Aug 25, 2023 - Energy & Environment

Simultaneous record heat hits multiple continents

Picture of flames burning from wildfires in Greece amid extreme heat in Aug.

A burning tree during a wildfire near the village of Dikella on Aug. 23 in Greece. Photo: Athanasios Gioumpasis/Getty Images.

A simultaneous spate of extreme heat events have broken longstanding, all-time records on multiple continents this week.

Why it matters: Extreme heat events are the clearest manifestation of climate change in weather that people and the ecosystem experience on a daily basis.

  • Extreme heat can be deadly, causing the most deaths of any weather-related phenomenon in the U.S. during a typical year, according to the National Weather Service.
  • Prolonged heat events with sweltering days and little to no relief at night can be particularly hazardous.

Zoom in: The records from the past week are particularly unusual considering these events are occurring in late August, which is past the typically hottest time of year.

  • It is in keeping with the theme of what is likely to be the Northern Hemisphere's hottest summer on record, with the hottest global average sea surface temperatures in recorded history.
  • Multiple U.S. states during the past week have seen heat indices, a metric that combines heat and humidity to capture how hot it feels to the human body, climb above 115°F, and in some spots, even exceed 125°F.
  • In Chicago on Thursday, the heat index rose to an all-time peak of 120°F, as the air temperature hit 100°F for the first time since 2012.

Context: Extreme heat events globally are becoming more frequent, intense and longer-lasting due to the burning of fossil fuels for energy, deforestation and other contributors to climate change.

By the numbers: For the continental U.S., each day during the past seven has seen about 100 or more hot temperature records set or tied. Those include daytime highs and overnight minimum temperatures.

  • The ratio of hot temperature records to cold records has been about seven-to-one during that time period.
  • New Orleans, for example, tied its all-time high-temperature record of 102°F on Wednesday, while other locations in Louisiana established new benchmarks.

Between the lines: Beyond the U.S., monthly and all-time records have been set this week in France, Spain, Switzerland, Bolivia and Japan, among other nations.

  • In Japan, Sapporo saw its highest temperature on record at 97.3°F (36.3°C). On Twitter, meteorologist Sayaka Mori said that several schools in Hokkaido were closed due to heat for the first time.
  • The region is famous for its winter skiing and hosted the 1972 Winter Olympics.

Of note: Like the U.S., parts of Japan have been experiencing a heat wave that has flared off and on for much of the summer.

  • Some of the most anomalous heat has struck South America during its winter season.
  • This week, for example, Villamontes, in southeastern Bolivia, tied for the warmest winter temperature on record in the Southern Hemisphere, with a high of 113°F (45°C).

The intrigue: None of these heat waves on their own is surprising, particularly during a summer featuring such unusual ocean temperatures, and with a burgeoning El Niño in the tropical Pacific. Both conditions can supercharge global heat extremes.

  • However, to see them occur at the same time is unusual, particularly since even countries supposedly in the grips of their winter season are involved.

Jacob Knutson contributed reporting.

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