Ireland has warmed by half a degree in the last 30 years

Irish farmers struggle in the clutches of recent soaring temperatures – but should we have seen it coming in light of recent years?

In a recent interview with AgriLand, Prof. John Sweeney, Professor (Emeritus) of Geography at Maynooth University, cautioned that this “is the kind of thing that we would expect to see more commonly in the future”. 

According to Prof. Sweeney, the current warm spell in Ireland is as a result of warm winds coming from mainland Europe.

The air is coming off an ocean which is half a degree warmer than it was in recent years; mixing with a continent which is also half a degree warmer.

“It is not unusual to get a dry period in June, which is generally drier than July and August,” said Prof. Sweeney, “especially in the east of the country”.

However, something has changed; Ireland has warmed by “half a degree in the last 30 years”.

“While you cannot describe an individual event confidently as being due to climate change, what we can say, at this moment, is that those kinds of extremes are likely to increase because of what we are doing to the atmosphere” said Prof. Sweeney.

Drought history

When asked about the probability of the current heat wave becoming an annual occurrance, Prof. Sweeney revealed that we “have a drought history in Ireland”.

“Recently-reconstructed Irish rainfall patterns have revealed that droughts are more commonly occurring in Irish history than we thought,” said Prof. Sweeney.

For the past 40 years we have had a relatively drought-free Ireland by comparison to some of the more extreme events that were observed in the 18th and 19th century.

While the models for summer rainfall at this moment in time are relatively uncertain and un-definitive, Prof. Sweeney confirms that change is in store:

“When you look at the whole output models for summer rainfall in Ireland it suggests that summers will be drier in the future because the jet stream will have moved north.”

According to Prof. Sweeney it may be time for those in Irish agriculture to “think the unthinkable“.

He believes investment in irrigation and water-harvesting systems may be the next big investment for the sector.

‘Erratic’ jet stream

What exactly can be held responsible for a year of one extreme weather anomaly after another?

According to Prof. Sweeney, the answer lies with our increasingly ‘erratic’ jet stream. 

A jet stream is an area of strong winds between 10km and 15km that flow continuously from west to east in our atmosphere.

“The jet stream is becoming increasingly unpredictable over recent years; currently it is taking a route in the high Arctic, far to the north of Ireland and giving rise to what we call blocking anti-cyclones,” cautions Sweeney.

The weather phenomena – known as ‘blocking anti-cyclones’ – are large-scale patterns in the atmospheric pressure field that are nearly stationary, effectively “blocking” or redirecting migratory anticyclones.

The Atlantic has effectively lost control of Irish weather.

“It may be as a result of the warming of the Arctic that transpires as a weakening to the jet stream as it moves towards the north of Ireland,” said Prof. Sweeney.