Climate change causing earlier signs of spring to become normal says Woodland Trust

Climate change could cause earlier signs of spring to become normal, conservationists have said.

The first leaves on trees and butterfly sightings are likely to happen earlier in the year as the climate gets warmer, according to the Woodland Trust's citizen science scheme, Nature’s Calendar.

The report, which gathers signs of each season from the public, found that reports of buds on trees and certain butterflies have come early this year, and that there is a general trend of earlier springs.

This year saw the warmest February on record for England and Wales.

One of the first trees to come into leaf is the elder tree and for the last five years, the Woodland Trust said. Members of the public have recorded it leafing earlier than the 20-year average by up to 16 days.

Other trees like the larch, rowan and oak have also been appearing two to three weeks early this year.

In addition, the Nature’s Calendar scheme recorded members of the public having seen brimstone butterflies, which are one of the first to be spotted each year, about two weeks before they are usually expected.

The Woodland Trust are warning earlier springs could have an impact on wildlife, with their foodchains becoming mismatched.

For example an oak leafing early could lead to an earlier peak in moth caterpillars which may affect the breeding success of blue tits that feed their young on them.

In addition, insects emerging too early before there are many flowers in bloom may not have sufficient food sources, according to some of those involved in the research.

The National Trust and the Royal Horticultural Society have also reported early flowering and blossoming at their sites.

Recent cooler weather, however, was said to have slowed the advance of spring in parts of the country, the National Trust ssaid.

The England “spring index” of key seasonal events which is based on the period 1998-2022 is now running around 8.9 days in advance of the average for the previous period which was between 1891-1947.

The index is based on the average dates of the first flowering of hawthorn, horse chestnut, the first appearance of an orange tip butterfly and swallows. It also draws on the Nature’s Calendar data.

Dr Judith Garforth is a citizen science officer at the Woodland Trust, and recorded an elder first leaf on February 20 in North Yorkshire. She noted spring is spreading north rapidly.

Dr Garforth said: “Whilst the sighting of an elder in leaf was a very welcome glimmer of spring after all the grim wet weather, it was much earlier than I’d expect, especially this far north.

“Overall though, the general trend is continuing with spring arriving earlier and becoming something like the new norm.

“Our data provides the clearest evidence of a changing climate affecting wildlife."

She continued: “Change has happened very quickly which is why the best option to help wildlife would be to slow it down– by reducing CO2 emissions and by planting more trees.

“We must continue to monitor this ever-important data we receive to keep tracking nature’s response.”

The Woodland Trust is asking for more volunteers to become citizen scientists and contribute sightings to Nature’s Calendar, to contribute to a biological record stretching back nearly 300 years and help scientists track changes.

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