The last week saw almost all of the contiguous United States endure above-average temperatures, and more dangerously hot weather is predicted. The European continent experienced wildfires and hundreds, if not thousands, of deaths due to record high temperatures that preceded the US heat wave.
WHAT DO HEAT WAVES DO?
There is no one scientific definition of a heat wave. The number of days over a particular temperature or percentile above the normal can be used to gauge a region’s climate.
ARCTIC WARMING AND JET STREAM MIGRATION
There is a shrinking difference between temperatures in the north and those closer to the equator because the Arctic is warming three to four times faster than the rest of the world.
That is resulting in swings in the North Atlantic jet stream, which in turn leads to extreme weather events like heat waves and floods, according to Jennifer Francis, senior scientist at the Woodwell Climate Research Center.
Heat domes, which trap heat across wide portions of the earth’s surface, are caused by warmer waters. According to the U.S. Weather Prediction Center, the heat dome this weekend is extending from the southern plains of the Oklahoma/Arkansas region all the way to the eastern seaboard.
A significant shift in water temperatures from west to east in the tropical Pacific Ocean during the previous winter, according to scientists, is the primary source of heat domes.
According to the U.S. National Oceanic and Atmospheric Administration, ‘while prevailing winds bring the hot air east, the northern shifts of the jet stream trap the air and move it toward land, where it sinks, resulting in heat waves.’
EL NIÑO AND LA NIÑA
The climate patterns known as El Nio and, less frequently, La Nia occur every few years. On the western coast of North America, El Nio delivers warm water from the equatorial Pacific Ocean, whereas La Nia brings colder water.
La Nia is in effect right now. Climate scientists are worried about what a severe heat wave would look like during the following El Nio, when even hotter summer weather could be anticipated, because summer temperatures tend to be lower during La Nia.
HUMAN-INFLUENCED CLIMATE CHANGE
According to scientists, the United States is suffering some of the effects of global climate change brought on by the combustion of fossil fuels.
‘Climate change is making extreme and unprecedented heat events both more intense and more common, pretty much universally throughout the world,’ said Daniel Swain, climate scientist at UCLA.
‘Heat waves are probably the most underestimated type of potential disaster because they routinely kill a lot of people. And we just don’t hear about it because it doesn’t kill them in, to put it bluntly, sufficiently dramatic ways. There aren’t bodies on the street.’
According to Francis of the Woodwell Center, climate change is causing changes in wind patterns and weather patterns around the planet, which ‘make these heat waves, like the ones we’re experiencing right now, more intense, more persistent, and cover areas that just aren’t used to having heat waves.’
According to NASA’s Goddard Institute for Space Studies researcher Alex Ruane, as the planet heats, ‘We are more easily pushed into the extreme heat categories by natural anomalies. You’re more likely to experience multiple heat waves at once since we’re getting closer to those thresholds. This is happening here in the US.’