Climate change shifting European seasons
Pastor Dale Morgan
Climate change shifting European seasons*
David Fickling
Friday August 25, 2006
Guardian Unlimited
Spring is arriving sooner and autumn is starting later because of
climate change, according to a study of more than 500 plants and animals
across Europe.
Scientists found that events associated with the start of spring - such
as the flowering and leafing of plants and activities of certain animal
species - were now appearing six to eight days earlier across the
continent than they did 30 years ago.
Britain saw an even more dramatic change, with spring events happening
10 days earlier and particular species seeing even earlier flowerings.
Wild cherry trees are now flowering two weeks earlier than they did in
the 1970s, the report found.
The study of 542 plants and 19 animals from 1971 to 2000 found 78% of
plants flowering, leafing and fruiting earlier, with only 3% waiting
longer before the spring change.
There was also a marked delay in the arrival of autumn, which arrived an
average three days later across the 21 countries surveyed.
Tim Sparks, the UK researcher who co-led the study, said that the change
in seasonal dates could disrupt the ecological cycles of many species,
as average temperatures rise by 2-5C or more over the coming century.
"There's a limit to how much earlier these events can get without
affecting some of these species. Trees need a rest period during the
winter, and if leafing starts happening earlier, that period becomes
shorter," he said.
Migratory cuckoos, whose arrival has long been one of the traditional
signs of spring, can also be affected by the changes, as the insects
they feed on and the plants that the insects feed on start emerging
earlier in the year.
But Dr Sparks said that a 30% decline in the population of British
cuckoos meant that they were no longer a reliable marker of the season,
and spring-watchers were better off listening out for swallows.
People in Britain may be surprised to learn that the summer season is
getting longer after this year's severe winter and dreary August, but Dr
Sparks said that weather over the past month has actually been more
typical of the historical average.
"We've become accustomed to much warmer years recently, and I think
we're probably so overwhelmed by the temperature in July that when
August returned to the rather unimpressive summers that Britain usually
has, everyone was surprised," he said.
He said there was no sure rule of thumb for the start of spring from the
flowering and leafing events seen in the UK, with even early flowers
such as snowdrops and wood anemones showing markedly different flowering
dates in different parts of the country.
Traditionally, spring starts on March 21 with the vernal equinox, the
point at which day and night are of equal length and the day starts
lengthening towards the summer solstice. But the Met Office caused
irritation this year when it attempted to tidy up the seasonal calendar
by announcing that the official start of the season would by March 1.