Why is the current weather out of kilter with climate change predictions

The UKCIP climate prediction model for Devon suggests that by 2080 summer temperatures will have risen by 4.5 degrees and summer rain will have declined by 52%.

This seems to make no sense when we have just had two summers of exceptional rain accompanied by lower summer temperatures.

Although this contradiction is not fully understood it is tied in with the jet stream. This is a high level stream of air which affects the weather in Western Europe. In normal years the jet stream comes in from North American crosses the Atlantic at around 12km and ends up in Scandinavia and Iceland and with it brings wet cool weather.

The reason Britain has been so wet over the last two summers is because the jet stream has been forced south and instead of the wet summer weather going to Iceland it has ended up here.

It is thought that one of the major reasons that the jet stream has been pushed south is due to a phenomenon occuring in the Pacific La Nina. This is part of the ocean atmosphere phenomenon known as El Nino. El Nino has two phases La Nina and El Nino - we are currently in the later phase and it is thought that once it switches back to La Nina the jet stream will head north once again.

When El Nino is prevalent heavy rain is experienced in South America, when itis reversed to La Nina then heavy rain is experienced further afield. For more details see the BBC Weather Centre.