Thursday, 5 April 2012

Bluebells chime with climate change and spring creep




My furtive picture of some of the first bluebell flowers at Kew Gardens in 2012. I took it on Tuesday, on the way back from a very brief interview with Alex Deakin from BBC One Breakfast weather about our early and rather robust spring. This year the bluebells flowered in March for first time since records began. The opening of the bell-like blooms on the 29th of March marked a new milestone for the insidious spring creep.

It wasn’t so long ago that Kew held a Woodland Wonders festival in May to celebrate the bluebells blooming. Now celebrating spring is a little like working out when Easter will be held, without the quirky lunar formula.

This year’s first flowering of the bluebells is six days earlier than the previous record, held by the years 2002 and 2007. Back in the 1980s and 90s, the average date for the first flowering in each decade was 25th of April and 21st of April. The march (excuse the pun) had begun.

The decadal average for the new millennium is 13th April and slipping ever closer to the start of the month. It’s now 20 years or so since the bluebells started flowering in May and no matter how bleak our winter or spring we don’t expect to be holding a bluebell festival in that month ever again.

The string of warm sunny days since mid-March have brought forward lots of flowering shrubs as well – things like Prunus ‘Kanzan’, Buxus sempervirens and Malus floribunda. The magnolias have come and almost gone at Kew Gardens. The boastfully named Glory of the Snow (Chinodoxa) has been carpeting one of our lawns blue for weeks and the fritillarias are about to hit their peak.

Clearly lots happening all at once and we expect a concertinaed as well as early spring. None of which proves climate change is occurring or caused by humans. That has been demonstrated beyond doubt by climate change scientists.

Climate change has also been well corroborated with seasonal observations over hundreds of years. Grape vines in Burgundy now ripen up to 4 weeks earlier than when Charles V downed a goblet in the 14th century.

Spring creep, as it is called, has already caused mismatches between things that rely on day length and those that respond to temperature. Caterpillars in the Netherlands are peaking 16 days earlier than in 1985, leading to 90% decline in population of the migratory pied flycatcher that now arrives a few weeks too late to feast. The hungry caterpillars presumably munch their way through more plants as a result.

And various flowers and pollinator are now getting out of sync. Our gardens, flowers, insects and animals are all telling us something. The bluebells are ringing in change, whether we like it or not.


Notes: In case you are wondering, 99% of our bluebells are the native English Bluebell - Hyacinthoides non-scripta (we weed out Spanish Bluebells (Hyacinthoides hispanica) and their hybrids with the local species).

No comments: