Climate change to bring spring three weeks earlier to US

Driven by rising global temperatures, winter will be shorter and the onset of spring plant growth will shift by a median of three weeks earlier over the next century, scientists have projected.

The findings have long term implications for the growing season of plants and the relationship between plants and the animals that depend upon them.

"Our projections show that winter will be shorter - which sound great for those of us in Wisconsin," explained one of the study authors Andrew Allstadt from University of Wisconsin-Madison, US.

"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," Allstadt noted.

The researchers applied the extended Spring Indices - statistical models that scientists have developed to predict the "start of spring" at a particular location -- to predict the dates of leaf and flower emergence based on day length.

These general models capture the phenology -- key seasonal changes from year to year - of many plant species.

Their results showed particularly rapid shifts in plant phenology in the Pacific Northwest and mountainous regions of the western US, with smaller shifts in southern areas, where spring already arrives early.

The researchers also investigated so-called 'false springs' - when freezing temperatures return after spring plant growth has begun.

They showed that these events will decrease in most locations. However a large area of the western Great Plains is projected to see an increase in false springs.

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

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

The study was published in the journal Environmental Research Letters.