Climate change is driving plants to flower earlier and earlier, a study has found. By studying records going back as far as 1753, a research team has shown that the average first flowering date of UK plants is a month earlier than it was before 1986, and it shows a strong correlation with our warming climate.


The team of researchers, led by the University of Cambridge, analysed more than 400,000 records from the citizen science database Nature’s Calendar. Since the 18th Century, gardeners, scientists and naturalists in the UK have been contributing observations of the changing seasons. In 2000, the Woodland Trust and the Centre for Ecology & Hydrology collated these into Nature’s Calendar, which now comprises around 3.5 million records.

These 400,000 records were of the first flowering dates of 406 different species of trees, shrubs, herbs and climbers around the UK. The team calculated the average first flowering dates in the periods 1752-1986 and 1986-2019, and compared these with monthly climate records. They found that the average first flowering dates were almost a full month earlier than they were in the 1752-1986 period.

The team warn that if warming continues at the same rate, eventually, spring could start in February in the UK.

“We can use a wide range of environmental datasets to see how climate change is affecting different species, but most records we have only consider one or a handful of species in a relatively small area,” said Professor Ulf Büntgen from Cambridge’s Department of Geography, the study’s lead author. “To really understand what climate change is doing to our world, we need much larger datasets that look at whole ecosystems over a long period of time.”

Some crops are at risk if they flower too early. For example, if fruit trees flower early, a late frost could kill off the whole crop. A bigger environmental risk of early flowering is called ‘ecological mismatch’. “Plants, insects, birds and other wildlife have co-evolved to a point that they’re synchronised in their development stages,” explained Büntgen. “A certain plant flowers, it attracts a particular type of insect, which attracts a particular type of bird, and so on.

“But if one component responds faster than the others, there’s a risk that they’ll be out of synch, which can lead species to collapse if they can’t adapt quickly enough.”

Nature’s Calendar is open to anyone who wants to get involved with tracking our changing climate. “Anyone in the UK can submit a record to Nature’s Calendar, by logging their observations of plants and wildlife,” said Büntgen. “It’s an incredibly rich and varied data source, and alongside temperature records, we can use it to quantify how climate change is affecting the functioning of various ecosystem components across the UK.”

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Sara RigbyOnline staff writer, BBC Science Focus

Sara is the online staff writer at BBC Science Focus. She has an MPhys in mathematical physics and loves all things space, dinosaurs and dogs.