WHAT IS A HEAT DOME?

 

We’re going to see a lot more major heat events – and they’re going to get hotter and longer – as long as the world keeps burning fossil fuels.

3 min read

As you might expect, extreme heat is one of the most direct and easiest to understand effects of the man-made climate crisis.

The science couldn’t be clearer on this one: Burning fossil fuels releases greenhouse gases like carbon dioxide that trap more heat in the atmosphere. More greenhouse gases equals more heat trapped. It’s just that simple.

Extreme heat elevates the rate of death from illnesses like heart attack, heat stroke, organ failure, and more. And sadly, episodes of extreme heat will likely become more frequent and will occur over a larger portion of the planet in the coming decades.

But one particular type of heat-related phenomenon has been getting plenty of headlines recently. It’s called a “heat dome” – and it’s being made worse by climate change.

WHAT IS A HEAT DOME?

A heat dome is a weather phenomenon where hot air is trapped over a certain area, causing extreme heat.

Here's how it works:

• A high-pressure system stalls: A strong area of high pressure in the upper levels of the atmosphere gets stuck over a particular region.
• This traps hot air in place: Warm air gets trapped under the stalled high-pressure system and can’t get out. This “dome” of hot air can't rise up and escape, so it sits over a region.
• Sunshine further intensifies the heat: With little to no clouds because of the high-pressure system being in place, the sun's radiation directly hits the ground, further increasing the temperature within the heat dome.

 

It's like a lid on a pot, trapping the hot air and preventing it from escaping – often for extended periods of time.

Heat domes can cause dangerously high temperatures that linger for days or even weeks, posing significant health risks.

HOW IS IT DIFFERENT FROM A HEAT WAVE?

While both heat waves and heat domes are associated with scorching temperatures, there is a meteorological distinction between the two.

A heat wave is a prolonged period of abnormally warm weather, typically lasting for days or sometimes even weeks. It's defined in relation to a specific location's historical temperature averages. If a particular place experiences above-average heat for a period of time, that place is enduring a heat wave.

Heat waves can occur due to various factors, including trapped warm air similar to that of a heat dome but not exclusively due to that reason. Sometimes a particular place, for a multitude of reasons, just experiences a prolonged period of elevated temperatures and often humidity – and that can constitute a heat wave.

A heat dome, meanwhile, is a specific weather phenomenon. As discussed above, it involves a high-pressure system lingering over a set region and trapping hot air. This can, in some cases, cause more intense and longer-lasting heat compared to regular heat waves.

Some climate scientists believe that changes in the jet stream, brought on by our warming planet, are leading to longer and perhaps more frequent heat domes.

Because of our increasing heat-trapping greenhouse gas emissions, heat waves in general are occurring more frequently and with greater intensity. In the 1960s, in major cities the US, there were an average of two heat waves a year. By the 2010s, that number had increased to six.