Ancient diseases locked in ice could wipe out a third of humanity, study suggests

A new study has suggested the release of pathogens trapped in the world's permafrost and glaciers could pose a threat to humanity itself.

These "time-travelling" pathogens have been locked beneath the ice for millennia, but climate change could hasten their release.

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.

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But a new global study by Flinders University Professor Corey Bradshaw, and Dr Giovanni Strona of the European Commission Joint Research Centre, has calculated the ecological risks posed by the release of these unpredictable ancient microbes.

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

About one per cent of those invaders presented unpredictable results — some caused up to one-third of the host species to die out, while others increased diversity by up to 12 per cent, compared to the simulations where escape was not permitted in the simulations.

The risks posed by this one 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.

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"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," lead author 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."

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

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"In the worst, but still entirely plausible case, the invasion of a single ancient pathogen reduced the size of its host community by 30 per cent when compared to our non-invasive controls," Bradshaw said.

"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."

The study was published today in the open-access journal PLOS.

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