Scientists think that the COVID-19 coronavirus currently plaguing the world likely originated in bats. But bats have been around forever, so why an outbreak now? A study published in the journal ‘Science of The Total Environment’ lays the blame on climate change. According to the study, climate change has caused a shift in the global distribution of bats. “Most species require particular climatic and environmental conditions to be present in an area in order for it to be a suitable habitat,” explained study lead author Dr Robert Beyer of the University of Cambridge and the Potsdam Institute for Climate Impact Research in Germany in an interview posted on the ‘News Medical Life Sciences’ website. “As climate change alters these conditions, the geographic ranges of species begin to shift. This can force species to disappear from some areas while allowing them to expand in others,” stated Dr Beyer, whose research was supported by the EU-funded LocalAdaptation project. The research team identified the areas estimated to have seen the largest climate change-driven increase in bat species. These include regions around Central Africa, scattered areas in Central and South America, and a large area encompassing southern China’s Yunnan province, Myanmar and Laos. The latter hotspot is where SARS-CoV-2 and SARS-CoV-1 – the virus responsible for the 2003 SARS global outbreak – are believed to have originated.
The role of climate change in disease outbreaks
When species’ geographic ranges shift due to climate change, the viruses they carry come closer to humans directly or might jump to other species in invaded habitats. Climate change also affects the spread of viruses through higher temperatures that increase the viral load in some species, consequently increasing the chances that a virus will be transmitted. “Higher air temperatures can also increase the tolerance of viruses to heat, which in turn can increase infection rates, given that one of the primary defense systems against infectious diseases is to raise our body temperature,” observed Dr Beyer. In their study of the region around the southern Yunnan province, the researchers found that climate change led to the region’s large-scale shift from tropical scrublands to tropical savannas and deciduous woodland over the past 100 years. This created a suitable environment for many bat species, resulting in an estimated increase of around 40 bat species in the region. “Given that each bat species carries on average 2.7 coronaviruses, this corresponds to an estimated increase in the order of 100 bat-borne coronaviruses,” noted Dr Beyer. “This increase in the number of bat species likely created new opportunities for cross-species transmissions of viruses, which may have increased the likelihood of an eventual spillover to humans.” The study supported by LocalAdaptation (Detecting Local Adaptation with Climate-Informed Spatial Genetic Models) highlights the possible link between climate change and the emergence of the two SARS-CoV viruses. Dr Beyer concluded: “Our analysis is a first step towards assessing the possible contribution of climate change in the pandemic, not the final one. With this said, we certainly know that climate change is altering the global distribution of pathogen-carrying wildlife significantly and that these shifts in species’ ranges can play a critical role in the transmission and evolution of harmful viruses. It is therefore important to consider the impact of climate change also in the context of emerging infectious diseases and global public health.” For more information, please see: LocalAdaptation project
LocalAdaptation, COVID-19, coronavirus, climate change, bats