Written By Simon Keat Bsc Phd

There is an ever growing body of evidence that supports the idea the earth is warming at an increased rate as a result of mans activities, especially the burning of fossil fuels. In the next 50 years it is predicted that most parts of the UK and Europe will warm by 3-5°C. One important predicted impact this will have is that species will shift their ranges towards the poles as the earth warms. A particularly notable example of this is the apparent sightings of great white sharks, typically from South Africa, off the coast of Cornwall and Devon this summer. Insects have also been following this trend of poleward range expansions with many documented examples of northerly range expansions in Europe.Damselflie

The small red-eyed damselfly has expanded its range over the last 30 years into northern Europe and in 1999 crossed the English Channel and became the first recorded example of a migrant damselfly establishing colonies in the UK. Since its arrival in Essex in 1999 this species has rapidly increased its range in the UK and can now be found at sites from Devon to East Yorkshire. It might seem obvious to assign the rapid range expansion of this species to global warming, however as with all scientific questions it may not be as simple as it initially seems.

In southern Europe the small red-eyed damselfly takes one year to complete its life cycle but a study of the life cycle of this species in the UK showed it had a 2 year life cycle. So it might be that this species has changed its life cycle, allowing it to expand northwards into cooler areas because its development has slowed to 2 years, not because of global warming. The point I’m trying to illustrate is that scientists must look carefully at the evidence before assigning it to a particular cause like global warming. There is also a counter argument that governments will only act when the evidence is overwhelming, so it’s in our interest to paint a worst case scenario picture to get action from the government.