Phenology is the study of recurring natural phenomena which is carried out by monitoring the arrival and departure of species in our environment. By noting relevant dates, we can try to work out whether any changes are as a result of climate change.  The UK Phenology Network, run by the Woodland Trust and the Centre for Ecology and Hydrology, has over 25,000 volunteers who send in observations from their local area, including several thousand young Nature Detectives. Observers note a variety of things, including when leaves fall off trees and the colour of these leaves. The ripening of autumn fruits is also recorded as well as the first and last sightings of certain birds, before and after migration.
With the help of phenology, evidence is beginning to mount that the climate is changing and these changes are having an effect on wildlife. Leaves on many trees are appearing earlier in the year and flowers normally reserved for spring are appearing in November and December. By recording observations on a daily, weekly or seasonal basis, it is possible to see how quickly the local environment is changing, or whether it is remaining unaffected. Jill Attenborough, from the Woodland Trust says we're certainly seeing changes in the UK. 'Spring is coming about two weeks earlier than it would have been 30-50 years ago and Autumn about a week later'. Many species are dependent on each other or in competition with each other in the natural environment and warmer temperatures mean some species are gaining an advantage over others. Jill Attenborough says this will lead to changes:  'Oak trees, horse chestnut trees and sycamore trees, are coming into leaf much earlier, than some of our neighbours, like ash and beech and are getting the advantage. I think we'll see a change in the composition of our woods'.
It isn't just trees which are affected though - insects are also responding to the changes. According to the Woodland Trust's study, caterpillars are responding faster to changes in temperature than the blue tits which depend on them, which could mean birds struggling to feed their chicks. So, there is evidence that our climate has already changed, but how do we know this is due to changes in temperature? Jill Attenborough says the records collected and historical information going back 300 years are set against temperature changes. 'There is a very clear response between plants and wildlife and temperatures so we're very sure it's climate change that's causing this'. The UK Phenology Network scheme will continue to collate results, through its volunteers. However, more helpers are needed to make the scheme more extensive throughout the country - their aim is to have a volunteer in each 10km grid square in the country. Volunteers are welcome from anywhere in the country, however are particularly needed in the west and north of Great Britain and in Northern Ireland. (The BBC is not responsible for the content of external websites)
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