2019 was the summer that tipped the scales on how we talk about our climate.
As temperatures smashed through record after record, the warnings came too - with the UN stating that the world needed to increase its efforts between three and five-fold to stand a chance of containing climate change.
The Arctic caught fire, hundreds of people in Iceland held a funeral for a shrunken glacier, and protesters took to the streets in cities around the world. And those who, by their own admission, were once complacent, revealed they had changed their minds.
Caring about the climate was suddenly cool, and celebrities in their dozens, whether via social media or on the red carpet, praised the efforts of the activists and started to join the pleas for real change from those in power.
At the end of a blazing July came the reports showing just how hot that month had really been – news of a temperature spike was no longer celebrated as a simple ‘summer scorcher’ by the media, but rather characterised by stories of very real fears around the rising mercury.
But how hot was it really? Were those days that left us sweltering just a series of random events, or have we entered an age where super-hot summers will now become the norm? Was it, as UN chief Antonio Guterres said, “not your grandfather’s summer”? And what happened in the part of the world supposedly experiencing winter?
We take a look at what science has to say about the summer of 2019.
The global picture
“Watching the summer unfold was very bad and we were very scared about it,” said Hannah Cloke, a hydrology professor and physical geographer at the University of Reading.
“Suddenly we were seeing all of the records falling again and again. The situation is very, very serious – some of the computer models we run were not picking up certain changes and we were left thinking ‘this is much worse than we expected it to be, what else could be coming around the corner?’”
The broader data shows that it was warmer than average. It was the northern hemisphere’s joint warmest summer on record, matched only by the summer of 2016, according to statistics based on average temperatures released by the US-based National Oceanic and Atmospheric Administration (NOAA) in mid-September.
Global temperatures were also at their third highest levels ever in the June-August period, at 0.94C above the 20th century average, standing behind only 2016 and 2017, according to the NOAA.
July 2019 was the planet’s warmest month on record, with summer records smashed across the northern hemisphere, and both the Arctic and Antarctic sea ice levels plummeting to historic lows.
August 2019 was the second warmest since records began, tied with 2017 and 2015, and lagging behind only 2016.
“There is a pattern,” Hannah Cloke said.
“Even if next year we didn’t see so many effects happening or the year after, I would still be completely convinced that we are on a trajectory into a dangerous place because that’s the way that climate systems move.
“We’ve got to have a long term perspective.”
How hot was the UK?
Britain’s record-breaking heatwaves were covered by much of the press in the same way as a Team GB athlete smashing a world best.
But as the mercury soared to 38.7C at Cambridge University Botanic Garden on July 25, the country’s highest ever recorded temperature – the warnings also came – “stay out of the sun between 11am and 3pm”, “check on your neighbours”, “wear loose-fitting clothes”.
And it wasn’t just the news outlets who were obsessed. Google Trends, which tracks the frequency with which phrases or words are entered as search terms, shows a huge fixation from the public on the soaring temperatures.
Throughout 2019′s heatwave period (July 21-27), searches for ‘UK heatwave’ reached an all time high, tracing back through Google’s data beginning in January 2004.
A month on and the UK found itself in the midst of another heatwave, the nation’s hottest ever late August bank holiday with temperatures climbing to 33.3C at Heathrow.
Despite the record highs, it wasn’t the hottest summer we’ve experienced. In fact, it was the twelfth warmest on record since 1910 according to date from the Met Office with an average temperature of 15.2C – 0.8C above the long-term average as recorded between 1981-2010.
The nation with the warmest mean temperature recorded was England at 16.3C, Wales in second with 15.1C, Northern Ireland at 14.5C, and Scotland at 14.5C.
The UK’s summer 2019 was notable not just for record-breaking heat however, but also for rain.
It was the seventh wettest since records began, with some counties such as Cheshire and Northumberland exceeding 170% of average rainfall, and residents in the Derbyshire town of Whaley Bridge evacuated after a breech in the nearby dam threatened to consume their homes.
While the methodology behind climate change and temperature has long been thoroughly established, Met Office meteorologist Grahame Madge explains, it is harder to tell how weather events such as extreme rainfall are linked with a warming planet.
“What we do know is that warm air holds moisture more effectively than cool air, which certainly indicates that we are likely to see more of these spells of very intense rainfall as the temperature rises,” he said.
“Computer models run by meteorologists at the Met Office for the next 50 years show that summers will be warmer, with rain taking the form of more concentrated downpours.
“We are expecting to see weather events such as the rain we saw in Boscastle in 2004 repeated with increasing frequency over the next few decades.”
What happened in Europe?
As the UK sweltered, so did vast swathes of Europe. Record temperatures were broken across the continent – the town of Lingen saw new record high for Germany of 42.6C set on July 26 and the southern France village of Villevielle recorded 45.1C on June 28.
The Netherlands, which since records began had never surpassed the 40C mark, saw 40.7C on July 25 in the southern municipality of Gilze-Rijen.
The heatwave which settled over Europe at the end of July was caused by the arrival of hot air from North Africa, Met Office meteorologist Grahame Madge explains.
“Although summer 2018 and 2019 were both very warm, the pattern we saw this year of extreme spikes in temperature and 2018′s lengthy heatwave were very different,” he said.
“The heat in 2018 was largely homegrown, with factors such as dry soil and clear skies exacerbating what meteorologists call a blocking pattern, which is essentially when a pressure system becomes trapped by other systems.
“What we saw in 2019 was extremely warm air coming up from North Africa which, when combined with other factors, caused these record breaking temperatures and a pattern consistent with a warming climate.”
On average, Grahame said, the planet has warmed by 1C since pre-industrial levels – but that increase has not been distributed evenly across the globe.
The UK has fallen in line with this average, with an increase of 1C, but in places such as North Africa the average temperature has risen by 2C.
“What it means is that the air travelling from North Africa, which would already have brought a spike in temperature in Europe, is warmer before it even arrives.
“When that is combined with conditions such as dry soil which we have seen in the UK for example, that increase of 2C in North Africa drives up the temperature and creates these relatively short-lived but very intense conditions.”
What’s happened in the rest of the northern hemisphere?
With the majority of the world’s land mass concentrated in the northern hemisphere, there was of course variation to be found in localised temperature records – but that didn’t mean it wasn’t warmer than average as a whole.
Even a quick look at a global map created by NOAA, showing the percentile deviation from average August temperatures worldwide, reveals that the areas which were cooler than average or even close to average were far outnumbered by weather stations which recorded warmer than average, much warmer than average, or record warmest temperatures.
One of the planet’s most varied nations this summer, climate-wise, was the US, which saw average or cooler-than-average temperatures across much of the central and northern areas, but some extreme highs in the south and along the country’s coast.
Analysis from NOAA shows us that, as a general rule, the eastern, western, and southern edges of the country saw the majority of above-average to much-above-average temperatures, whilst central areas remained around average, or slightly below average, for the summer season.
Some regions experienced temperatures which far exceeded the average. For example the statewide average for Alaska was 12.5C, 2.28C warmer than average, making it their second warmest summer on record.
Karin Gleason, a meteorologist at NOAA’s National Centers for Environmental Information, said that the US summer on the whole fell within the upper third of temperatures recorded over the past, “on the warmer side of average”.
Although Karin explained that her work at the NOAA was not involved with attributing weather patterns to factors such as climate change, she said: “We do know that in a warming world we are going to see more instances of warmer temperatures and records being broken – the whole distribution will shift to the warmer side so you tend to have more warm records and fewer cooler records.
“Certainly over the summer for the northern hemisphere there were a lot more warm records being broken so that would be consistent with a warming regime.”
This summer saw “unprecedented” wildfires in the Arctic region – freak weather events which are usually associated with periods of prolonged drought in forest regions.
The three largest economic losses on record from wildfires have all taken place in the past four years, the World Meteorological Association (WMO) reported.
In June 2019 alone Arctic wildfires released 50 megatons of carbon dioxide into the atmosphere – more than was released in Arctic fires in the same month from 2010-2018 combined.
Parts of Asia also experienced record-breaking temperatures, with the continent as a whole 1.1C above the 1910-2000 temperature as recorded by NOAA.
The Japan Times reported that in July more than 80 people died in a period of extreme heat, which saw a new national record of 41.1C set in Kumagaya, approximately 40 miles north of Tokyo.
India also experienced one of its most prolonged and intense heatwaves in recent decades, with a new 48C record being set locally in Delhi on June 10 and temperatures surpassing 50C in some regions – killing at least 36 people, according to the New York Times.
Africa, which as a continent straddles the equator and therefore, regionally, experiences both summer and winter throughout the season, had its warmest ever June-August with a temperature anomaly of 1.49C warmer than the 1910-2000 average.
Hannah said: “The idea that just because it’s flooding, or there’s a heatwave, or a snow storm, that doesn’t mean there’s climate change – but it’s the fact there are more, and they are worse, which is the worry.
“I work with global systems, and we’ve found ourselves waking up at six in the morning to look at what natural disaster has happened in the world that particular morning.
“If we don’t notice them, we can’t prepare for them. This heatwave, no one was prepared. We’re behind already, and we need to catch up.
“Infrastructure needs to change but also mindset – we’re not going to get any infrastructure sorted out until we’re all on the same page.”
What happened to the southern hemisphere’s winter?
As the northern hemisphere sweltered through a record-breaking summer, the southern hemisphere were experiencing their winter season – but that didn’t stop the unseasonably warm temperatures making their presence felt.
As a continent, Oceania had its 14th warmest winter, with temperatures across June-August an average of 0.75C above the 1990-2000 average.
Daytimes in particular were found by the Australian government’s Bureau of Meteorology to be above average, with the national mean maximum temperature to be the sixth-warmest on record for Australia (1.17C above average) and the mean minimum temperature to be 0.26C warmer than average.
The high temperatures followed extreme heatwaves across parts of the southern hemisphere in the preceding summer.
Record breaking heat in November 2018 – when Cairns recorded its highest ever temperature of 42.6C – led to the deaths of some 23,000 heat-stricken bats in just two days, wiping out almost one-third of Australia’s spectacled flying fox population.
New Zealand’s National Institute of Water and Atmospheric Research also ranked winter 2019 as their seventh warmest on record, with the season’s highest temperature of 21.6C recorded in Wakanui on July 3.
As a continent, South America saw a temperature anomaly of 1.29C above average from June to August 2019.
In 2017, the Bulletin of the American Meteorological Society (BAMS) released their first report setting out extreme weather events that scientists said could not have happened without the impact of human-induced climate change – something of a turning point in the way the scientific community spoke about attribution.
At the time, Jeff Rosenfeld – BAMS editor-in-chief – said that the report marked “a fundamental change.”
He said: “For years scientists have known humans are changing the risk of some extremes. But finding multiple extreme events that weren’t even possible without human influence makes clear that we’re experiencing new weather, because we’ve made a new climate.”
Summer may be over, but the latest Copernicus figures show that temperatures over Europe remained above the 1981-2010 average for the duration of September and 0.57°C warmer globally above the average temperature.
Temperatures over land masses in the northern hemisphere were also markedly above average over parts of the Arctic, over most of the USA, and over Iran, Afghanistan, Mongolia and northern China.
As the southern hemisphere heads into spring, temperatures were likewise above average over central South America, South Africa, south-western Australia and West Antarctica.
At this very moment, Extinction Rebellion are settling into the streets of London and preparing to occupy parts of the city for the next fortnight in a bid to keep the minds of world leaders focused on the climate crisis at hand.
Perhaps now more than ever, we are seeing an evaporation of the stereotypes around climate change campaigners – just weeks ago millions of people walked out of their daily routines and into the streets in order to demand action.
“It’s easy to see things on a three-year, five-year political cycle, but this is not of that scale,” said Hannah, who has spent years researching natural disasters in order to develop early warning systems.
“You have to look beyond the political cycle – it’s always really tough, and I appreciate that, but this is too important.
“We’ve been saying the same things for a long time. Finally being listened to would be quite good, and not only being listened to, but being listened to the people who will make decisions.
“The changes people are making in their everyday lives are great, but if we don’t have the decision makers at the top saying that this is a priority – that in 20 years our economy will be severely damaged by climate change, our wellbeing as a species – and if we are still not listened to then we really will be in trouble.”