Climate Change Likely to Trigger the Possibility of the Next Pandemic

As continuous warming occurs in the Earth’s climate, scientists forecast wild animals will be compelled to shift their habitat, probably to areas with large human populations. This considerably increases the threat of a viral jump to humans that could result in the next pandemic.

Climate Change Likely to Trigger the Possibility of the Next Pandemic.
Novel viral-sharing events coincide with human population centers. In 2070, human population centers in equatorial Africa, south China, India, and Southeast Asia will overlap with projected hotspots of cross-species viral transmission in wildlife. Image Credit: Colin Carlson/GUMC.

This connection between climate change and viral transmission is elucidated by an international research team headed by researchers at Georgetown University.

The study was published on April 28th, 2022, in the journal Nature.

In their research, the investigators carried out the first complete analysis of how climate change will reorganize the global mammalian virome. The study stresses geographic range shifts including the journeys that species will tend to take as they relocate into new areas.

As they encounter other mammals for the first time, the study projects that they would be sharing thousands of viruses.

The researchers feel that such shifts will bring greater chances for viruses like coronaviruses or Ebola to arise in new areas, thereby making them harder to follow, and into new kinds of animals. This makes it easier for viruses to jump across a so-called “stepping stone” species into humans.

The closest analogy is actually the risks we see in the wildlife trade. 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.

Colin Carlson Ph.D., Study Lead Author and Assistant Research Professor, Center for Global Health Science and Security, Georgetown University Medical Center

A significant factor is that animal habitats will shift unevenly in the same places as human settlements to make new hotspots of spillover risk. The majority of this process might already be ongoing in the 1.2 degrees warmer world. Also, measures taken to decrease greenhouse gas emissions might not stop these events from taking place.

One more extra finding is the impact of increasing temperatures on bats, which accounts for most of the novel viral-sharing. Their potential to fly will enable them to travel long distances and share the majority of the viruses.

Due to the bat’s central role in viral emergence, the biggest impacts are projected in southeast Asia, known to be the global hotspot of bat diversity.

At every step 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.

Colin Carlson Ph.D., Study Lead Author and Assistant Research Professor, Center for Global Health Science and Security, Georgetown University Medical Center

The authors of the study state that the impacts on conservation and human health could be astonishing since viruses begin to jump between host species at unparalleled rates.

This mechanism adds yet another layer to how climate change will threaten human and animal health. It’s unclear exactly how these new viruses might affect the species involved, but it’s likely that many of them will translate to new conservation risks and fuel the emergence of novel outbreaks in humans,” stated the study’s co-lead author, Gregory Albery, Ph.D., a postdoctoral fellow in the Department of Biology in the Georgetown University College of Arts and Sciences.

Overall, the study indicates that climate change will become the largest upstream risk factor for the emergence of disease — surpassing higher-profile problems such as wildlife trade, deforestation and industrial agriculture. The authors feel that the solution is to match wildlife disease surveillance along with real-time studies of environmental change.

When a Brazilian free-tailed bat makes it all the way to Appalachia, we should be invested in knowing what viruses are tagging along. Trying to spot these host jumps in real-time is the only way we’ll be able to prevent this process from leading to more spillovers and more pandemics.

Colin Carlson PhD, Study Lead Author and Assistant Research Professor, Center for Global Health Science and Security, Georgetown University Medical Center

Carlson added, “We’re closer to predicting and preventing the next pandemic than ever,” says Carlson. “This is a big step towards prediction—now we have to start working on the harder half of the problem.”

The COVID-19 pandemic, and the previous spread of SARS, Ebola, and Zika, show how a virus jumping from animals to humans can have massive effects. To predict their jump to humans, we need to know about their spread among other animals,” stated Sam Scheiner, a program director with the US National Science Foundation (NSF), which financially supported the study.

Scheiner added, “This research shows how animal movements and interactions due to a warming climate might increase the number of viruses jumping between species.”

Additional authors of the study included collaborators from the University of Connecticut (Cory Merow), Pacific Lutheran University (Evan Eskew), the University of Cape Town (Christopher Trisos), and the EcoHealth Alliance (Noam Ross, Kevin Olival).

The authors have stated that they do not have any personal financial interests corresponding to the study.

The study outlined above has been financially supported in part by a National Science Foundation (NSF) Biology Integration Institutes (BII) grant (BII 2021909), to the Viral Emergence Research Initiative (Verena).

Co-founded by Carlson and Albery, Verena curates the biggest ecosystem of open data in viral ecology and develops tools to help forecast which animals host them, which viruses could tend to infect humans, and where they could arise one day.

NSF BII grants assistance to diverse and collaborative groups of scientists analyzing questions that cover various disciplines within and beyond biology.

Extra financial support was offered by the NSF grant DBI-1639145, the USAID Emerging Pandemic Threats PREDICT program, the Institut de Valorisation des Données, the National Socio-environmental Synthesis Center, and the Georgetown Environment Initiative.

Journal Reference:

Carlson, C. J., et al. (2022) Climate change increases cross-species viral transmission risk. Nature.

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