If last year’s climate change fueled megafires and the global pandemic taught us something, then this is how we are all interconnected and our environment. Now we have some early tips that both climate change and the cause of the pandemic can also be intertwined – by bats.
Bats have a notorious ability to live with viruses that destroy other animals. Although their superpowered immune system has been a blessing to them – so that these mammals can thrive in the world around the world – it is a curse to the rest of us because they carry these viruses everywhere they go.
Now, a new study has found that the increase in sunlight, carbon dioxide and precipitation change in southern China’s tropical shrubbery to savannah and bushveld is the most important habitat for bats as the climate has warmed over the past century. And more than 40 new bat species have moved in.
“Understanding how the global distribution of bat species has shifted due to climate change could be an important step in reconstructing the origins of the COVID-19 outbreak,” said Cambridge University zoologist Robert Beyer. .
To investigate this, Beyer and colleagues used data on the world’s vegetation, temperature, precipitation, cloud cover, and the vegetation of the world’s bat species to compile a map of their distribution in the early 1900s. They then compare it to the distribution of species of today.
“As climate change has changed habitats, species have left some areas and moved into others and taken their viruses with them,” Beyer explained. “It has not only changed the regions where viruses occur, but probably also made possible new interactions between animals and viruses, causing more harmful viruses to be transmitted or developed.”
Change in global distribution of bats since 1901. (Beyer et al, 2021)
Three out of four emerging infectious diseases in humans are zoonotic diseases – they come from animals. And coronaviruses contain more than a third of all bat viruses. The building blocks of the 2002 SARS pandemic were found in bats from a single cave, and now their bodies are the biggest suspect in brewing the predecessors of SARS-CoV-2.
Among them, the 40 relatively recent migrating bat species to the Yunnan province in China carry more than 100 species of coronavirus. Genetic evidence suggests that the ancestor of SARS-CoV-2 is from the same region.
However, most of these coronaviruses cannot infect us. And now some species of bats are being wrongly persecuted for other species that we inadvertently destroy, even though these animals play an important role in our ecosystems. At least 500 plant species depend on bat pollination (such as bananas, mangoes and agave), other plants depend on their poop, and some species keep insects in check (including pesky, disease-spreading mosquitoes) by devouring them.
But our relentless march further and further into the remaining natural habitats through processes such as deforestation, which also drives climate change, increases our interaction between these animals and thus our chances of encountering their viruses. Demarcated habitats also emphasize and weaken the immune system of the animals within them, offering more chances for viruses to mutate into something that can jump over species barriers.
“Among endangered game species, those with population decline due to exploitation and habitat loss shared more viruses with humans,” a study found last year.
Beyer and the team warn that we do not yet know the exact origin of SARS-CoV-2, so their inferences are not yet conclusive and further studies based on different vegetation and the use of different models are needed to confirm their findings. Other variables that may affect the spread of bats, such as invasive species and pollution, should also be investigated.
And although correlation does not equate to causality, a growing body of research suggests that climate change is the cause of pathogens infecting new hosts. We even have examples where historical global climate change is accompanied by environmental disruptions that have led to emerging infectious diseases.
“The fact that climate change can accelerate the transmission of pathogens in the wild must be an urgent wake-up call to reduce global emissions,” said biogeographer Camilo Mora of the University of Hawaii, Manoa.
To reduce these risks, Beyer and colleagues strongly recommend that measures be taken to limit interactions between humans and wildlife, including the introduction of strong regulations on hunting and trafficking in wildlife, the discouragement of food-dependent nutritional and medicinal uses, and the establishment of strict animal welfare standards on farms, markets and transport vehicles. In order to do this, we need to take into account the socio-economic needs that these practices indicate in their paper.
It is also crucial that we protect natural habitats to keep species healthy, a measure that can also help mitigate climate change.
“Given the possibility raised by our analysis that global greenhouse gas emissions could be a contributing factor in the SARS-CoV-1 and SARS-CoV-2 outbreaks, we call for definite climate change, including as part of COVID-19 economic recovery programs, “the team insists.
This research was published in the Science of the total environment.