British seasons start to shift

In the future, snowdrops will be out in January, primroses in February, mayflowers and lilac in April and wild roses in May, the ponds will be full of tadpoles in March and a month later even the oaks will be in full leaf.

If that isn't enough, autumn probably won't begin until October.

The seasons are becoming muddled, according to the Woodland Trust, which has analysed the biggest survey yet of when spring and autumn start.

It says many seasonal events in nature are being thrown out of sequence in a way that will become increasingly common as climate change takes hold. For its Phenology Project, 17,000 people noted the dates on which natural events took place in autumn last year and spring this year.

The results show that higher temperatures pushed "almost every characteristic of this year's spring" forward by between a week and three weeks compared with last year.

And autumn last year was delayed by up to 12 days compared with 2000 - which itself had the longest growing season on record (330 days) according to scientists at the University of East Anglia's Tyndall Centre for Climate Change.

"On average this spring, insects such as bumble bees and butterflies were three weeks early, while plants flowered two weeks ahead and many birds arrived more than a week earlier than usual," the Trust found.

It believes this is not just a one-off but part of a significant trend.

The Nineties were the warmest decade on record, with temperatures far higher than the 30-year average.

"Last year was a typical year, while this year was around three degrees warmer," said Tim Sparks, environmental scientist at the Centre for Ecology and Hydrology at Monkswood.

"The work on climate change shows years like 2002 will become typical and years like 2001 will become extinct."

If that is true, snowdrops will be out in January instead of February and most butterflies will appear in April instead of May. This year, the holly blue butterfly was 22 days early, appearing on 19 April. The small white was 20 days early, the red admiral 19 and the comma 21.

The hawthorn - known as May after the month in which it usually flowers - was out in April, as were horse chestnut flowers, also traditionally linked with May. Wild roses, which authors from Chaucer on have known as a flower of high summer, were in full bloom in May instead of June.

The Woodland Trust believes the trend may have serious consequences, saying: "The arrival of spring is no longer constrained to its traditional March slot and the end of autumn now continues well beyond late October. Interconnected and often complex relationships between trees, insects and animals in woods are affected by early spring arrivals."

With warmer temperatures this year, insects emerged up to several weeks early to take advantage of the food supply - but the birds that time their migrations to take advantage of the insects arrived only a few days early.

"Crucially, for many species, this could have serious implications for their future survival," the Trust said.

The survey also found high temperatures have pushed back many autumnal events, such as leaves changing colour and falling off the trees.

? The Woodland Trust is appealing for more people to join its survey. Recording forms are available at www.phenology.org.uk.