CAMBRIDGE, United Kingdom — Climate change may be to blame for the emergence and spread of the Covid-19 pandemic, according to a new study.
Global greenhouse gas emissions have made southern China a hotspot for the bats that were responsible for carrying the virus. There have been 104 million cases of Covid-19 in the world, with 2.27 million deaths.
Large scale changes in the vegetation of the forest habitat favored by bats have created a suitable environment for many bat species. The world’s bat population carries around 3,000 different types of coronavirus, with each bat species harboring an average of 2.7 coronaviruses — most without showing symptoms. An increase in the number of bat species in a particular region, driven by climate change, may increase the likelihood that a coronavirus harmful to humans is present, transmitted, or evolves there, according to researchers at the University of Cambridge.
From studying the type of vegetation in the southern Chinese Yunnan province, and adjacent regions in Myanmar and Laos, the authors report increases in temperature, sunlight, and atmospheric carbon dioxide over the past century. To get their results, they created a map of the world’s vegetation as it was a century ago, using records of temperature, precipitation, and cloud cover. Then they used information on the vegetation requirements of the world’s bat species to work out the global distribution of each species in the early 1900s.
Comparing this to current distributions allowed them to see how bat “species richness,” the number of different species, has changed across the globe over the last century due to climate change.
“Climate change over the last century has made the habitat in the southern Chinese Yunnan province suitable for more bat species,” says Dr Robert Beyer, a researcher at 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. 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,” he continues, “but most likely allowed for new interactions between animals and viruses, causing more harmful viruses to be transmitted or evolve.”
The forest is also home to pangolins, which are believed to have acted as intermediate hosts to SARS-CoV-2, the virus that causes Covid-19. The virus is likely to have jumped from bats to these animals, which were then sold at a wildlife market in Wuhan, where the initial human outbreak occurred.
“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,” says co-author Andrea Manica, a professor at Cambridge.
“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,” says Camilo Mora, a professor at the University of Hawai’i at Manoa, who initiated the project.
The study is published in the journal Science of the Total Environment.
SWNS writer Joe Morgan contributed to this report.