Zoonotic spillover events—where animal pathogens jump to humans—are expected to increase in the future due to climate and land use change, shifting the ranges of animal carriers. This will not only bring humans in closer contact with wildlife, but also lead to new opportunities for viral sharing among wild animals.
To explore the potential for increased transmission risk, researchers combined a mammal-viral network with species distribution models for more than 3,000 mammalian species based on GBIF-mediated occurrences and climate and land-use change scenarios for the year 2070.
Assuming that species are able to shift their ranges at the rate of global change, the study predicted that 99 per cent of mammals will overlap with at least one new species, permitting over 300,000 first encounters, effectively doubling the potential species contact from baseline. These encounters are predicted to lead to more than 15,000 new viral sharing events.
When taking into account the limited dispersal ability of flightless species, the number of first encounters and sharing events were reduced to about a third. The majority of transmission events were predicted to occur in southeast Asia, with bats accounting for nearly 90 per cent of first encounter cases.
Notably, the analysis predicts that the most optimistic scenario of climate change will lead to transmission risk at least as high as the most pessimistic one, and perhaps even higher, suggesting that greenhouse gas mitigation alone will not prevent increased viral sharing.
The authors recommend increased monitoring of not only viral spillover, but also transmission among wildlife species in order to improve the ability to respond timely to future zoonotic threats.