Heatwaves have broken records around the world this year, with warnings issued across the United States and temperatures endangering lives across southern Europe.

In June, millions of Americans sweltered as temperatures exceeded 40 degrees Celsius (104 degrees Fahrenheit). In early July, Europe was gripped by a heatwave that meteorologists said was "exceptional" because it struck so early in the year.

Is climate change the main driver of new heat records? In a word, yes. Climate change is fuelling a range of extreme weather around the world, from flooding and storms to droughts, but the change it is most clearly producing is more extreme heat.

A March heatwave in Central Asia was unusually intense, said World Weather Attribution (WWA), a global team of scientists who examine the role played by climate change in extreme weather. Climate change made it about 4 C hotter, it said.

The continued release of planet-heating emissions - largely from the use of coal, oil and gas - will push global temperatures into "uncharted territory" in the coming years, scientists have said.

Heat trapped in the atmosphere by greenhouse gases from burning fossil fuels is raising temperatures to levels unfamiliar to many parts of the world.

About 90% of that excess energy - or heat - has so far been absorbed by the world's oceans, moderating temperature increases.

But ocean surface temperatures are now at their highest level ever recorded, say scientists.

They fear seas may be reaching the limits of their heat-absorbing abilities, which could mean more heat stuck in the atmosphere and temperatures riding even more.

Many people look forward to hot summer temperatures - especially holidaymakers - and photographs on sweltering days still often show people at the beach or splashing in fountains.

But heat can be deadly and many people are unprepared, scientists say. Extreme heat stress has already doubled in the last 40 years, according to the U.S. space agency NASA.

Especially in already humid places, when heat and humidity combine to produce a so-called "wet bulb" temperature above 35 C(95 F), the human body can no longer effectively get rid of enough heat, scientists say.

In such extreme heat conditions people can die without swift access to air conditioning, fans or other ways of cooling.

Around 2,300 people died of heat-related causes across 12 European cities during the severe heatwave between June and July, according to scientists at Imperial College London and the London School of Hygiene and Tropical Medicine.

European health institutes reported that as many as 61,000 people may have died in Europe's heatwaves in 2022.

In 2021, an unprecedented heatwave killed hundreds in the U.S. state of Washington and neighbouring Canada.

Extreme heat could also spur other types of disasters, from water shortages, worsening droughts, wildfires and biodiversity loss.

Heatwaves could also hurt economies as workers find it increasingly difficult to do their jobs, especially those toiling outdoors.

Building awareness that heatwaves are becoming increasingly deadly is a first key step, doctors and scientists say.

Heat researchers have proposed giving heatwaves names, as already happens with hurricanes and other powerful storms, to emphasise the level of threat they present to people.

However, the United Nations' World Meteorological Organization has said this was "not necessarily appropriate for or translatable to heatwaves" since they are not predictable and trackable like tropical cyclones.

Ensuring that those in the path of heatwaves have access to reliable cooling is also crucial, but increases demand for electricity and can spark power outages.

Because growing use of air conditioning can drive more climate change and produce even hotter temperatures, finding low-carbon means of cooling, such as using wind and solar, is crucial, scientists say.

Shifting work and school hours to cooler parts of the day and providing more breaks and water for workers can save lives, scientists say, as can finding simple, low-cost ways to make homes, schools and workplaces cooler, such as by painting roofs white.