How heat waves form

HEAT waves begin when high pressure in the atmosphere moves in and pushes warm air toward the ground.

That air warms up further as it is compressed, and we begin to feel a lot hotter.

The high-pressure system pressing down on the ground expands vertically, forcing other weather systems to change course. It even minimises wind and cloud cover, making the air more stifling. This is also why a heat wave parks itself over an area for several days or longer.

The high-pressure system also pushes out cooler, fast-moving air currents and squeezes clouds away, which gives the sun an unobstructed line of sight to the ground.

The ground — soil, sand, concrete, and asphalt — then bakes in the sunlight, and in the long days and short nights of summer, heat energy quickly accumulates and temperatures rise.

What can you do to stay safe in the heat? Give yourself time to acclimatise

It takes a week or two to get used to extreme heat. Increase the amount of time you spend outdoors each day gradually, if you can, by about 20 percent.

Even a five or 10-degree temperature drop can make a big difference.

Go outside in the morning or evening Know the signs of heat exhaustion and heatstroke

If you have got heat exhaustion, you’ll be sweating profusely, and you may feel a little nauseated. Your skin may be red and hot to the touch, as if you have a fever. If your body approaches heatstroke, which is severe enough to require medical attention, you will stop sweating, and your core temperature will elevate quickly.

Know what to do if you’re suffering from heat-related illness. The top priority is to hydrate. Drink water. You can also use ice packs (in the groin or armpits) and sit near a fan if possible.

How climate change worsens heat waves It can be tricky to tease out how a specific weather event was influenced by climate change, but scientists in recent years have been developing models and experiments to figure out just how much humanity’s hunger for fossil fuels is making individual disasters worse. It’s part of a subfield of climatology known as attribution science, and extreme heat is the classical example.

“Heat waves were actually the extreme events that attribution science were pioneered around,” said Jane W. Baldwin, a postdoctoral fellow at the Lamont-Doherty Earth Observatory at Columbia University.

“Almost any kind of metric related to heat waves you can imagine is getting worse and is projected to get worse.”

Climate change caused by greenhouse gases from burning fossil fuels is poised to make heat waves longer, more intense, and more frequent.

It takes time for the dust to settle on the heat waves of a given moment, to allow scientists to evaluate just how much humans have contributed to the problem.

But researchers looking at past events and other parts of the world have already found that humans share a huge portion of the blame.

After a summer 2019 heat wave was blamed for 2 500 deaths in Western Europe, a study found that climate change made the heat five times as likely as it would have been in a world that hadn’t warmed.

Heat waves in the ocean have become 20 times as likely as average temperatures have risen. And researchers reported that the 2020 heat wave in Siberia was 600 times as likely due to climate change than not.

Impact of heat waves

Air pollution also gets worse as rising temperatures increase the rate of formation of hazards like ozone. Such pollutants in turn exacerbate heart and lung problems. The rise in night time temperatures is particularly worrisome for public health. Without much overnight cooling, people living through a heat wave experience higher cumulative heat stress, increasing risks of problems like dehydration and disrupting sleep, which can further worsen exhaustion and stress from high temperatures.

Alongside the heat, another important factor to consider for human health is humidity. The amount of moisture in the air affects how well sweat can evaporate off the body and cool it off.

Elderly people and very young children face some of the highest risks from extreme heat. People with certain health conditions, like high blood pressure and breathing difficulties, also face greater harm.

But even otherwise healthy people can suffer from heat waves if they are exposed for long durations, such as those working outdoors in agriculture and construction. — www.vox.com