When we think about climate change, we tend to consider its most direct effects, like severe weather and sea level increases. But some of the changes incurred by climate change introduce their own effects. Scientists warn that as the planet warms, permafrost around the world will thaw, reintroducing dangerous pathogens to the environment that have been dormant for millennia.
In a study published in PLOS Computational Biology, an international team of researchers share their investigation into the effects of climate change-induced permafrost melt. Using a computerized life simulation called Avida, they created mock environments in which ancient pathogens could be introduced. The researchers accounted for competition with modern “native” pathogens and potential hosts’ evolved resistance. (Some mockups also considered how certain hosts could have lost their resistance over time as pathogenic risk decreased.) The simulations allowed each revived pathogen to reproduce as it would in a natural environment.
On average, these simulations revealed ancient invading pathogens more persistent than 33.6% of native pathogens. In fact, 3.1% of invading pathogens became dominant in their new environments and persisted for hundreds of generations. About 1% of the 3.1% dominant invading pathogens behaved “unpredictably,” causing up to a third of their host species to die out and diversify in their environments. Meanwhile, only 5.4% of native pathogens—meaning the ones we see today—survived.
“The unprecedented rates of melting of glaciers and permafrost are now giving many types of ice-dormant microorganisms concrete opportunities to re-emerge,” the researchers write. “For the first time, we provide an extensive exploration of the ecological risk posed to modern ecological communities by these ‘time-traveling’ pathogens….We found that invading pathogens could often survive, evolve and…[cause] either substantial losses or gains in the total richness of free-living species.”
As acknowledged in the paper, Avida and other life simulations can only match the real world to a certain extent: For example, generations and evolutionary updates in Avida can’t be directly translated into a consistent measure of real time. Still, their theoretical experiment offers valuable (if concerning) insight into one of the many consequences of climate change. When ecosystems are already up against unprecedented environmental hazards, reintroducing ancient viruses, bacteria, and parasites could be catastrophic.
