Across the Northern Hemisphere, a pattern of heatwaves peppered by extreme temperatures, largely related to human-caused climate change, has taken hold.
Within Europe that trend is more striking, as extremely hot days are now about 2.3 degrees warmer than in 1950. This is an increase of 0.33 degrees per decade, greater than the average global warming of about 0.2 degrees every 10 years.
Nine out of the past 12 years were among the warmest years on record since 1850 – a pattern broadly similar to the one experienced in Ireland, though we have avoided the temperature extremes seen on the Continent.
Yet, Ireland had its highest temperature in 135 years on Monday, 33.1 degrees, and has particular vulnerabilities in being less prepared for extremes than many European countries.
A study led by the Potsdam Institute for Climate Research in Germany, published in Nature Communications earlier this month, outlined what may be the reason why Europe is outpacing the planet’s overall warming trend. Heatwaves over the past 42 years are increasing in frequency and intensity in Europe at a faster rate than almost any other part of the planet, including the western United States.
It linked this increase, at least in part, to changes in the jet stream which flows around the globe some 10km above the Earth’s surface. The study points to stubborn changes in atmospheric circulation.
The researchers found that many European heatwaves occur when the jet stream has temporarily split in two, leaving an area of weak winds and high pressure air between the two branches which is conducive to the build-up of extreme heat.
Western Europe has seen a sharp increase in heatwaves, with the frequency of such events increasing three to four times faster than other parts of the Northern Hemisphere.
The research acknowledges natural climate variability, changes in one of the world’s major ocean currents – the Atlantic Meridional Overturning Circulation – and warming in the Arctic may be contributing to this.
And, unfortunately, heatwaves also beget heatwaves. When there is some moisture in the soil, some of the sun’s energy is used in evaporating the water, leading to a slight cooling effect. But when one heatwave wipes out almost all the soil moisture, there is little left to evaporate when the next wave of hot air arrives. So more of the sun’s energy bakes the surface, adding to the heat. Likewise, warmer sea temperatures lead to warmer temperatures over land.
Attribution science is providing great clarity on the likelihood of extreme weather events being made worse by human-caused climate change. A World Weather Attribution study shows it ratcheted up the odds and severity of the record-shattering heatwave in India and Pakistan since March.
Europe’s sweltering summer
Last month saw two serious heatwaves in Europe, during which monthly and some all-time temperature records were broken – with temperatures of 40-43 degrees common from Spain to Germany.
Towards the end of June and into this month, another heatwave stretched from northern Africa to the northern tip of Scandinavia. Many parts of Spain hit 45 degrees; in Portugal it was 47 degrees. The current plume of hot air concentrated on the western side of the Continent is finally shifting north, heading towards Britain on Tuesday, which was set for its hottest day on record. Temperatures in Belgium are forecast to exceed 40 degrees this week.
This heat has contributed to a deadly glacial avalanche in the Dolomite Mountains; wildfires burning out of control and hundreds of excess deaths due to extreme heat.
Prof Richard Allan of the University of Reading explained what is happening on the ground. “Summer heatwaves are usually caused by an extended period of dry, sunny conditions, usually associated with high pressure that snuffs out cloud formation,” he said. “Because there is little soil moisture, the sun’s energy heats the ground and the air above rather than being used up evaporating water. Higher temperatures and drier soils due to human-caused climate change are turning strong heatwaves into extreme or even unprecedented heatwaves.”
Heating from greenhouse gas emissions makes the atmosphere warmer and more thirsty for water, which can parch and scorch one region and deluge the larger amounts of moisture in storms elsewhere.
Extreme temperatures across Europe are the new norm. A pattern of rolling heatwaves, distinguished by longer duration and yet more record temperatures, is exactly as climate scientists predicted. It heightens health risks, makes it more difficult to control wildfires, lowers productivity and exacerbates food losses.
All this will force lifestyle changes and radical changes to water usage, while the spectre of an inability to grow food in much of the Iberian peninsula and around the Mediterranean may in coming years be a reality.
Ireland may avoid the more acute impacts, benefiting somewhat from the cooling of the Atlantic ocean, but the temperature curve is only going in one direction. Drought and water restrictions are the inevitable consequence. Temperatures breaching 35 degrees may be our new norm – arguably with less ability to mitigate the effects in managing buildings, agricultural production and water management.
The UK’s Climate Change Committee warned last year that the UK government was failing to protect people from a fast-rising risk. “Alarmingly,” its said, “the gap between the level of risk we face and the level of adaptation under way has widened. Little preventative action is being taken to address health risks from overheating in buildings, and in homes in particular.”
A similar scenario is likely to arise in Ireland. This is all about adaptation, preparing and building resilience for the inevitable impacts of climate disruption and heat extremes. We cannot just cope as we have with previous hot spells, as we have entered uncharted territory, with frequent extreme temperatures over prolonged periods.
“We’ve got a very severe heatwave at the moment and all the evidence that we have is that they’re going to get worse,” said Prof Nigel Arnell of the University of Reading. “Our services and infrastructure are designed to cope with ‘normal’ weather, and many organisations have plans in place to deal with what they think of as ‘extreme’ conditions. However, we’re seeing more and more examples of extremes, and we’ve also seen evidence that we’re not as well prepared as we thought.”
This means ensuring emergency plans are fit for purpose and that we can act promptly upon Met Éireann warnings.
“But we can’t keep on dealing with extremes in crisis mode. They’re happening more and more frequently, so we need to improve our resilience to extreme weather events. This means not only making sure new buildings and infrastructure are designed to cope with a changing climate,” Prof Arnell said.
Just as we have to insulate homes to retain heat in winter, heat-proofing buildings is equally important. This will help us deal with rising energy bills in winter too. It also requires building in more greenery in cities to lower temperatures. “We will only make real progress when adaptation and resilience is given a high enough political priority,” he said.
Ireland’s Climate Change Advisory Council has said increased frequency of severe weather conditions such as the current heatwave has demonstrated the need for urgent action on adaptation to ensure society has the infrastructure and services in place to respond to the impact that climate change is having on society.
The bottom line is the extent of heat in Europe and Ireland – albeit over just a few days – would be extremely unlikely without human-caused climate change.
“We have been warned for decades of this lethal consequence. Since air conditioning cannot be available for everyone, the only way now to avoid this level of heat is to stop warming the planet,” according to Ilan Kelman, professor of disasters and health at University College London.
That means cutting carbon pollution in the form of emissions and getting off fossil fuels rapidly.