Jul 6, 2023 - Energy & Environment

Earth sees three hottest days on record

Daily global mean surface air temperatures
Data: NOAA CFS/CFSR via Climate Reanalyzer, University of Maine; Chart: Simran Parwani/Axios

The past three days have each broken or tied records as the Earth's hottest day since at least 1979 and likely far longer, according to National Oceanic and Atmospheric Administration data, accessible via a University of Maine website.

Why it matters: Daily temperature milestones are largely symbolic — but point to an alarming trend, scientists say.

Zoom in: The accessibility of global climate data is fueling interest in — and concern over — signs that the planet is warming faster than anticipated. That is tied in part to El Niño conditions in the tropical Pacific, as well as human-caused emissions of greenhouse gases.

The big picture: The daily heat records on July 3, 4 and 5 are novel in part because the last time the world saw such a dramatic spike in global average temperatures was in August 2016. That date featured the last strong El Niño event, Gavin Schmidt, director of NASA's Goddard Institute for Space Studies in New York City, tells Axios via email.

  • At that time, computer model "reanalysis" data from NOAA's National Centers for Environmental Prediction was not being piped directly online in such an easily accessible way, he said.
  • Instead, that year "the attention was directed towards the monthly means," which are released on a slight time delay from NOAA, NASA and other agencies, Schmidt explains.
  • "The novelty of the metric is part of what’s driving this," he said, regarding the media and public attention on the daily mean temperature.

Between the lines: The record daily high temperatures come from a computer model that takes in readings from thermometers on the land and aboard ocean buoys, plus data from satellite sensors and weather balloons to arrive at a best-estimate of the global average temperature for the planet during one-hour increments of each day.

  • "It's not a surprise at all and it will be broken again soon," Friederike Otto, a senior lecturer in climate science at Imperial College London, said of the daily records.
  • "This record is the visible part of a huge amount of silent and often unnoticed suffering and dying of people and ecosystems," she tells Axios via email.
  • "We live in a dramatically different world to just a few years ago," Otto said. She advocated taking steps to reduce society's vulnerability to climate change, along with stopping the use of fossil fuels.

What they're saying: Kate Marvel, a senior climate scientist at Project Drawdown, a nonprofit focused on climate solutions, said the record temperatures are not surprising given emissions and climate trends.

  • "Atmospheric CO2 levels have increased nearly 50%. Methane levels have increased by more than 150%. If an athlete was using banned substances to this extent, no one would be surprised if he started to break records," she said.
  • "We would also probably be worried about his health and would strongly urge him to stop doing that before it’s too late."
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