Temperature records have been broken across three continents this week, as heatwaves sweep across Europe, the United States and Asia simultaneously.
Along with warnings to stay indoors, close the blinds, and keep hydrated, scientists have said we should expect such conditions to become more common and potentially more intense in the future as a result of climate change.
The world has so far warmed 1.2C above pre-industrial temperatures, a factor that is driving the intensity of these heatwaves. It will continue to heat until emissions get to net zero.
Scientists have issued dire warnings that this may in fact be one of the coolest summers of the rest of our lives.
“This is just the beginning,” said Simon Lewis, chairman of Global Change Science, University College London.
“This is what the climate system can do at just 1.2C warming. Current policies globally have us hitting 2.7C warming by 2100. That’s truly terrifying.”
But how worried should we be, and what can we do?
Though climate scientists say heatwaves are expected to be more frequent and more intense with climate change, exactly how often they will occur is more difficult to predict.
Extreme heatwaves may be more likely in a year with an El Nino, a natural warming phenomenon that occurs every three to seven years.
But although we are at the start of an El Nino cycle now, scientists say its impact on this heatwave is minimal and the full force will not be felt until later this year.
The El Nino could also be mild, meaning next summer may not be as hot as this one.
When it comes to this year’s heatwaves, the UK appears likely to escape the worst of it.
The jet stream, a band of strong wind blowing east to west, is currently stuck somewhere south of the English Channel in a U-shape around the southern coast of the UK.
The result is low pressure and cooler Arctic air to the north of the jet stream, in the UK, and the opposite to the south in mainland Europe, where hot air is being drawn in from Africa.
Unsettled weather, which means rain and clouds, is expected at least until mid-August, when things could heat up a bit. But the Met Office says a 40C (104F) temperature is unlikely to be seen in the UK this summer.
For those going abroad, it is a different story.
In Greece, resorts have been evacuated as wildfires rage, while tourists have reportedly collapsed in Italy, where temperatures have reached as high as 44C.
The US and China are experiencing a heat dome effect, as stubborn high pressure traps heat in the atmosphere – causing temperatures to soar to 47C in Arizona, where a burns unit reported hospitalisations caused by people touching the pavement.
Excessive heat is dangerous if treated without caution and can be deadly. Last year’s heatwaves led to the deaths of 60,000 people in Europe, including 3,000 in the UK, according to scientists at the Barcelona Institute For Global Health and the French National Institute For Health.
Our bodies need to stay below an internal temperature of 37C to function well. At 42C, you start to see the signs of heatstroke.
“People with heart conditions, pregnant women, and generally the aged (above 65 years) should avoid travel at such times, or take added precautions,” said Malcolm Mistry, assistant professor in climate and geospatial modelling at the London School of Hygiene and Tropical Medicine.
Travel experts are already warning that holidaymakers could avoid Europe’s hotspots in the future, with planned summer trips to the Mediterranean region already down 10 per cent compared with last year.
There has been some suggestion that climate change could have a positive impact, particularly for the elderly who are most vulnerable to colder weather.
But that balance could change as warming becomes more extreme – even in the UK – and intense heatwaves become more common.
Like the cold, heat is a particular risk for the elderly and those with underlying conditions.
But it is also a risk to other groups, including outdoor workers in sectors such as agriculture and construction. This could lead to a dip in productivity if they are forced inside.
“I’m most worried about the impact of heat on pregnant women, young babies and children,” said Chloe Brimicombe, climate scientist and extreme heat researcher at the University of Graz.
“We see a rise in preterm birth as an outcome of pregnancy with exposure to extreme heat. And a rise in hospital admissions amongst all of these groups.”
Ilan Kelman, professor of disasters and health at University College London, said: “When we get too hot, our organs have trouble functioning, so we die.
“Dehydration is a big killer. Without enough fluids, again our organs cannot work properly.
“Although we are warm-blooded so that we burn calories to regulate our body temperature, we reach limits and summer UK temperatures are exceeding those limits.”
The good news is that there are things we can do. Preparedness is key.
“Although heatwaves kill thousands and are often called a ‘silent killer’, one positive is that the health impacts can be reduced,” said Dr Vikki Thompson, climate scientist at the Royal Netherlands Meteorological Institute.
“Simply communicating the risks can reduce health impacts considerably. Relatively simple measures such as adjusting work hours for outdoor workers, ensuring access to water, and providing public cooling centres can make huge differences to the impacts of extreme heat on human health.”
But the consensus is that we are not well prepared for the heat coming our way.
The UK in particular is poorly adapted to coming heat, according to a recent report from Oxford University. It found that the UK was “dangerously unprepared” for a significant increase in uncomfortably hot days that were likely to occur at 2C warming.
That means that a 40C day in the UK could be much worse than a 40C day in southern Italy.
“While temperatures are hotter in the south of Europe, the northern countries are less prepared for heat as they are less used to it,” said Daniela Schmidt, professor of earth sciences at the University of Bristol.
“Examples are the way houses are built, shutters in front of windows, or our behaviours such as avoiding sunlight during the hottest times of the day.
“Therefore the absolute temperature is not the only thing we need to consider.”
