Warming planet can find 15,000 new cros8k8 app log ins-species virus transmissions by 2070

The effect of climate change on global weather systems is well known, but what is not well known is the impact it is having on the global transmission of viruses from animals to humans.

With forecasts the planet will breach the 1.5 degrees Celsius global heating limit within the next five years, new research shows warming of the planet could see thousands of new viruses spreading among many kinds of animals within the next 50 years as those animals migrate to new areas.

The risk is highest in areas of high human population density, such as tropical Africa and Southeast Asia, according to a study by scientists from South Africa and the United States.

The scientists say we could see at least 15,000 new viral transmissions between species by 2070 based on a model where the planet warms by 2 C.

The findings were published in the scientific journal Nature in late April, in a paper entitled "Climate change increases cross-species viral transmission risk".

The researchers said not all viruses will spread to humans or lead to widespread pandemics like COVID-19. However, the study suggests the high number of cross-species viruses will increase the risk of spread to humans. COVID-19, which grew into a global pandemic, is thought to have originated in bats.

"As the climate warms, many animal species will be driven to new environments, taking their parasites and pathogens with them," the study found.

"These geographical shifts may facilitate viral sharing between species that previously had no interactions, which may in turn assist zoonotic spillover – the transmission of pathogens from wild animals to humans."

Lead author of the paper, Colin Carlson, assistant research professor with the Center for Global Health Science and Security at Georgetown University Medical Center in Washington DC, said: "We don't talk about climate a lot in the context of diseases than can spread from animals to people."

In a recent interview with Georgetown University Medical Center's EurekAlert magazine, he said the study was the first comprehensive assessment of how climate change will restructure the global mammalian virome.

The mammalian virome is constituted of viruses that infect host cells, virus-derived elements in our chromosomes, and viruses that infect the broad array of other types of organisms that inhabit humans.

Carlson said the study focused on geographic range shifts – the journeys that species will undertake as they follow their habitats into new areas. As they encounter other mammals for the first time, the study projects they will share thousands of viruses.

"The closest analogy is actually the risks we see in the wildlife trade," Carlson said.

"We worry about markets because bringing unhealthy animals together in unnatural combinations creates opportunities for this stepwise process of emergence – like how SARS jumped from bats to civets, then civets to people. But markets aren't special anymore; in a changing climate, that kind of process will be the reality in nature just about everywhere."

"At every step," said Carlson, "our simulations have taken us by surprise. We've spent years double-checking those results, with different data and different assumptions, but the models always lead us to these conclusions. It's a really stunning example of just how well we can, actually, predict the future if we try."

The scientists suggest that climate change will become the biggest upstream risk factor for disease emergence – exceeding higher-profile issues like deforestation, wildlife trade, and industrial agriculture. The authors say the solution is to pair wildlife disease surveillance with real-time studies of environmental change.

With warming already occurring, climate-driven shifts in hotspots for species dispersal and viral evolution may already be underway, the scientists noted.

Targeting surveillance in future hotspots may help to identify infectious diseases jumping between species, the study concluded.

Associate Professor Linda Selvey from the School of Public Health at the University of Queensland said the findings "are consistent with the findings of other studies" and should be taken "very seriously".

"These 'spillover' events (between species) have been well documented as a mechanism of transmission of viruses present in another animal to humans," she said.

She cites examples such as the Hendra virus (flying fox to human via horses), Nipah virus (flying fox to human via pigs), Ebola virus (microbat to human via chimpanzees), SARS-CoV (microbat to humans via civet cats), SARS-CoV-2 (microbats to humans via an unknown intermediate host).

"The reason why flying foxes had more interactions with horses and pigs in the Nipah and Hendra virus examples is thought to be due to habitat destruction, bringing flying foxes in closer proximity to horses and pigs," Selvey said.

She said the study suggests that "as global average temperatures increase, so will these new interactions between species, and that these are most likely where there is already a lot of species diversity, such as in tropical Africa and Asia".