Weathering the storm

It is the nation’s favourite topic of conversation. Whether we feel it is too hot or too cold outside, or there has been non-stop rain or not enough to keep our gardens alive, the Brits love to talk about the weather.

But putting aside debates about the next Bank Holiday being a washout or a scorcher, the changing climate is  an issue that has got the world talking.

This winter saw the most severe weather for this season in the UK for 30 years. The snow seemed almost endless, with reports of people being stranded in their homes or on motorways and schools being forced to close.

But even after the snow melted, the country soon faced a new challenge in the form of a volcanic ash cloud blown over from Iceland which grounded flights and left holidaymakers struggling to find a way home.

Trying to predict the unpredictable

The two events are the result of regionalised weather ‘eddies’ over the UK, which work  within global currents of air and affect our short and medium term climate.

Dr Ken Addison from the University’s School of Applied Sciences explains that within the last six to eight months, more northerly air has been brought down towards the British Isles than normal by the North Atlantic Oscillation (NAO), a climatic phenomenon which revolves around the precise location of low and high pressure systems in the Atlantic.

Its behaviour was behind the substantial clouds of ash which entered the European atmosphere, the harsh winter and also the relatively dry and good weather of late May and early June.

But how easy is it to predict the weather? The Met Office famously forecast a barbecue summer for 2009, only to be greeted by an extremely wet July.

Dr Addison says meteorologists use computer models to compare current trends against long term recordings to look at the probability of circumstances and weather types over a period. However, it is never 100 per cent certain, and is subject to change.

“Britain is at the equivalent of the spaghetti junction of some of the earth’s big weather systems. One of the most predictable things about our weather is that it is unpredictable,” Ken says.

Climate change

Climate change is high on international agendas, even though a global agreement at the Copenhagen Climate Change Summit in December 2009 fell short of what many countries including Britain had hoped. Notably, America President Barack Obama gave a speech to the United Nations earlier that year in which he said, “the threat from climate change is serious, it is urgent, and it is growing.”

Ken, who specialises in earth and atmospheric sciences, says: “What is involved here is the extent to which climate scientists can distinguish between long term natural climate variability and effects superimposed on this by human actions which change the energy and moisture balances of the atmosphere – most noticeably through what we call greenhouse gases.

“Most people are aware that earth has gone through a series of ice ages and interglacial periods and that weather can also be very variable from one year to the next but the science is now as certain as science ever can be that there is a marked human impact on climate. Without any mitigating actions such as large reductions in greenhouse gases, climate change may accelerate beyond a certain threshold to potentially catastrophic and irreversible consequences.”

Despite this,  there remains a level of public scepticism about climate change. Ken argues that some of the distrust results from the frequent short term changes in weather, such as recent particularly rainy summers. There was also a level of doubt about the integrity of scientific data just before the Copenhagen summit took place.

But Dr Addison, who has worked at the University for 35 years, says: “The uncertainty about the data has largely been dismissed and it is important that we get back to the impetus for concerted global action that was lost at Copenhagen.

“Most international governments accept the need for, and have targeted, large reductions in greenhouse gas emissions but there is currently no international political machinery capable of developing and enforcing worldwide action. Not only will we therefore delay in taking the mitigating actions but we will increasingly have to operate crisis management for climate induced disasters.”

Looking ahead

In the long term, Ken says the UK could find itself with a climate similar to the Canadian sub-Arctic region of Labrador, which is on the same latitude as the British Isles.

The Labrador Sea is filled with icebergs for eight months of the year, with cool winds and light rain and drizzle in summer while winter is characterised by severe sub-zero temperatures and frequent snow flurries.

But before you start reaching for your ice picks and snow tyres, Ken says that if this did eventually occur, it would not be until or beyond the end of this century. In the mean time, he believes we will experience the kind of warming that other parts of the world get – warmer summers that are generally drier but with more intense thunderstorms and milder winters which are probably a lot wetter.

One thing seems certain – the Brits will continue to debate, argue and complain about our unpredictable climate, whatever the weather.