Ice age viruses hold clues to Earth's past and future climate

Viruses preserved in glacial ice hold valuable clues about Earth’s ancient climate and environmental changes.

As the world faces the consequences of climate change, looking back at these ancient viral footprints can help us understand the complex interactions between life and the environment over millennia.

Locked away in the cold heart of glaciers, ancient viruses offer a glimpse into the stories of Earth’s past, waiting to be interpreted.

Viruses as time capsules

At an altitude above 20,000 feet, the Guliya Glacier in the far northwestern Tibetan Plateau harbors an immense repository of our planet’s climatic history. From here, scientists have extracted ice cores, which serve as time capsules recording past climate conditions.

By analyzing these ice cores, microbiologists reconstructed pieces of virus DNA and identified nearly 1,700 viral species, with about three-fourths of them previously unknown to science.

These prehistoric viruses, rather than posing a health threat to humans, provide insight into the survival capacity of organisms in extreme conditions.

“Before this work, how viruses linked to large-scale changes in Earth’s climate had remained largely uninvestigated,” said ZhiPing Zhong, lead author of the study and a research associate at the Byrd Polar and Climate Research Center at The Ohio State University.

The viruses adapted to survive, influencing their hosts’ survival strategies and shedding light on the interplay of life and climate throughout history.

Viral behavior during climate transitions

The intensifying effects of global warming have amplified the urgency to collect these ice cores before they vanish, adding to their scientific value.

For instance, the ice samples examined in the study offered clean snapshots of viral behavior during three major cold-to-warm transitions in the last 41,000 years.

“Glacial ice is so precious, and we often don’t have the large amounts of material required for virus and microbe research,” Zhong noted.

Among the various types of new viruses reported, the most unique viral community dates back around 11,500 years ago, during the transition from the cold Last Glacial Stage to the warm Holocene.

This suggests that global temperature shifts triggered microbial responses. Zhong cautions that it is still too early to say for certain, although the findings at least indicate the potential connection between viruses and climate change.

The dance of viruses and climate

Using advanced sequencing technologies to get a closer look at their genetic signatures, the team found that while most of the viruses were specific to the Guliya Glacier, about one-fourth shared traits with organisms from other parts of the world.

“That means some of them were potentially transported from areas like the Middle East or even the Arctic,” said Zhong.

Understanding viral evolution during climatic extremes provides vital clues for predicting how modern viruses might react to future ecosystem warming.

“To me, this science is a new tool that can answer basic climate questions that we couldn’t have answered otherwise,” said Lonnie Thompson, co-author of the study and a professor of earth sciences at Ohio State.

The study’s interdisciplinary approach, supported by institutions like Ohio State’s Byrd Polar and Climate Research Center and the Center of Microbiome Science, was crucial to its success, noted co-author Matthew Sullivan, a professor of microbiology at Ohio State.

Predicting future virus behavior

The glimpse into ancient viral DNA could open up a pandora’s box of intriguing puzzles and breakthrough revelations.

The techniques used on Earth could also equip scientists with the tools necessary to search for life in outer space, such as microbes frozen in Martian ice fields or beneath the icy shells on distant celestial bodies.

“I’m optimistic about what can be done here, because if we work together, these techniques have much potential to help us start tackling a large array of scientific issues,” said Thompson.

Unfortunately, the clock is ticking. With global warming threatening to melt these invaluable archives, it’s crucial to dig deeper into Earth’s climatic history.

“Getting to study ancient viruses and microbes in ice with this team is a witness to the support we had to explore new interfaces,” said Sullivan, underscoring the collaborative effort behind the research.

Every ice core retrieved and every virus discovered brings us one step closer to understanding our planet’s past and predicting its future.

The study was supported by the National Science Foundation, the Chinese Academy of Sciences, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, and the U.S. Department of Energy’s Joint Genome Institute.

The study is published in the journal Nature Geoscience.

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