Over the last century, global greenhouse gas emissions have made southern China a hotspot for bat-borne coronaviruses by driving the growth of forest habitats favored by bats.
Human-caused climate change has been blamed for having a widespread negative impact on public health issues, including respiratory disease, cardiovascular diseases, diabetes, and skin cancer in previous research wherein global warming, ultraviolet radiation, temperature changes, increased particulate matters, and heatwaves were described to be direct modulating factors (Witt, Schubert, et al. 2015, Tibuakuu, Michos, et al. 2018, Cuschieri and Calleja Agius 2020, Parker 2021).
The interconnection between climate change and malnutrition or water-borne disease has been a global research subject in the recent past (Walker 2018, Lieber, Chin-Hong, et al. 2020).
In one of the latest research, and for the first time, the concurrent global pandemic has been linked with climate change, as well. The full story was published in the journal Science of the Total Environment on 5th February 2021(Beyer, Manica, et al. 2021) and became global headlines.
In the study, the researchers first acknowledged that the disease COVID-19 is rooted in some bat species. Later the researchers discovered that climate change had shifted the global distribution of bats. Also, the researchers demonstrated that the number of coronaviruses present in an area is strongly correlated with an increased number of bat species in that particular area.
Climate Change Altered the Habitats
According to the paper, several climate change modulators such as greenhouse gas emissions, warmer temperatures, more sunlight, and increased atmospheric carbon dioxide not only changed the growth of trees and plants in Yunnan province and adjacent areas such as Myanmar and Laos but also created sustainable environments for many bat species that lives predominately in forests.
“As climate change altered habitats, species left some areas and moved into others – taking their viruses with them,” Robert Beyer, a researcher in the University of Cambridge’s Department of Zoology and lead author of the study, said in a news release. “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” (Garget 2021).
To get the results, the authors first collected temperature, precipitation, and cloud cover records from the early 1900s (1901-1930) and 1990 – 2019. Second, based on the climate data, they estimated the global distribution of natural vegetation in both the early 1900s and as it is now. Third, they evaluated vegetation requirements for bat species to grow and finally compared the distribution of bat species of the early 1900s with that of the present distribution.
40 Bat Species Moved into Southern China
The study found that as many as 40 bat species moved into the southern Chinese Yunnan province in the 1900s, harboring around 100 more types of bat-borne coronavirus.
Genetic data suggest this ‘global hotspot’ is the region where SARS-CoV-2, the virus that causes COVID-19, may have arisen. The region identified by the study as a hotspot for a climate-driven increase in bat species richness is also home to pangolins, which are suggested to have acted as intermediate hosts to SARS-CoV-2.
Though the source of the virus that causes COVID-19 remains undecided, scientists widely believe some species of bats in southern china first passed the virus to pangolins. Next, the animals were sold at a market in Wuhan, and then the virus infected a person, who was declared the first victim of coronavirus on 31st December 2019.
The study showed that climate change has also increased the number of bat species in regions around Central Africa and scattered patches in Central and South America over the last century.
The authors acknowledge some limitations in the methods used in the study to simulate vegetation maps with bat ranges and say more work needs to be done before making a definitive connection between climate change and COVID-19.