If last year’s climate change fueled megafires and the global pandemic has taught us something, it’s how interconnected we are all with each other and our environment. Now, we have some early indications that both climate change and the cause of the pandemic can also be intertwined – with bats.
Bats have a notorious ability to live with viruses that destroy other animals. While their strong immune system has been a blessing to them – allowing these aerial mammals to thrive around the world – it is a curse to the rest of us because they carry these viruses with them wherever they go.
Now, a new study has found that as the climate has warmed over the past century, rising sunlight, carbon dioxide and changes in rainfall have turned tropical shrubs in southern China into savannas and forests – the main habitat for bats. And over 40 new species of bats have moved.
“Understanding how the global bat species distribution has changed as a result of climate change may be an important step in reconstructing the origin of the COVID-19 outbreak,” said Cambridge University zoologist Robert Beyer.
To investigate this, Beyer and colleagues used data on world vegetation, temperature, precipitation, cloud cover, and vegetation requirements of bat species in the world to construct a map of their distribution in the early 1900s. working with current species distributions.
“As climate change changed habitats, species left some areas and moved to others – taking their viruses with them,” Beyer explained. “This has not only altered the regions where viruses are present, but most likely has allowed new interactions between animals and viruses, leading to the transmission or evolution of more harmful viruses.”
Changing the global bat distribution in 1901. (Beyer et al., 2021)
Three out of four infectious diseases emerging in humans are zoonotic diseases – they come from animals. Coronaviruses also make up more than a third of all bat viruses sequenced. The building blocks of the 2002 SARS pandemic were found in bats in a single cave, and now their bodies are the first suspects to have created beer from SARS-CoV-2 precursors.
Among them, the 40 relatively recent species of migratory bats in China’s Yunnan province carry more than 100 types of coronaviruses. Genetic evidence suggests that the ancestor SARS-CoV-2 came from the same region.
Most of these coronaviruses cannot infect us. And now, some bat species are mistakenly hunted for other species that have unintentionally wreaked havoc on us, even though these animals play a crucial role in our ecosystems. At least 500 species of plants depend on the pollination of bats (such as bananas, mangoes and agave), other plants depend on their poop, and some species keep insects under control (including boring mosquitoes, which spread disease) by devouring them.
But our relentless going on and on to the remaining natural habitats, through processes such as deforestation, which also causes climate change, increases our interactions between these animals and therefore our chances of encountering their viruses. Degraded habitats stress and weaken the immune system of the animals inside them, giving more chances for viruses to move into something that can jump over species barriers.
“Among the endangered wildlife species, those with population declines due to exploitation and habitat loss have shared several 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 are needed based on different vegetation and using different models to confirm their findings. Other variables that may have an impact on bat distribution, such as invasive species and pollution, also need to be investigated.
And, although the correlation is not equal to causality, a growing body of research suggests that climate change is a determining factor in pathogens infecting new hosts. We even have examples in which historical global climate change has been associated with environmental disturbances that have led to the emergence of infectious diseases.
“The fact that climate change may accelerate the transmission of wildlife pathogens should be an urgent wake-up call to reduce global emissions,” said biogeographer Camilo Mora of the University of Hawai’i, Manoa.
To reduce these risks, Beyer and colleagues strongly recommend the introduction of measures to limit human-animal interactions, including the imposition of strong regulations on wildlife hunting and trade, the discouragement of wildlife-dependent dietary and medicinal habits, and the setting of strict standards. animal welfare on farms, markets and vehicle transport. To do this, we must take into account the socio-economic needs that drive these practices that they note in their paper.
It is also crucial to protect natural habitats to maintain healthy species, a measure that can also help mitigate climate change.
“Given the high possibility of our analysis that global greenhouse gas emissions could have been a contributing factor to the SARS-CoV-1 and SARS-CoV-2 outbreaks, we echo calls for decisive mitigation of change including as part of COVID-19 economic recovery programs, “the team urges.
This research was published in Total environmental science.