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Plants in UK Bloom a Month Earlier Than in 1980s: Study

Scientists warn that climate change–induced early flowering could have negative effects on wildlife, agriculture, and gardening.

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Natalia Mesa

Natalia Mesa is an intern at The Scientist. She has a PhD in neuroscience from the University of Washington and a bachelor’s in biological sciences from Cornell University.

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Feb 2, 2022

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In the United Kingdom, spring flowers are blooming a month earlier than a few decades ago due to the warming climate, a new study reports. 

Climate change, which is largely caused by fossil-fuel emissions, brings late fall and early spring to many parts of the world. The new study, published today (February 2) in the Proceedings of the Royal Society Bwarns that if the trend holds, it could lead to profound negative impacts on wildlife and agriculture—and potential species collapse.

“The results are truly alarming, because of the ecological risks associated with earlier flowering times,” Ulf Büntgen, a geographer at the University of Cambridge, tells The Guardian. “When plants flower too early, a late frost can kill them—a phenomenon that most gardeners will have experienced at some point.”

Flowering plants go dormant in the winter to protect themselves from the winter chill, Büntgen tells CNNBut an early spring can rouse plants early, making them more susceptible to harm from frosts. This could spell major economic problems for farmers if fruit trees flower early and late frosts damage or kill crops, reports the Guardian. 

The researchers examined 420,000 historical records documenting the date of first flowering for 406 native species of trees, shrubs, herbs, and climbers, going back to 1793. This data is recorded in a citizen science database known as Nature’s Calendar, which is maintained by the Woodland Trust and the Centre for Ecology and Hydrology. The study examined the first flowering dates of blooms throughout the UK, from the Channel Islands to Shetland, and from Northern Ireland to Suffolk. 

The researchers divided the full dataset into two parts: records until 1986, and from 1987 onward, and found the average first flowering date from 1987 to 2019 was almost a month earlier than the average first flowering date from 1753 to 1986. Herbs, which experienced the largest shift on average, flowered 32 days earlier. Trees bloomed an average of 14 days earlier, and shrubs flowered an average of 10 days earlier.

The scientists found that the earlier flowering dates correlated strongly with the average daily maximum temperature from January to April in the UK, which rose from 7.8 °C from 1952–1986 to 8.9 °C  from 1987–2019. 

Not all species are adapting at the same rate to warmer temperatures. In addition to the risk of damage from frosts, the study warns that species, which may be reliant on each other for food or survival, could get out of sync with one another, a concept known as ecological mismatch. Ecological mismatch could have disastrous consequences for wildlife and for food production. This phenomenon is already observable, reports the Guardian—for example, between orchids and bees. Warmer spring temperatures affect bees much more than orchids, and the pollinators tend to venture out before the flowers have bloomed. 

“That can lead species to collapse if they can’t adapt quickly enough,” Büntgen says.