Summer 2023 Was the Hottest on Record Globally, New Figures Show

Marine and atmospheric heat waves battered most of the Northern Hemisphere, unleashing fires and deadly storms.

(Bloomberg) — This summer was the warmest on record globally by a large margin as extreme heat waves impacted North America, Europe and Asia, according to Europe’s Earth observation agency Copernicus. 

Temperatures in June, July and August were 0.66 degrees Celsius above the average between 1991 and 2020, Copernicus said. The month of August alone was the warmest on record globally and the second-warmest month ever — only after July 2023. 

“The scientific evidence is overwhelming,” said Samantha Burgess, deputy director of the Copernicus Climate Change Service. “We will continue to see more climate records and more intense and frequent extreme weather events impacting society and ecosystems, until we stop emitting greenhouse gases.” 

Human emissions of greenhouse gases have warmed the planet by about 1.1C since pre-industrial times. Intense heat and sudden rains have resulted in tens of thousands of deaths and billions in losses on every continent. Efforts to reduce humanity’s carbon footprint are still not enough to slow the pace of climate change, with global emissions hitting a record in 2022. 

August was around 1.5C warmer than the average between 1850 and 1900, Copernicus said. That means global temperatures briefly reached the threshold of warming countries agreed to aim for at the end of the century when they signed the Paris Agreement in 2015.

This year is on track to be one of the warmest on record, with the first eight months of the year ranking second-warmest on record, only 0.01C below 2016, the current hottest year on record. 

That heat in the atmosphere over the summer was worsened by a long period of unusually high temperatures that started in April. August beat sea heat records for all previous months since recordings started in the 1970s, with temperatures 0.55C above the historic average for the month. Most unusual were temperatures in the North Atlantic, which breached a new record of 25.19C on Aug. 31.

Antarctic sea ice remained at a record low and 12% below the historic average for the month, Copernicus reported. Concentrations of sea ice in the Arctic was 10% below the average, but above the historic minimum reached in August 2012.

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