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PICTURE: Estimated increase in local numbers of bat species due to changes in their geographic areas due to climate change since 1901. The enlarged area probably represents the spatial … More CREDIT: DR. ROBERT BEYER
The last century’s global greenhouse gas emissions have made southern China a hotspot for bat-borne coronavirus by spurring the growth of the bat-favored forest habitat.
A new study published today in the journal Science of the Total Environment provides the first evidence of a mechanism by which climate change may have played a direct role in causing SARS-CoV-2, the virus that causes the COVID-19 pandemic.
The study revealed major changes in vegetation types in southern China’s Yunnan Province and the neighboring regions of Myanmar and Laos over the past century. Climate changes such as temperature rise, sunlight and atmospheric carbon dioxide, which affect the growth of plants and trees, have changed the natural habitats from tropical scrubland to tropical savannah and deciduous forest. This created a suitable environment for many bat species, most of which live in forests.
The number of coronaviruses in an area is closely related to the number of different bat species present. The study found that over the past century another 40 bat species have moved to southern China’s Yunnan Province and are home to around 100 more species of bat-borne coronavirus. This “global hotspot” is the region where genetic data suggests that SARS-CoV-2 may have occurred.
“Climate change over the past century has made the habitat in southern China’s Yunnan Province suitable for more bat species,” said Dr. Robert Beyer, a researcher at the University of Cambridge’s Zoological Institute and first author of the study, who recently conducted a European research grant at the Potsdam Institute for Climate Impact Research in Germany.
He added, “Understanding how the global distribution of bat species has changed as a result of climate change can be an important step in reconstructing the origin of the COVID-19 outbreak.”
To get their results, the researchers created a map of the world’s vegetation as it was a century ago, using records of temperature, precipitation, and cloud cover. They then used information about the vegetation requirements of the world’s bat species to determine the global distribution of each species in the early 1900s. By comparing them with the current distributions, they were able to see how the biodiversity of bats, the number of different species, has changed worldwide in the last century due to climate change.
“As climate change changed habitats, species left some areas and moved to others – taking their viruses with them. Not only did this change the regions where viruses are present, it most likely enabled new interactions between animals and viruses, thereby transmitting or developing more damaging viruses, ”Beyer said.
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 with no symptoms. An increase in the number of bat species in a given region due to climate change can increase the likelihood that a coronavirus harmful to humans is present, transmitted, or developed there.
Most bat-borne coronaviruses cannot jump into humans. However, it is very likely that several coronaviruses known to infect humans have originated from bats, including three that can lead to human death: MERS-CoV (Middle East Respiratory Syndrome) and CoV-1 and CoV -2 with severe acute respiratory syndrome (SARS).
The region, identified in the study as a hotspot for a climate-induced increase in bat species richness, is also home to pangolins, which are believed to act as intermediate hosts for SARS-CoV-2. The virus likely jumped onto these animals from bats, which were then sold at a wildlife market in Wuhan – where the first human outbreak occurred.
The researchers echo calls from previous studies urging policy makers to recognize the role of climate change in viral disease outbreaks and to address climate change through COVID-19 economic recovery programs.
“The COVID-19 pandemic has caused enormous social and economic damage. Governments must seize the opportunity to reduce the health risks posed by infectious diseases by taking decisive action to curb climate change, ”said Professor Andrea Manica of the Cambridge University Institute of Zoology, who was involved in the study.
“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,” added Professor Camilo Mora of the University of Hawaii at Manoa, who initiated the project.
Researchers stressed the need to limit the expansion of urban areas, farmland and hunting areas to natural habitats in order to reduce contact between humans and disease-causing animals.
The study showed that climate change over the past century has also led to an increase in the number of bat species in regions around Central Africa and to scattered patches in Central and South America.
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From EurekAlert!
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