Glaciers and ice packs provide a record of human influence on the world, which scientists study to better understand our history. A team at Ohio State University are anticipating the same thing happening in the future, when ice archaeologists will one day identify the spread of Covid-19 through the sharp drop in pollution in a thin layer of ice.
The reduction in industrial activity occurring around the world is temporarily cleaning up the air, as demonstrated by the citizens of normally heavily polluted cities being able to see distant mountains for the first time. Although some reports of nature returning to cities are fake, others are real and these almost certainly represent only the most visible examples of biological changes induced by so much of humanity staying home.
As each year's snow settles on a mountain top or ice sheet, its composition is set by the air from which it comes, creating a record of the atmosphere at the time. “These records will be locked into the ice and preserved,” Professor Lonnie Thompson said in a statement. “And that means that 100 or 200 years from now, that ice will be showing anything that is in the atmosphere now, and that will tell future generations about what is happening now.”
Of course, if future generations can read our communications, they may not need to drill the ice to understand this year's events. On the other hand, if digital records prove far less enduring than medieval manuscripts, the absence of nitrate and sulfate levels in future ice cores may indicate an otherwise forgotten global event that occurred in early 2020. Thompson added that future glaciologists may also develop more advanced techniques enabling them to find Covid-19 pandemic signatures currently beyond his capacity.
“It’s like being a detective as we are with the ice cores – if all you have are the ice core records, and you don’t have the human history, you might miss the connection," said Professor and co-author Ellen Mosley-Thompson.
Previously, the pair have observed a drop in lead in Greenland ice cores coinciding with the Black Death's destruction of European industry, as others have done for even earlier plagues. The two have also been studying the viral record more directly. In 2018, they published a paper in Frontiers in Microbiology on how to find and analyze bacteria in ice cores. They are now working on something similar for viruses, although prospects for SARS-CoV-2 getting deposited in the ice of Greenland or Antarctica and found centuries later look slim.
Thompson issued one caveat to his picture of future scientists learning about Covid-19 through ice cores, saying: “Of course, this assumes that glaciers will continue to exist in the future.” If they don't, it will signal a disaster that will make the pandemic look tiny by comparison and one that likely will have been our fault.