Ice Age viruses provide clues about Earth’s past and future climate

Viruses preserved in glacier ice contain valuable clues about past climate and environmental changes on Earth.

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.

Trapped in the cold heart of glaciers, ancient viruses offer insight into Earth's stories, waiting to be interpreted.

Viruses as time capsules

At an elevation of over 20,000 feet, the Guliya Glacier in the far northwest of the Tibetan Plateau holds a vast archive of our planet's climate history. From here, scientists have extracted ice cores that serve as time capsules recording past climate conditions.

By analyzing these ice cores, microbiologists reconstructed pieces of virus DNA and identified nearly 1,700 species of viruses, about three-quarters of which were previously unknown to science.

These prehistoric viruses do not pose a health threat to humans, but they provide information about the ability of organisms to survive under extreme conditions.

“Before this work, the link between viruses and large-scale changes in Earth's climate was largely unexplored,” said ZhiPing Zhong, lead author of the study and a research associate at the Byrd Polar and Climate Research Center at Ohio State University.

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

Viral behavior during climate change

Due to the increasing impacts of global warming, it has become even more urgent to collect these ice cores before they disappear, further increasing their scientific value.

For example, the ice samples examined in the study provided clear snapshots of virus behavior during three major cold-to-warm transitions over the past 41,000 years.

“Glacier ice is so valuable and we often don’t have the large amounts of material needed for virus and microbial research,” Zhong noted.

Among the various newly reported virus types, the most unique viral community is about 11,500 years old, dating to the transition from the cold last ice age to the warm Holocene.

This suggests that global temperature fluctuations have triggered microbial responses. Zhong cautions that it is too early to say for sure, although the results at least point to a possible link between viruses and climate change.

The dance of viruses and climate

Using cutting-edge sequencing technologies, the team examined the viruses' genetic signatures in more detail and found that while most of the viruses were specific to the Guliya Glacier, about a quarter shared features with organisms from other parts of the world.

“This means that some of them may have been imported from areas like the Middle East or even the Arctic,” Zhong said.

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

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

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

Predicting future virus behavior

Insight into the DNA of ancient viruses could open a Pandora's box of fascinating puzzles and groundbreaking revelations.

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

“I'm optimistic about what can be achieved here because if we work together, these techniques can help us address a wide range of scientific problems,” Thompson said.

Unfortunately, the clock is ticking. As global warming threatens to destroy these invaluable archives, it is crucial to delve deeper into Earth's climate history.

“The opportunity to study ancient viruses and microbes in ice with this team is a testament to the support we've had in exploring new interfaces,” Sullivan said, emphasizing the collaborative effort behind this research.

Every ice core recovered 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 Joint Genome Institute of the U.S. Department of Energy.

The study was published in the journal Natural Geosciences.

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