Multiple regions around the world are facing another round of record-breaking temperatures as summer heat intensifies, according to a report published by Wired. The sweltering conditions are being driven by abnormally hot ocean waters, El Niño, changes to the jet stream that trap high temperatures in place, and human-caused climate change. The heat wave is painting large swaths of the global weather map red.
Western Europe experienced its hottest June on record and record-breaking wildfires in July, and is now confronting another round of extreme temperatures. French president Emanuel Macron described the combination of severe heat and intense wildfires as "the toughest since the Second World War," with hundreds of heat records falling across Europe from Spain to Germany. In the western US, Phoenix is expected to see temperatures climb to 115 degrees Fahrenheit (46 degrees Celsius) this weekend, while Salt Lake City could hit a record-breaking 106 Fahrenheit. Montana is under an extreme heat watch, with some areas forecast to reach 110 Fahrenheit. The city of Phoenix tied the record for its highest overnight low temperature last Thursday, bottoming out at 97 degrees Fahrenheit. Parts of Asia, including South Korea and Japan, are also dealing with scorching heat.
Climate scientist Daniel Swain of the University of California Agriculture and Natural Resources said that "all of these interior Western cities will be at our near record temperatures for early August," which is already typically a hot time of year. He noted that Phoenix won't see temperatures "drop much below 100 degrees" overnight, calling that "extremely, extremely hot, even for a place that is infamous for being very hot." Senior scientist Jennifer Francis of the Woodwell Climate Research Center explained that the seas around Europe are "running a fever," with these abnormally warm ocean temperatures directly linked to heat-trapping carbon pollution. Francis pointed out that about 90 percent of that trapped heat goes into the ocean, and we're experiencing the consequences this summer. A recent analysis found that the June heat wave in Europe, which left more than 1,000 people dead, would not have been possible without the extra heat from burning fossil fuels.
The report explains that the extreme temperatures are being fueled partly by a series of heat domes, which are areas of high pressure that lock in sunny skies and warmth. These high-pressure systems are remaining stationary because of the shape of the jet stream, the band of air that flows from west to east around the northern hemisphere and creates most of the weather patterns we experience. When the jet stream becomes wavy, it can allow tropical air to push northward and become trapped over regions that are normally more temperate. In Europe's case, the jet stream is pulling extra heat from the unusually warm ocean waters surrounding the continent. The oceans around Japan and China are also running warmer than normal, helping to drive heat waves in those areas. Regional weather patterns are also contributing—the western US heat wave is being influenced in part by downwind effects from Hurricane Genevieve, a Category 5 hurricane that formed over warm ocean waters off Mexico's coast this week.
The hot and dry conditions have the potential to intensify some of the fires already burning across Montana and other western states. The combination of record-breaking daytime highs and unusually warm overnight temperatures creates dangerous conditions, particularly in cities where temperatures fail to drop enough to provide relief. With the jet stream locked in its current wavy pattern and ocean temperatures remaining abnormally high, these heat waves represent a direct consequence of decades of carbon pollution accumulating in the atmosphere.