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Hottest year in Ireland and rest of world could be surpassed again as El Nino peaks

Last year shattered global temperature records with largest jump ever recorded

Last year broke the record for the hottest year on record by a huge margin, providing “dramatic testimony” of how much warmer and more dangerous today’s climate is from the cooler one in which human civilisation developed, according to leading climate scientists.

Last year shattered the previous global temperature record by almost two-tenths of a degree – the largest jump ever observed. The planet was 1.48 degrees hotter in 2023 compared with the period before mass burning of fossil fuels and other polluting activities ignited the climate crisis, Copernicus Climate Change Service (CCCS) said on Tuesday.

The figure is very close to the critical 1.5-degree temperature target of the 2015 Paris Agreement, though the global average temperature would need to be consistently above 1.5 degrees for the target to be considered broken.

The warming pattern was matched in Ireland, which experienced its hottest year ever. The 2023 average temperature in Ireland was 11.2 degrees; 1.65 degrees above the 1961-1990 long-term average, according to Met Éireann figures.


The CCCS report highlights several record-breaking conditions, including the hottest month on record and daily global temperature averages briefly surpassing pre-industrial levels by more than 2 degrees. In addition, sea surface temperatures were at “persistently and unusually high levels”, particularly in the North Atlantic.

The primary cause of increased global heating was continued record emissions of carbon dioxide, assisted by the return of the natural climate phenomenon El Niño.

Climatologist Prof John Sweeney of Maynooth University said 2023 temperature anomalies were “not unexpected”. As the peak of El Niño conditions had not yet been reached, “temperatures could be similar, if not warmer this year”, he added.

Of concern, he said, was how close the world was to “the 1.5-degree threshold” with indications it would be exceeded for a few years, at best.

It was important to emphasise 1.5 degrees was the global average, he said, when other parts of the world were warming at a higher rate – by a factor of four in the Arctic, while Europe was warming twice as fast.

Met Eireann temp anomalies. Source Met Éireann

A big worry was that simultaneous extreme weather events might occur during summer months, which could impact on food systems, Prof Sweeney said. This could occur beyond tropical areas and include Ireland.

The Government’s new climate plan had many references to “extremely challenging”, which he believed was political speak for targets likely to be missed, “or for a lack of political will to achieve things” – when drastic actions were needed.

CCCS said it was likely the 1.5-degree mark would be passed for the first time in the next 12 months. The average temperature in 2023 was 0.17 degrees higher than in 2016, the previous record year, marking a very large increase in climate terms. Each month from June to December in 2023 was warmer than the corresponding month in any previous year – a similar trend was seen in Ireland.

High temperatures drove heatwaves, floods and wildfires, damaging lives and livelihoods across the world. Analysis showed some extreme weather, such as heatwaves in Europe and the US, would have been virtually impossible without human-caused global heating.

CCCS director Carlo Buontempo said: “The extremes we have observed over the last few months provide a dramatic testimony of how far we now are from the climate in which our civilisation developed.

“This has profound consequences for the Paris Agreement and all human endeavours. If we want to successfully manage our climate risk, we need to urgently decarbonise our economy while using climate data and knowledge to prepare for the future.”

Hundreds of scientific studies have shown the climate crisis is causing more extreme weather events but the frequency and intensity of such impacts has alarmed experts.

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Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times