Spring to come to United States 3 weeks early

Rising global temperatures due to climate change will bring spring to the United States about three weeks earlier than usual in the decades to come, scientists said Wednesday.

While those who are weary of winter may welcome such news, scientists say the shift will also have long-reaching impacts on the growing season of plants and the animals that depend upon them.

"Our projections show that winter will be shorter -- which sounds great for those of us in Wisconsin," said Andrew Allstadt of the University of Wisconsin, Madison, a co-author of the study in the October 14 edition of the journal Environmental Research Letters.

"But long distance migratory birds, for example, time their migration based on day length in their winter range. They may arrive in their breeding ground to find that the plant resources that they require are already gone."

The research predicts the dates of leaf and flower emergence based on day length, and suggests spring will arrive a median of three weeks earlier over the next century.

The swiftest changes could be seen in plants in the Pacific Northwest and western US mountainous regions.

Smaller shifts should be seen in the south where spring already arrives early.

Researchers also predicted that there will be fewer so-called false springs, when an unexpected freeze occurs after spring plant growth has begun, over most of the US except for one area of the western Great Plains which is projected to see an increase.

"This is important as false springs can damage plant production cycles in natural and agricultural systems" said Allstadt.

"In some cases, an entire crop can be lost."

The study pointed out that the onset of spring plant growth has already shifted earlier over the past several decades, due to higher global temperatures.

The research team plans to expand its study to include all kinds of extreme weather, including droughts and heat waves, and how they affect bird populations in wildlife refuges.