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atherine Yansa, a Biogeographer and Assistant Professor of Geography at Michigan State University, studies plant fossils (pollen, charcoal, seeds, and leaves) preserved in lake sediments. She uses this information to understand how vegetation and climate have changed in North America over the last 17,000 years.

Global warming may outpace the trees

Trees are stuck in one place. They can't migrate north if the climate gets too hot for them. But they can expand their ranges, with seedlings colonizing new, cooler territory.

Catherine's research shows that, as temperatures warmed at the end of the last Ice Age, white spruce crept northward at about 13 miles per decade. However, today's warming trend is going about four times faster than in prehistoric times. If the climate changes too suddenly, the trees won't be able to keep up—and could go extinct in some areas.