In a modest office jutting off the brutalist brick building of Hutchison Hall at the University of Rochester, geologist Vasilii Petrenko sits behind a desk looking out at the Genesee River.
“It’s really different than the ice you’d see in the river, in the sense that it’s full of air bubbles,” he says, referring to glacial ice in Greenland and Antarctica.
Year after year (800,000 years if we’re talking Antarctica), snow compacts under its own weight forming strata that encapsulate the space—the air—between flake structures. “And these [ice cores] are perfect samples of past atmospheres.”
Petrenko, an assistant professor in the U of R’s department of Earth and Environmental Sciences, studies the dynamics of Earth’s natural climate system and how it works from the perspective of climate pasts. As a scientist, he says, the object of study is ideally examined in a well-controlled lab where one variable can be tweaked at a time. But with the Earth, he says, “We can’t do that.” The drilling and examination of glacial ice core samples from Greenland and now Taylor Glacier, Antarctica, allow scientists like Petrenko to hypothesize the continuity of spikes in global temperatures as anthropogenic (human-caused) and natural ecological shifts occur.
Per molecule, the greenhouse gas methane (CH4) is about 25 times more potent than carbon dioxide (CO2). Considering contributions from different anthropogenic emittants today, methane is the second-largest contributor to the warming of the planet after CO2.
“It has also been a factor in the past,” Petrenko says. “When temperatures are high, methane concentrations are high. When temperatures are low, methane concentrations are low. It reinforces the warming, and what we see is that there are these really rapid warming events, particularly in the northern hemisphere, that happen periodically, and a couple of these happened during the last deglaciation when the Earth was transitioning from the last glacial maximum, when Rochester was buried under a mile or more of ice.”
Measuring and mapping up to 800,000 years of past atmospheres on Earth provide researchers with a schematic view of what a balanced climate system looks like, how it acts, and how the planet reacts out of balance.
“The ultimate goal is to better understand the Earth’s climate system, and get a more predictive power for the future,” Petrenko says.