Earth sizzled in July and became the hottest month in 142 years of recordkeeping.
As extreme heat waves struck parts of the US and Europe, the globe averaged 62.07 degrees (16.73 degrees Celsius) last month, beating out the previous record set in July 2016 and tied again in 2019 and 2020. The margin was just 0.02 degrees (0.01 Celsius).
The US National Oceanic and Atmospheric Administration (NOAA) said this Friday.
The last seven Julys, from 2015 to 2021, have been the hottest seven Julys on record, said NOAA climatologist Ahira Sanchez-Lugo. Last month was 1.67 degrees (0.93 degrees Celsius) warmer than the 20th century average for the month.
"In this case, first place is the worst place to be," NOAA Administrator Rick Spinrad said. "This new record adds to the disturbing and disruptive path that climate change has set for the globe."
Warming on land in western North America and parts of Europe and Asia drove the record-setting heat, Ahira said. "While the worldwide temperature was barely higher than the record, what shattered it was land temperature over the Northern Hemisphere."
Northern Hemisphere temperatures were a third of a degree (0.19 degrees Celsius) higher than the previous record set in July 2012, which for temperature records is "a wide margin," she said.
July is the hottest month of the year for the globe, so this is also the hottest month on record.
One factor helping the world bake this summer is a natural weather cycle called the Arctic Oscillation, sort of a cousin to El Nino, which in its positive phase is associated with more warming, the NOAA climatologist said.
Even with a scorching July and a nasty June, this year so far is only the sixth warmest on record. That is mostly because 2021 started cooler than recent years due to a La Nina cooling of the central Pacific that often reduces the global temperature average, Ahira said.
"One month by itself does not say much, but that this was a La Nina year and we still had the warmest temperatures on record ... fits with the pattern of what we have been seeing for most of the last decade now," the University of Illinois meteorology professor Donald Wuebbles said.
The last time the globe had a July cooler than the 20th century average was in 1976, which was also the last year the globe was cooler than normal.
"So if you are younger than 45 you have not seen a year (or July) where the mean temperature of the planet was cooler than the 20th-century average," Princeton University climate scientist Gabriel Vecchi said.