Climate change will lead to increased spread of viruses to humans, which could cause new pandemics

A major study recently published in the journal Nature (Carlson, Albery et al., “Climate change increases the risk of virus transmission across species“) concludes that ongoing climate change will greatly increase the risk of transmission to humans of viruses already present in animal populations, as has already happened with SARS-CoV-2 and others such as HIV and Ebola, collectively known as zoonoses (diseases). of animal origin).

This alarming finding is based on the development of a model by these researchers, which predicts how global warming is likely to cause displacement of a sample of more than 3,000 mammalian species over the next 50 years, assuming a probable increase of 2 degrees Celsius in global average temperature.

Geographically shifting eco-zones will force animals, plants and other organisms to adapt to their territorial distributions as the spatial boundaries of the habitats to which they are adapted change. This will involve the actual displacement of individuals or the gradual adjustment of intervals as some populations disappear and others placed in more favorable environments become more successful.

Due to a number of factors (eg topography, latitude, precipitation patterns) these changes will not only displace existing undisturbed eco-zones. Rather, the global changes will result in a “mixing and matching” of different environmental components, which will have the effect of bringing together species that were not previously very close to each other, creating adaptive constraints that are likely to favor some species over others. , leading to extinction. Overall, this will result in a significant decrease in the stability of ecosystems.

As a result, the possibility that viruses will not only spread between different populations of the same species once they have spread, but also between species, including to humans, will be increased.

It is estimated that 40,000 viruses infect mammals. Among them, 10,000 could potentially infect humans, but they are currently found only in animals. The model predicts that climate change will lead to about 300,000 “first encounters” between species that were not in contact before. It is estimated that the spread of viruses between species will be on the order of 15,000 times, including more than 4,000 times in mammals alone, during the period covered by the model.

This map visualizes predicted new viral sharing events near human population centers in Equatorial Africa, South China, India, and Southeast Asia in 2070. These events will increasingly overlap with hotspots intended for virus transmission between species in wildlife. (Photo courtesy of Colin Carlson / GUMC)

Furthermore, as new host species become infected, creating new selective environments for viruses, new variants can be expected to evolve, as is currently the case with SARS-CoV-2. Viral exchange between non-human species must also be expected to seriously affect wildlife populations with its own unforeseen consequences.

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