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Friday 20 July 2018

Last 10 years wettest decade on record thanks to climate change

While the rainfall record over the last decade is among the most significant findings, the data also reveals that over the long-term, winters are getting wetter and summers drier.
While the rainfall record over the last decade is among the most significant findings, the data also reveals that over the long-term, winters are getting wetter and summers drier.

THE decade between 2006 and 2015 was the wettest on record, with 10-year average rainfall almost double that experienced over the past 300 years.

A new rainfall record for Ireland says the continuous rise in annual and winter rainfall is consistent with human-induced climate change.

Using UK and Irish data, senior geography lecturer in Maynooth University Dr Conor Murphy and colleagues found that average rainfall between 2006 and 2015 was 1,990mm per year.

This compares with an average across the three centuries of 1,080mm, and only 940mm between 1740 and 1749, the driest decade on record.

The record provides monthly rainfall totals representing the island for each month since January 1711, and means that Ireland now has one of the longest rainfall records anywhere in the world.

"The most recent decade was our wettest on record, and when we look at the long-term context we see a continuous rise in annual and winter rainfall," Dr Murphy said. "This is consistent with expectations of human-driven climate change.

"The fact that we have such a long rainfall record for Ireland is thanks to the meticulous work of weather enthusiasts and meteorologists from Ireland and the UK over hundreds of years.

"The record draws on the very earliest rainfall observations made in this region, together with weather diaries compiled during the 1700s."

While the rainfall record over the last decade is among the most significant findings, the data also reveals that over the long-term, winters are getting wetter and summers drier.

The driest winter on record is that of 1783-84, which coincided with the eruption of the Laki volcano in Iceland, which emitted millions of tonnes of sulphur dioxide into the air, creating what was called the "Laki haze". "This gave much of Europe an extremely hot summer, followed by a dry and severe winter," Dr Murphy said, adding that changes in rainfall have resulted in severe impacts here.

STORMIEST

"Recent wet weather has had significant effects on Ireland. Winter 2015/16 saw extensive flooding across Ireland, while winter 2013/14 was the stormiest on record.

"These winters, which not only took place during our wettest decade, are also the first and second-wettest individual winters on record."

There were warm winters too, including 1733 when a reference was made "to primroses and violets blooming at Christmas", according to the paper.

The UK Met Office originally stitched the data together in 1979, which was reported in an internal memo.

That record was merged with a dataset compiling weather in Ireland between 1850 and the present, and the combined information covers rainfall variations for every month between 1711 and 2016.

"We can not only see how rainfall has changed in Ireland, but also look at what was going on in the wider world to influence it," Dr Murphy said.

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