Spring is arriving up to a week earlier than it did 40 years ago in response to a warming trend in the U.S. Northeast, Cornell University researchers are reporting. They base their conclusion on a study of historical bloom-date records for lilacs, apples and grapes, which suggests that nature's calendar is changing due to an increase in greenhouse gases.

In one of the first documented cases that plants in the Northeast are responding to climate change, the Cornell scientists and their colleagues at the University of Wisconsin say that lilacs are blooming about four days earlier, and apples and grapes six to eight days earlier, than in 1965. The findings in the study -- the first to encompass the U.S. Northeast -- are consistent with similar reports in other regions of the United States and in Europe.

"We find consistent evidence that the general warming trend of the past several decades is resulting in a significant advance of spring blooming," says David W. Wolfe, lead author of the new report and professor of plant ecology in the Department of Horticulture at Cornell.

The researchers used several data sets and analyses to examine the blooming trends from 1965 to 2001 for lilacs, apples and grapes, which are all woody perennials, in the Northeast. The study appears online and will be published in a forthcoming issue of the International Journal of Biometeorology.

Wolfe notes that the Northeast's average annual temperature has increased by 1.8 degrees Fahrenheit since 1900, with winters (December to February) showing the greatest rate of warming, with an average increase of almost 3 degrees Fahrenheit over the past 100 years and of 4.4 degrees Fahrenheit over the past 30 years.

Since most scientists anticipate that the warming trend and increase in greenhouse gases, such as carbon dioxide, will continue, Wolfe says, there is a need to more broadly monitor the consequences for crops, animals and natural areas.

He points out that the recent warming trend has many implications. For example, it could favor some invasive species and alter important interactions between plants and pollinators, insect pests, diseases and weeds. If the interdependence and synchrony between animals and plants are disrupted, he says, the very survival of some species could be threatened. Climate change could also affect plant and bird migration patterns, animals' hibernation patterns, reproductive cycles, woodland composition, plant pathogens and the availability of plant food for insects and animals.

The warming trend also is extending the growing season in the Northeast by several days, Wolfe says. While this may benefit the growth of some crops, such as watermelon, tomatoes, peppers, peaches and some red wine grape varieties, hotter summers could negatively affect sugar maple, apples, Concord grapes and cool-season-adapted vegetable crops, such as potatoes and cabbage.

"Although this is not the first paper to document plants responding to climate change, few others are relevant to the Northeast, and the lilac data set is particularly unique and powerful," Wolfe says.

The researchers analyzed data from 72 locations throughout the region where genetically identical lilacs were planted during the 1960s and 1970s to help farmers determine whether to expect an early or late spring and to help them predict spring pest pressure, planting and harvest dates and yields. But now, the historical records from these sites are being used for a completely different purpose: to document the effects of climate change.

The researchers also used a previously validated spring index computer model that predicts lilac bloom dates from local weather data, and they examined New York state bloom-date records of Concord grapes in Fredonia and apple data in Geneva, Poughkeepsie and Peru.

Co-authors of the paper are climate scientist Mark Schwartz of the University of Wisconsin-Milwaukee; Alan Lakso, Robert Poole and Nelson Shaulis, professors of horticulture at Cornell's New York State Agricultural Experiment Station in Geneva; and Yuka Otsuki, a Cornell doctoral student working with Wolfe. The study was funded in part by the U.S. Department of Agriculture.

Related World Wide Web sites: The following sites provide additional information on this news release. Some might not be part of the Cornell University community, and Cornell has no control over their content or availability.

The article online in International Journal of Biometeorology for subscribers only:
< http://www.springerlink.com/index/10.1007/s00484-004-0248-9>
"Climate Change and Northeast Agriculture: Developing an Education Outreach Agenda,"

Proceedings from a 2004 symposium:
<http://www.hort.cornell.edu/department/faculty/wolfe/Proceedings11-17-04.pdf>