Cold facts: Flinders Uni study reveals threats posed by thawing ice

For a long time, the threat of ancient bacteria being released by thawing ice has been the stuff of science fiction movies – so how much of a risk is it really?

It reads like a science fiction movie – ancient germs trapped in the ice, released by climate change and infecting humans with unknown diseases.

The risk, however, is very real according to a new study involving Adelaide’s Flinders University.

While melting glaciers and permafrost risk the re-emergence of many types of dormant pathogens, the potential destruction to modern ecosystems posed by these microbes has been difficult to predict.

A new global study by Dr Giovanni Strona of the European Commission Joint Research Centre and Matthew Flinders Professor of Global Ecology Corey Bradshaw from Flinders University, published in the open-access journal PLOS Computational Biology, has calculated the ecological risks posed by the release of these unpredictable ancient microbes.

The researchers constructed simulated experiments where digital pathogens from the past invade communities of bacteria-like hosts. They compared the effects of the invading pathogens on the diversity of host bacteria to those in communities where no invasions occurred.

A Flinders University study has revealed the dangers of pathogens trapped in ice being released back into the world. Picture: Dr Giovanni Strona

The researchers found that, in their simulations, the ancient invading pathogens could often survive and evolve in the modern world, and about 3 per cent became dominant in their new environment.

About 1 per cent of those invaders presented unpredictable results - some caused up to one third of the host species to die out. The researchers said risks posed by this 1 per cent of released pathogens might seem small but given the sheer number of ancient microbes regularly released into modern communities, the researchers say these outbreaks represent a substantial danger.

“We found that invading pathogens could often survive, evolve and, in a few cases, become exceptionally persistent and dominant in the community, causing either substantial losses or changes in the number of living species,” Dr Strona said.

“Our findings therefore suggest that unpredictable threats so far confined to science fiction could in reality pose serious risk as powerful drivers of ecological damage.”

Prof. Bradshaw said the new findings show the risk of invasion of unknown “black swan” pathogens that can cause irreversible damage is not negligible.

“From that perspective, our results are worrisome, because they point to an actual risk deriving from the rare events where pathogens currently trapped in the permafrost and ice produce severe ecological impacts,” he said.

“In the worst, but still entirely plausible case, the invasion of a single ancient pathogen reduced the size of its host community by 30% when compared to our non-invasive controls. As a society, we need to understand the potential risk posed by these ancient microbes so we can prepare for any unintended consequences of their release into the modern world. The results tell us that the risk is no longer simply a fantasy that we shouldn’t be prepared to defend against.”