Ancient virus genomes preserved in glaciers reveal the history of Earth's climate – and the way viruses adapt to climate change

As humans alter our planet's climate and ecosystems, scientists study Earth's history to predict the potential consequences of climate change. To do that, giant ice structures like glaciers function nature's freezers, archiving detailed records of past climates and ecosystems – including viruses.

We are a team of Microbiologists And Paleoclimatologists which studies ancient microorganisms, including viruses preserved in glacier ice. Together with our colleagues Lonnie Thompson, Virginia Rich and other researchers at Ice Core Palaeoclimatology Group At Ohio State University, we study interactions between viruses and their environment which are observed in ice cores from the Guliya Glacier on the Tibetan Plateau.

By linking the genomes of ancient virus communities to specific climate conditions preserved in glacier ice, our newly published research provides insights into how these Viruses have adapted to the Earth's changing climate within the last 41,000 years.

Read the story of viral genes

We primarily Metagenomes used – genome collections that capture the whole genetic content of all microorganisms present in environmental samples – to reconstruct viral genomes from nine different time intervals throughout the Guliya ice core. These time horizons span three major cold-warm cycles and supply a novel opportunity to look at how viral communities have modified in response to different climatic conditions.

Through our analyses we were capable of discover the genomes of Equivalent of 1,705 virus speciesThis has resulted in a greater than fifty-fold increase within the variety of known ancient viruses preserved in glaciers.

Only a few quarter of the virus species we found shared species-level similarities with all viruses identified in nearly 1,000 metagenomes previously collected in global datasets. Most of those overlapping species were also from the Tibetan Plateau. This suggests that not less than a few of the viruses preserved in Guliya Glacier originated from the region, but in addition speaks to the relative paucity of glacier viruses in available databases.

Using these recent reference genomes, we tried to “read” their stories.

One of a very powerful results was The viral communities differed considerably between cold and warm climate periods. The most distinct community of viral species on the glacier emerged about 11,500 years ago, coinciding with the most important transition from the last ice age to the Holocene. This suggests that the unique climate conditions during cold and warm periods strongly influenced the composition of viral communities. We suspect that these influences are likely on account of viruses being blown in from other locations by changing wind patterns and being subjected to selection pressure from the changing temperatures on the glacier.

Digging deeper, we next checked out how viruses interact with their hosts. We used computer models to match viral genomes with the genomes of other microbes that also exist in that environment. We found that viruses constantly infected Flavobacteriaa lineage of bacteria commonly present in glacial environments.

We also learned that viruses on the Guliya Glacier must “steal” genes from their hosts to control their metabolism. The following genes are encoded within the viral genomes: 50 auxiliary metabolism genes related to metabolism, including the synthesis and degradation of vitamins, amino acids and carbohydrates. Some of those genes were abundant in all nine time intervals studied, suggesting that they assist microbial hosts address the tough conditions on glacier surfaces and thereby enhance viral fitness.

Viruses not only infect and kill cells, but in addition likely alter the fitness of their hosts during infection, thereby influencing their ability to survive under the intense conditions of a glacial environment.

Climate change over time

Our findings provide a brand new perspective on how life in the shape of viruses has responded to climate change over tens of hundreds of years.

Understanding these ancient interactions provides a novel opportunity for future research in each virology and climate science. By studying the response of ancient viruses to past climate changes, researchers can gain worthwhile insights into how viruses adapt to ongoing global climate change.

We imagine that glacial ice, since it stores details about microorganisms and their ecosystems over time in each layer, will proceed to be a critical resource for studying Earth's climate history and the life that sustains it – especially given the rapid decline in glacial ice reserves.