新澳门六合彩内幕信息

Spring Is Springing Earlier in Polar Regions Than Across the Rest of Earth

Earth Is Experiencing Earlier Springs, but Nowhere So Much and So Fast as at High Latitudes

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Spring in Greenland
Spring is springing earlier at northern latitudes, such as in Greenland, than it is at lower latitudes. (Eric Post/新澳门六合彩内幕信息 Davis)

Spring is arriving earlier, but how much earlier? The answer depends on where on Earth you find yourself, according to a study led by the University of California, Davis.

The study, published in Nature鈥檚 online journal Scientific Reports, found that for every 10 degrees north from the equator you move, spring arrives about four days earlier than it did a decade ago. This northward increase in the rate of springtime advance is roughly three times greater than what previous studies have indicated.

For example, at southern to mid latitudes such as Los Angeles, New Orleans or Dallas, the study suggests spring might be arriving a mere one day earlier than it did a decade ago. Farther north, in Seattle, Chicago or Washington D.C., it might be arriving four days earlier. And if you live in the Arctic, it might be arriving as much as 16 days earlier.

鈥淭his study verifies observations that have been circulating in the scientific community and popular reports for years,鈥 said lead author Eric Post, a fellow of the John Muir Institute and polar ecologist in the 新澳门六合彩内幕信息 Davis Department of Wildlife, Fish and Conservation Biology. 鈥淵es, spring is arriving earlier, and the Arctic is experiencing greater advances of spring than lower latitudes. What our study adds is that we connect such differences to at higher latitudes.鈥

Accelerated spring                                             

The study is the most comprehensive analysis to date of springtime advance, or phenology, as you move north with latitude. Such signs include birds migrating, flowers blooming, amphibians calling and the emergence of leaves.

Cottongrass, Greenland
Cottongrass blows in the Greenland wind. (Eri Post/新澳门六合彩内幕信息 Davis)

The researchers analyzed 743 previously published estimates of the rate of springtime advance from studies spanning 86 years across the Northern Hemisphere, as well as rates of springtime warming over the same range of years and latitude. Even after accounting for differences in the length, time and location of those previous studies, the relationship between earlier springs and higher latitudes was strong.

Unknowns for birds, migratory species

Springtime provides important biological cues for many plant and animal species, and it is unclear how an accelerated spring could play out for these species across the planet.

eggs in nest
A nest holding the eggs of northern wheatears rests on branches in Greenland. These birds are long-distance migrants, overwintering in sub-Saharan Africa and breeding in the Arctic. With earlier springs happening faster at higher but not lower latitudes, the birds may find themselves "late for dinner" if the insects they flew north to feast upon have already emerged. (Eric Post/新澳门六合彩内幕信息 Davis) 

The study notes that impacts to migratory birds are a potential concern. Many birds move from tropical zones to higher latitudes, such as the Arctic, to breed.

鈥淲hatever cues they鈥檙e relying on to move northward for spring might not be reliable predictors of food availability once they get there if the onset of spring at these higher latitudes is amplified by future warming,鈥 Post said. 鈥淭he springtime emergence of the plants and insects they鈥檒l eat when they arrive is happening faster than the changes at the lower latitudes those birds are departing from.鈥 

The study鈥檚 co-authors are Byron Steinman from the University of Minnesota Duluth, and Michael Mann from Pennsylvania State University.

The research received financial support from the National Science Foundation.

Media Resources

Kat Kerlin, 新澳门六合彩内幕信息 Davis News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu

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