Study predicts plants will start budding three weeks sooner by end of century as climate change exerts direct effect on seasonal calendar

This article is more than 4 years old

This article is more than 4 years old

Scientists have confirmed what gardeners have long suspected: spring is coming much earlier in the US, with plants projected to bud three weeks earlier by the end of the century because of climate change.



By 2100 plants will green up 22.3 days earlier in much of the country, with the biggest jump on spring occurring in the western US.

In the Pacific north-west the researchers expected an even shorter winter with spring kicking in up to 28.5 days earlier by the end of the century.

The findings, published on Wednesday in Environmental Research Letters, suggest even bigger shifts in the plant calendar due to climate change than had been expected.

Earlier this year another team of researchers suggested that spring was arriving as much as 14 days earlier in most parts of North America because of climate change.



The researchers from the Hawthorne Valley Farmscape Ecology Programme drew on thousands of records, from frog mating calls to bird migration patterns and tree and plant flowerings, to compare the shift in timing of natural events.

In some parts of the country, including Wisconsin, some flower species, such as wild geranium, were blooming 24 days earlier in 2012 than in 1945.

The newest group of researchers, from government scientific agencies as well as universities, combined historical records of lilac and honeysuckle growth with 19 climate models to project first leaf and first bud in the coming decades.

“We know spring is getting earlier. But we provide actual evidence for how much earlier,” said Andrew Allstadt, an ecologist at the University of Wisconsin-Madison, who was part of the research team.

The change would have far-reaching effects - both for farming and other industries and the natural world.

“The timing of events is important,” Allstadt said. “If plants are shifting earlier in the year, there is a worry that the animals that depend on the plants won’t keep up with those shifts.”



Those living in warmer parts of the US, such as the south, are unlikely to see as big a difference in the arrival of spring, because it is already so warm.

But much of the country will see a shorter winter, Allstadt said.

The biggest factor triggering the first green shoots of spring was the slow build-up of milder weather over the course of the year – rather than a burst of above-average days in February or March, he said.

That was especially the case at higher altitudes and across the wind-swept Great Plains, he said.

The researchers did not find a rise in false springs, or hard frosts that could damage or kill off a new season’s growth.