As climate change continues to intensify, experts warn that mass extinctions may be on the horizon. Models parameterized by current distributions often project dire outcomes for Earth’s biodiversity, with some studies predicting up to 37% species declines in the regions under study. Yet the fossil record doesn’t necessarily corroborate these grim forecasts. While fossil evidence shows that climate shifts have historically altered local species compositions, there is little evidence of widespread extinctions after the major climate shake-ups of recent ice ages.

The work of Steve Jackson, the USGS Director of the Southwest and South Central CASCs, is at the center of this so-called Quaternary conundrum, the difference between how species have responded to a changing climate in the past vs how scientists project species will respond in the future. As highlighted by a recent feature in the online publication Undark, Jackson discovered fossil evidence of an extinct spruce species in the hills of the Louisiana/Mississippi border, far to the south of where cold-loving modern spruce trees live. The Critchfield Spruce is the only known tree species to have gone extinct at the end of the Pleistocene ice age, a period characterized by dramatic climate seesaws. This raises the question: did most plants adapt or migrate fast enough to survive those rapid changes? Or were there other species that, like Critchfield’s Spruce, succumbed to climate change? Today, researchers are applying novel gene extraction and DNA sequencing methods to fossils to learn more about the tree’s extinction. They hope these results will provide insights into how modern species may respond to 21^st century climate change.

“It may or may not be representative,” Jackson says. “Each extinction is different. But even knowing the details of a single extinction can be instructive in telling us, ‘These are the sorts of things that can happen.’”