Climate change may have been caused by “highly involved” people in coronavirus pandemic. That is the conclusion of a new study that examined how climate change has changed the forests of Southeast Asia, resulting in an explosion of bat species in the region.
The researchers found that as a result of changes in vegetation over the past 100 years, an additional 40 species of bats have migrated into the area, carrying 100 more species of coronaviruses by bat. orra. Bats are known to be carriers of coronaviruses, with different species carrying thousands of different species. Many scientists believe that the virus started the COVID-19 pandemic worldwide originally in bats in the Yunnan region of southern China or nearby areas before crossing human tracks.
These findings have worried scientists about the likelihood that future climate change will make pandemics more likely.
“If bats carrying around 100 coronaviruses expanded into a new area as a result of climate change, this would likely increase, rather than decrease, the chance of a harmful coronavirus people present, moved, or growing in this field, ”explains Dr Robert Beyer, lead author of the study and researcher at Cambridge University.
Ng Han Guan / AP
The researchers used climate charts to create a map of the world’s vegetation as it was a hundred years ago. Using knowledge of the type of vegetation required by different bat species, they determined the global distribution of each species in the early 1900s.
They then compared this with normal bat numbers. Their findings show that the richness of bat species – the number of different bat species found in a particular region – has outperformed this pocket of Southeast Asia more than anywhere else on Earth.
The image below, from the study, shows how the forests of southern China, Myanmar and Laos have changed over the past century, enhancing bat-friendly habitat and allowing multiply more species. This particular bullseye across the region shows an increase in the species richness of bats. (The study does not consider general population sizes, only the diversity of bat species in the area.)
Dr. Robert Beyer
According to the authors, climate changes such as rising temperatures, sunlight and carbon dioxide, which affect the growth of plants and trees, have reversed the movement of vegetation in southern China, which turning tropical shrubland into a tropical savannah and deciduous forest. This type of forest, the authors maintain, is more suitable for bat species.
The study calls this region in Southeast Asia a “major global destination” for bat species and identifies genetic data suggesting the origin of SARS-CoV-2, the virus that causes COVID-19, in this area.
This, the authors say, provides the first evidence of a way in which climate change may have played a direct part in the spread of the virus.
“We conclude that, over the past century, climate change has led to a significant increase in the number of bat species in the area where SARS-CoV-2 appears to have originated,” Beyer said. . “This increase suggests a possible approach to how climate change would have been part of the origins of the pandemic. ”
There was a team of researchers from the World Health Organization finally allowed into Wuhan, China, in January to investigate the origins of the uprising, first reported in that city a little over a year ago. A key theory among scientists is that the virus came from bats before it spread to humans, possibly through the host of such an animal. pangolins. Some of the first cases were related to a wildlife market in Wuhan. But as of now, this is just theory, and researchers are just starting to study formally where the pandemic came from.
The study Rick Ostfeld, a disease ecology expert from the Cary Institute for Ecosystem Studies in Millbrook, New York, finds the research strong, although he disagrees with his conclusions. He says it is not surprising that climate change has been discovered on forests and altered bat communities. He also agrees with the authors of the study that the movement of animals can help spread viruses.
“The movement of animal communities around an area can have a significant impact on the spread of disease by exposing animal hosts to new pathogens,” he said.
But he is cautious about coming to conclusions beyond that.
“The association with the exposure to coronaviruses is highly speculative and seems unlikely,” Ostfeld said.
“What the study seems to be wrong with is the assumption that the increased diversity of bats (which they post) leads to an increased risk of bat bat virus spreading to humans. this is not true, “he said. “Most bats are harmless to humans – they don’t harbor viruses that could make us sick. So adding more of these species doesn’t increase risk.”
Kate Jones, who is a professor of ecology and biodiversity at University College London, is also very cautious. She said, “Climate change certainly has a role to play in changing species distributions to increase ecological risk. However, spill risk is a complex interplay of not only ecological risk. but the manifestation and vulnerability of men. “
Beyer agrees that there is a “reasonably good warning” when it comes to linking climate change directly to the pandemic because, as he explains, assessing the extent to which change adding to any level between a bat carrying the virus and a person getting a disease will take a lot more work. Specifically, he says, this involves the use of epidemiological models that analyze the interactions of different species and viruses over space and time.
While it is widely understood that human growth is exponential, and how we take advantage of the natural world destroying forests and expanding the animal trade, is increases the risk of infectious pathogens easier to make the leap from animals to humans, it was less clear to what extent climate change factors included.
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However, over the past century, due to human-induced climate change, many ecosystems have warmed – sometimes at several levels – and rainfall patterns have shifted, with some areas becoming smaller and others getting more. These ecosystem changes are moving the habitat of many species, bringing more species into contact with each other, allowing viruses to spread more easily.
When asked about the links of climate to the spread of disease, most experts agree that there is an effect, but some say that human actions are just deforestation, development, or industrial-scale animal husbandry, a greater concern.
“It may turn out that an increase in human numbers, human movement and polluted natural environments through agricultural expansion has a more important role to play in understanding the SARS-CoV-2 spill process,” Jones explained.
Ostfeld said, “We can predict which wildlife species are most likely to carry pathogens that can make people sick. These are usually the ones that thrive when we cultivate. , residential developments and strip malls instead of natural habitat (such as forests and savannas). “
Beyer will not raise an issue with these assessments. “We fully agree that the expansion of urban areas, farmland, and hunting grounds to natural habitats is a key driver for the spread of zoonotic diseases – these are the main contributors to the lives of animals and humans. pathogens involved in the first place, “he said.
But with the findings of his research on how climate reshaped the region, Beyer feels climate change can be an important driver.
“Climate change can drive where these animals occur; in other words, climate change can move pathogens closer to humans. It can also shift a species that carries a virus into a habitat. another species that the virus can jump to – a step that may not have happened without climate change, which can have a significant long – term effect on where the virus can go.
Beyer also sees climate links more than just an increase in bat species. “In some cases, higher temperatures can increase the viral load in species, which can make the virus more likely to be transmitted,” he said. “And: Higher temperatures can heat up the tolerance of viruses, which can increase disease levels because one of our key immune systems for infectious diseases is an increase in our body temperature (fever).”
While there is little warning in the scientific community about the specific impact of climate change on the pandemic coronavirus, there is widespread agreement that, in the future, climate change will continue to grow as a result of infectious disease. and pandemics.
“Climate change will shift the geographic distributions of pathogen-carrying species in such a way that they interact with species that have not previously overtaken them,” said Beyer. These new operations provide dangerous opportunities for viruses to spread and develop. ”
“Climate change is certainly an important driver in the incidence and spread of disease. It can increase transmission in a number of ways,” Ostfeld said. “So, yes, climate change is definitely worrying me as a driver of future pandemics.”