Temperature records are being shattered everywhere, so why is Ireland’s from the 1880s?
Phoenix Park in Dublin recorded a temperature of 33.1C on Monday afternoon.
It was 135 years ago that the hottest day in Ireland's history supposedly took place, but doubts around the veracity of that record means this week's 33C in Dublin is almost certainly the true holder.
It was Kilkenny Castle in 1887 that saw a recorded temperature of 33.3C, since converted from the old Fahrenheit system. That has been used as the standard-bearer in the 135 years since, and is considered hallowed by Met Éireann.
Head of forecasting at Met Éireann Evelyn Cusack this week called the 1887 Kilkenny Castle record "sacred", and disputed questions around its accuracy. It is a "proper temperature", she told Newstalk's programme.
However, one of Ireland's leading climate change authorities, Prof Peter Thorne of Maynooth University, is convinced the 33C seen in Dublin's Phoenix Park this week is the true champion, albeit of an unenviable title in the context of a globally warming planet.
The professor of physical geography (climate change), who was a contributing lead author on the recent UN-backed International Panel on Climate Change (IPCC) reports, assigned a masters class in 2019 a project to robustly reevaluate and reanalyse the Kilkenny record.
Their findings were convincing, so much so that Prof Thorne said the 1887 temperature record was akin to a world record 9.50 seconds being run in the 100m Olympic race, but with race officials unsure if runners started at the actual white line or 60m down the track.
"One group looked at the instrument in Kilkenny Castle, what we know about it, how it was measured. One group looked at the weather going on at the time around the country, using very recent reanalysis products, that is retrospectively looking at it, back in time. The last group looked at comparisons of other stations.
"The station existed for decades, but the records were destroyed after three years because they were not deemed to be useful. So we only have in glorious isolation an observation of 33.3C following conversion from Fahrenheit, it is just one daily maximum taken in complete isolation from any time series.
"We know it was taken somewhere in Kilkenny Castle, but don’t know where in the grounds. We know from available documentation that it was taken in what is termed a Stevenson screen, which is the wooden screens in weather stations. It was likely liquid in a glass thermometer, because that was standard at the time. Those screens were smaller than they are today, and more susceptible to heating effects such as direct sunshine. There are many things we don’t know much about the site," he said.
The difference between the 1887 record and this week's Phoenix Park high of 33C is that today's records are taken using guidance and principles from the World Meteorological Organization (WMO). It is Prof Thorne's "100% certain contention" that this week was indeed the hottest recorded date in Ireland.
"The reanalysis, looking at historical and documentary data from 1887, showed there was no doubt it was hot at the time. The weather set-up was remarkably similar to the weather we had this week.
"But to me, the killer line is the comparison to other stations. We didn’t have anything like the same weather stations in 1887 that we have today.
"There are some stations that exist today, but at the time we had stations like Phoenix Park, Galway, Roches Point, and the likes of Sheffield. When you look at those stations, they all peaked on the day in the high 20s, none of them peaked in the mid 30s.
"It’s physically implausible Kilkenny could have been so different to other stations. It’s such an extreme outlier to modern daily differences. The record is not robust. I’m not saying it could not have occurred, but there is grossly insufficient evidence to support it," he said.
Met Éireann had not responded to questions around the 1887 record at the time of print.
Whether or not the record of 1887 is robust or not, it is inevitable in today's globally warming world that Ireland will soon exceed 33.3C, according to Prof Thorne.
"It is undoubtedly the case that we will break records with increasing frequency as we move forward, unless and until we stop using heat-trapping gases. What we have seen over the past few decades is the emergence of the signal of climate change from the variability of weather.
"We're just starting to see that with these extremes of temperature. Arguably, this is one of the first extremes of temperature in Europe that could not have occurred without human influence.
"The UK Met Office had an analysis a couple of years ago looking at the probability of exceeding 40C and it found that it was likely at some point this century. It was far closer than they thought, obviously.
"The conclusion was that it was effectively impossible without human influence that it would have happened once in a thousand, or even million, years."
Ireland is unlikely to see 40C, but it is not inconceivable, he said.
"I think we would have to have very considerable global warming to hit 40C here in Ireland, and only if we had a very dry summer, so that the vegetation was parched and the ground was very, very dry, and we had a set-up like this week. It would not be dynamically impossible to hit 40C, but it is very unlikely we would hit 40C in the foreseeable future.
"But if we are mad enough to continue on our current trajectory globally in terms of emissions, and I would caveat that if every person in the world had the historical emissions profile of Ireland, we would already be sitting pretty at 3C or so of global warming. We've played more than our part in warming to date.
"If we go 3C, 4C, 5C of global warming, then you would say all bets are off, but it would require significant factors to occur such as drying of soil and vegetation for us to hit 40C."
Britain surpassed the 40C mark for the first time this week, with Heathrow taking the previous hottest day title from Cambridge for a few hours, before 40.3C was recorded in Coningsby, Lincolnshire.
![Britain surpassed the 40C mark[/url] for the first time this week.](/cms_media/module_img/6233/3116924_25_articleinline_2.67954756.jpg.jpg "Britain surpassed the 40C mark[/url] for the first time this week.")
Dr Mark McCarthy, head of the Met Office National Climate Information Centre, said: “This week has been a remarkable week for the UK’s climate. We have seen temperature records tumbling. A new UK national climate temperature record should be a rare occurrence, and we would normally expect a new record to only exceed the previous one by a fraction of a degree.
“However, we saw 39 stations across a large swathe of England exceed the previous highest daily temperature extreme, with the highest exceeding the previous record — set in Cambridge in July 2019 — by a remarkable 1.6C."
The extreme temperatures in the UK are unprecedented in recorded history, according to Met Office chief scientist Professor Stephen Belcher.
"In a climate unaffected by human influence, climate modelling shows that it is virtually impossible for temperatures in the UK to reach 40C.
“Climate change, driven predominantly by accumulation of greenhouse gases in the atmosphere, has warmed the average climate by more than 1C. So, when we see atmospheric circulation patterns conspiring with the background warming, we experience even hotter conditions.
"Under a very high emissions scenario, we could see temperatures exceeding 40C as frequently as every three years by the end of the century in the UK. Reducing carbon emissions will help to reduce the frequency, but we will still continue to see some occurrences of temperatures exceeding 40C and the UK will need to adapt to these extreme events.”
The heatwaves that gripped Western Europe must now be seen as a "new normal", WMO secretary-general Petteri Taalas said.
"We will see stronger extremes. We have pumped so much carbon dioxide in the atmosphere that the negative trend will continue for decades. We haven’t been able to reduce our emissions globally. I hope that this will be a wake-up call for governments and that it will have an impact on voting behaviours in democratic countries," he added.
Temperatures in Europe reaching 50C are now inevitable if data from the EU's Copernicus Climate Change Service is any guide.
A previously unthinkable 48.8C became reality last summer, and with the intensity and frequency of this summer’s heatwaves across the continent, that record could be shattered sooner rather than later.
Asked by the if the temperature could exceed 50C in the near future in Europe, Copernicus senior scientist and report lead author Freja Vamborg said: “We’re not necessarily in the business of extrapolating into the future, mainly focusing on monitoring what has happened, but of course, as temperatures warm, not only are the average temperatures expected to increase, but so are the maximums.
"48.8C in not that far away from 50C, and the 48.8C was already 0.8C warmer than the previous European record. I won’t give a timeframe, but, for sure, this is not going to be the last temperature record we’ve seen in Europe.”
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