Italy put 23 cities on red alert with temperatures set to reach up to 46 Celsius (114 Fahrenheit) on Wednesday, one of the global hotspots as a wave of extreme heat, wildfires and flooding wreaks havoc from the United States to China.
The heatwave has hit southern Europe during the peak summer tourist season, breaking records including in Rome and bringing warnings about an increased risk of deaths.
The Lazio region, focused on Rome, said it had seen a 20% increase in medical emergencies over the same time last year because of the heat.
Wildfires burned for a third day west of the Greek capital Athens and firefighters worked throughout the night to keep flames away from coastal refineries.
Fanned by erratic winds, the fires have gutted dozens of homes, prompted hundreds of people to flee and blanketed the area in thick smoke. Temperatures could climb to 43C on Thursday, forecasters said.
In China, which was hosting US climate envoy John Kerry for talks, tourists defied the heat to visit a giant thermometer showing surface temperatures of 80C.
In Beijing, which set a new record as temperatures remained above 35C for the 28th day in a row, Kerry expressed hope that cooperation to combat global warming could redefine troubled ties between the two superpowers.
A global pattern of heatwaves that scorched parts of Europe, Asia and the United States this week has thrown that challenge into sharp relief.
Temperatures remained high across much of Italy on Wednesday, with 45-46C expected on the Mediterranean island of Sardinia.
The health ministry said it would activate an information hotline and teams of mobile health workers visited the elderly in Rome.
"These people are afraid they won't make it, they are afraid they can't go out," said Claudio Consoli, a doctor and director of a health unit.
Carmaker Stellantis said it was monitoring the situation at its Pomigliano plant near Naples on Wednesday, after temporarily halting work on one production line the day before when temperatures peaked.
Workers at battery-maker Magneti Marelli threatened an 8-hour strike at their central Italian plant in Sulmona. A joint statement by the unions said "asphyxiating heat is putting at risk the lives of workers".
While the heatwave appears to be subsiding in Spain, residents in Greece were left surveying the wreckage of their homes after the wildfires.
"Everything burned, everything. I will throw it all," said Abbram Paroutsidis, 65.
Not everyone went willingly. Footage by Greek police showed officers imploring a reluctant group of nuns to evacuate a convent.
Scientists have long warned that climate change, caused by greenhouse gas emissions mainly from burning fossil fuels, will make heatwaves more frequent, severe and deadly.
In Germany, the heatwave sparked an unlikely discussion on whether workplaces should introduce siestas for workers.
El Corte Inglés, one of Spain's largest department store chains, said sales of air conditioning units had jumped, as had interest in cooling pads for pets.
"The current extreme heat is due mainly to a slow-moving anticyclone, a high-pressure system, that is dominating the upper atmosphere over southern Europe," explained Florian Pappenberger, Director of Forecasts at ECMWF.
"While the current heatwave is expected to last until around 26 July, another period of extreme temperatures may follow if the heat dome persists."
Heat and floods in Asia
In South Korea, heavy rain has pummeled central and southern regions since last week. Fourteen deaths occurred in an underpass in the city of Cheongju, where more than a dozen vehicles were swamped on Saturday when a river levee collapsed. In the southeastern province of North Gyeongsang, 22 people died, many from landslides and swirling torrents.
In northern India, flash floods, landslides and accidents related to heavy rainfall have killed more than 100 people since the onset of the monsoon season on June 1, where rainfall is 41% above average.
The Yamuna river reached the compound walls of the Taj Mahal in Agra for the first time in 45 years, submerging several other historical monuments, and flooded parts of the Indian capital.
The Brahmaputra river, which runs through India's Assam state, burst its banks this month, engulfing almost half of the Kaziranga National Park - home to the rare one-horned rhino - in waist deep water.
A wall collapse from monsoon rains killed at least 11 construction workers in neighboring Pakistan.
In China's western Xinjiang province, tourists with broad-brimmed hats and umbrellas took selfies by a giant thermometer that displayed a real-time surface temperature of 80C (176 Fahrenheit).
Each summer, people flock to the Flaming Mountains on the northern rim of Xinjiang's Turpan Depression to see their corrugated slopes of brown-red sandstone and to take in the super-charged heat emanating from the ground.
In recent days, temperatures in Xinjiang and other parts of Asia, as well as Europe and the United States have shattered records.
On Sunday, a remote township in the Turpan Depression registered a maximum air temperature of 52.2C, smashing China's national record of 50.3C set in 2015, also in the basin.
Iraq's southern Basra governorate, with a population of around 4 million, said government work would be suspended on Thursday as temperatures hit 50C. In Iraq's northern city of Mosul, farmers said crops were failing due to heat and drought.
Extreme heat in parts of the world will likely be exacerbated by the return of the El Nino weather pattern in the tropical Pacific for the first time in seven years, which is expected to push up temperatures.
The unprecedented temperatures have added new urgency for nations around the globe to tackle climate change.
With the world's two biggest economies at odds over issues ranging from trade to Taiwan, Kerry told Chinese Vice-President Han Zheng on Wednesday that climate change must be handled separately to broader diplomatic problems.
"It is a universal threat to everybody on the planet and requires the largest nations in the world, the largest economies in the world, the largest emitters in the world, to come together in order to do work not just for ourselves, but for all mankind," Kerry told Han.
