Bluebells are blooming, horse chestnut tree flowers are out and everything is looking lush – and it probably comes as no surprise that this spring has come early thanks to unusually mild weather.
To gauge how early spring has arrived needs a long history pf observations, though, and is something that amateurs in Britain have excelled at for a long time. For example, since 1947 Jean Combes in Surrey has been recording the dates when the leaf buds open on her local oak, ash, horse chestnut and lime trees. Her records show a huge advance in the leafing dates over the past 67 years, and especially since the 1990s when very early springs started to become very apparent. Leafing is now about 25 days earlier than in the 1950s, which mirrors a rise in temperatures over the same period – an advance of about six days for every 1C increase in spring temperature.
Of course, climate change sceptics can jump on some freak cold and late springtimes, such as last year, and argue that this proves that the climate isn't changing. But last spring was something of an odd-man-out and historical records that go back even further, over 250 years, show an unmistakeable pattern of springs coming earlier as temperatures have risen in recent times.
The Nature's Calendar survey at the Woodland Trust continues to record the dates of natural events in both spring and autumn and is asking for volunteers to send in observations to their website at www.naturescalendar.org.uk
