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FACTCHECK

Debunked: It is misleading to claim that 30-degree heat is 'normal' during an Irish summer

Social media users suggest that climate change has been exaggerated in recent weather reports.

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A NUMBER OF posts on social media this summer have suggested that higher-than-usual temperatures in Ireland are part of normal weather patterns for this time of year.

The posts, which often compare temperatures this summer with weather from years gone by, suggest that climate change is exaggerated and that such extremes are a regular feature of Irish summers.

“I remember in my younger days having 3 months at a time with weather like this, it was called summer,” reads one post, which shows an image of Ireland with 30° on it.

Claims like this can be made innocuously or without knowledge of the full facts, as several people did in the UK in July by comparing hot weather to a heatwave in 1976.

However, the same arguments are also used by climate change deniers who spread misinformation about the crisis now facing the planet.

Since the start of the summer, climate sceptics have taken to social media to share data or weather charts comparing extreme temperatures this year to those allegedly recorded years or decades ago.

These figures are often incorrect or taken out of context – and even when accurate do not change the fact that heatwaves are becoming more frequent and intense.

Such claims have been debunked or given context by fact-checkers in the UKSpain and Germany in the past month alone.

Similar tactics are now being used in Ireland, with comparisons to previous summers being taken out of context to downplay the impact of climate change on how warm it has been this year.

‘Exceptional’ summer

Looking at the statistics alone, it is clear to see that the warm weather across the northern hemisphere this summer is far from normal.

Temperature records have been broken across multiple continents, at a time when long-term meteorological trends indicate that the planet is getting hotter.

While warm weather at this time of the year is not unusual, and has been recorded in the past, its intensity is in line with warnings from experts that climate change is amplifying extreme weather events.

Experts say that Ireland has seen an exceptional summer this year, driven by climate change spurred to human activity.

And while extremely hot weather does occur within natural climate variability, the evidence shows that the hotter-than-usual weather we’ve experienced is far outside the margins of what could normally be expected.

On 18 July, Met Éireann’s weather station at the Phoenix Park in Dublin recorded a temperature of 33 degrees Celsius, Ireland’s highest temperature since 1887 and the second-highest ever recorded on the island – with suggestions it may even be the highest.

It was 12.8 degrees above the long-term average for the Phoenix Park  – the average temperature at the station at that time of year between 1981 and 2010 – of 20.2 degrees.

A temperature that high had never been recorded in Ireland in July, nor in the entire 20th century or the 21st century until that point.

Record high temperatures were also recorded at nine synoptic stations and across many locations in Ireland.

Yesterday, Oak Park in Co Carlow recorded a temperature of 31.7 degrees, beating the previous all-time August temperature record for Ireland of 31.5 Celsius, which was set in 1975.

The previous day, a maximum temperature of 30.4 Celsius was recorded at the same station – the first time the 30-degree mark had been breached in Ireland in August since 2003. 

Met Éireann reported that it was the first time Ireland has experienced temperatures above 30 degrees in two summer months since 1995, and the first time temperatures have risen above 30 degrees during two consecutive summer months since 1976.

Emeritus Professor of Geography at Maynooth University John Sweeney explained that such high temperatures this summer have been primarily driven by climate change.

“We haven’t had a July with temperatures above 33 degrees Celsius before,” he told The Journal.

“And the evidence points increasingly to the fact that these kinds of heat wave events are occurring in greater intensity and greater frequency by climate change.

“There’s a recent report on the July heatwave in England which indicates that it was ten times more probable to have occurred as a consequence of climate change.”

On the same day that Ireland’s highest temperature of the year was recorded, eight other stations across the country also recorded their highest-ever temperatures, all of which were more than 10 degrees above their long-term averages.

For context, summer temperatures in Ireland usually only reach the high 20s and only rose above 30 degrees in two or three years in each of the last few decades.

At no point were such temperatures normal – they were very much an anomaly until the last decade or so, during which they have become much more frequent.

Temperatures have already risen above 30 degrees in two years in the current decade (2022 and 2021), as well as five times in the past ten years (2022, 2021, 2018, 2016 and 2013), where previously this only happened three or four times in a ten-year spell.

Aside from the fact that high temperatures occur during temporary spells, rather than for the entire summer, Ireland has been getting gradually warmer in recent years too: since 1990, the country has recorded six of its ten warmest years ever.

The annual average surface air temperature has risen by nearly 1 degree since the start of the 20th century, and experts say the country is at least 0.5°C warmer than average conditions between 1961 and 1990.

Global patterns

This summer’s high temperatures are also occurring in the wider context of similar weather patterns across the world, with several countries experiencing record-breaking heatwaves in Europe, North Africa, the Middle East, and Asia.

Western Europe is experiencing one of its hottest and driest summers on record, with wildfires, excess deaths and water shortages reported across Spain, France and Portugal.

After Ireland recorded its highest temperature since 1887, the UK reached 40 degrees for the first time, while Wales and Scotland also posted their highest-ever temperatures.

Speaking to The Journal at the time of the July hot spell, postdoctoral researcher at Maynooth University Dr Clare Noone said the weather is evidence of the effects of a changing climate.

“As the planet warms, the extreme heat now begins earlier in the year and stretches later, so heatwaves are getting longer, stronger and more frequent and that’s due to climate change and our usage of fossil fuels,” she said.

“We’re seeing record breaking temperatures, and we’re also seeing climate induced air pollution that impacts health and devastating wildfires. This is just the pattern and it will continue to get worse for as long as we continue to burn fossil fuels.”

Dangerous heatwaves have occurred in Europe in the past, but studies suggest that these are becoming more frequent.

A recent study in Science found that a person born in 1960 will only experience four major heat waves in their life, while a child born in 2020 will experience 18, even under the target to keep global temperatures to 1.5 degrees above industrial levels by 2100.

“There are people that keep talking about how we had heat waves in the past and so on, and yes we did, but we didn’t have the same drivers that we have at present,” Professor John Sweeney added.

Increasing in intensity and frequency

“And there’s an idea that these things are natural, but they are being driven increasingly in terms of the intensity and frequency by what we’re doing to the atmosphere.

“We have already warmed up the atmosphere by 1.5 degrees Celsius, so there’s no justification anymore for saying that heatwave frequency and intensity is not controlled by human climate change.”

A spokesperson for Met Éireann’s climate services division echoed this, explaining that temperature extremes which currently being seen in Europe are directly influenced by climate change.

“There are a large number of studies showing that human induced global warming has increased the likelihood of extreme events occurring across the planet,” a statement said.

“We can now say, for example, that when we have a heatwave or drought it is scientifically correct to point to the increased risk of such events due to human activities.”

The spokesperson added that, as the study of attribution of individual weather events has greatly advanced in recent years, it is no longer appropriate to say that a single event cannot be attributed to climate change.

It is now possible to frame events like the recent warm spells as having a greater probability of occurring due to climate change, and to say they are most likely part of a trend of increasing extreme weather events.

The suggestion that this year’s warm weather is similar to summer’s gone by and not linked to climate change is therefore inaccurate.

Contains reporting by Jane Moore and © AFP 2022.

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