Nature has a great way of giving clues to the clueless. When spring arrives a little earlier, and fall stays a bit later, it’s not necessarily a good thing.

Phenology is the study of how climate impacts the blooming of plants in the spring, their dying back in the fall, and the migratory and feeding habits of animals. To be sure, no single year of early daffodils or cherry blossoms is a demonstrable sign of climate change. We’ll continue to have warmer winters, and colder winters. But the overall trend suggests that climate change includes seasonal changes. Earlier springs, later falls, with some confused animals as a possible result.

One of the first big phenology fans was Henry David Thoreau. He obsessed, in a scientist’s kind of way, over the first signs of spring and fall each year, documenting every bud, bulb, migrating bird, and turning leaf. The National Wildlife Federation’s magazine did a piece a few years back on how Thoreau’s obsession gained new scientific value as modern-day scientists compared how much earlier spring now springs around Walden Pond. Highbush blueberries, for example, now bloom two weeks earlier than they did in Thoreau’s time. Thoreau did his phenology for kicks and giggles. Now, a lot of scientists make a living at it.

The University of Vermont is showing data that suggests that the state’s prized sugar maples may be slowly migrating north. Sugar production in Vermont has trended downward in recent decades, while production has increased sharply to the north in Canada. The university’s Proctor Maple Research Center also has a study underway to see how rising temperatures might affect the fall colors -- a source of big tourist bucks for many parts of the country in the autumn.

Scientists from Southern Oregon University and Germany’s Geisenheim Institute have accessed more than two centuries’ worth of vineyard records from the Rhine Valley. For a century from the late 1700s, the time of year for grape harvests for Riesling wine remained pretty constant -- actually happening on average about four days later by 1895. But from 1895 till today, the grapes were ripe a full 25 days earlier. The scientists say that may turn out to be good news for Rhine wines, but early blooms in other wine regions around the world might make every year a very bad year.

Agencies like the U.S. Geological Survey and the National Park Service study phonologic changes on the ground, and also by remote camera.

Phenology is a big deal. Please do not confuse it with phrenology. Phrenology, with an “r” in the middle, is the study of someone’s character by reading the bumps and contours of the top of their head. I wouldn’t put too much stock into that one. Phenology, without the “r”, is a key indicator of our biological prospects in the future. It tells us when songbirds or pollinators arrive. If your pollinators are late and your crops bloom early, expect a lousy crop. It tells us, through the work of researchers like Camille Parmesan of the University of Texas, when butterflies have evacuated warmer climates and moved to higher latitudes, or higher altitudes. It tells us when tree species like the sugar maples of Vermont have begun a northerly retreat -- and what it may mean for people who make their living from them.

The government-sponsored University Corporation for Atmospheric Research is turning phrenology into a participatory event. Project BudBurst offers a chance for students and others to collect and report their sightings of the first signs of spring and fall. My own anecdotal contribution involves not plant buds, but wildlife. In recent years, I’ve spotted five armadillos in the Atlanta suburbs, in an area where they’re not supposed to be living. Technically, the ones I’ve spotted weren’t living, they were road kill. The adorable little armored possums have been marching north for a century and a half, but their range seems to have greatly expanded in recent years. A warming climate is a likely, but not proven, suspect.


Peter Dykstra is the former executive producer of CNN's Science, Tech and Weather Unit.

Green States: A planet for all seasons
Nature has a great way of giving clues to the clueless. When spring arrives a little earlier, and fall stays a bit later, it’s not necessarily a good thing.