonotic virus that causes Covid-19 and began infecting humans in China in 2019.
Many researchers hypothesize the disease originated in bats, which are a common carrier of coronaviruses. Bats then infected pangolins or civets before the virus jumped to humans in a wet market in Wuhan, China.
Bats carry an estimated 3,000 different types of coronaviruses. Most coronaviruses do not infect humans, but several that do are often fatal, including the viruses that cause MERS and SARS.
The results from the Cambridge University model identify several hotspots around the world, including central Africa and South America where bat diversity increased alongside climate-driven changes to the ecosystem. The model also estimates 40 new species of bats moved into the Yunnan province in China over the last century.
“The number of coronaviruses that are present in an area is strongly correlated with local bat species richness,” the scientists explain in the paper. “An increase in local bat richness may therefore increase the probability that a coronavirus with potentially harmful properties for human life is present, transmitted, or evolves in the area.”
In identifying these habitats, the researchers hope to encourage local governments to protect these areas from hunting and trade, thus reducing the encounters of people with potential zoonotic diseases.
"The Covid-19 pandemic has caused tremendous social and economic damage. Governments must seize the opportunity to reduce health risks from infectious diseases by taking decisive action to mitigate climate change," said Andrea Manica at the University of Hawaii at Manoa in a statement. "The fact that climate change can accelerate the transmission of wildlife pathogens to humans should be an urgent wake-up call to reduce global emissions.”
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