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The changes in bloom times are glaring in Inouye's Rocky Mountain plots. "Just 10 years ago, this project was perfectly timed with the academic calendar," he explains. In mid-May, as soon as Inouye wound up his teaching duties at the University of Maryland, he would head out to his beloved mountains just in time to track wildflower blooms. But now some of the flowers he studies begin blooming by mid-April. To continue his research, Inouye has had to pay assistants to track flowering that occurs before he is able to arrive on site.

The careful tracking of bloom times over many years provides an important indicator of climate change. But Inouye's research also shows that bloom times are part of an intricate and often delicate natural dance that is in many cases disrupted by climate change. Inouye is an expert on pollinators like bees and butterflies, and his research has shed light on a growing problem known as "phenological mismatches," in which plants and pollinators adapt at different rates to a changing climate.

In the case of the Aspen sunflower (Helianthella quinquenervis), for instance, global warming has led to smaller snow packs in the mountains, which means earlier snow melts -- an important cue for wildflower blooms. Paradoxically, as the Aspen sunflowers are triggered to bloom earlier each year, it becomes more likely that they will be damaged by exposure to late spring frost. Inouye's research shows that from 1992 to 1998, such frosts on average killed about a third of the Aspen sunflower buds in his plots. Between 1999 and 2006, however, the typical percentage doubled, with nearly three-quarters of all buds being killed by frost in an average year. Inouye says he has seen whole fields of this particular flower (shown in the photograph) decimated by frost. "Given the rate of global warming, we'll see some wildflower extinctions," he says. "There is little doubt about that."