Summer 2023 was hottest on record globally, New figures show

Europe's Earth observation agency Copernicus states that extreme heat waves impacted North America, Europe, and Asia, making this summer

By Ground report 06 Sep 2023

New Update

Summer 2023 was hottest on record globally, New figures show

Europe's Earth observation agency Copernicus states that extreme heat waves impacted North America, Europe, and Asia, making this summer the warmest on record globally by a large margin.

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

The monthly climate monitoring reports from the European Union’s Copernicus Climate Change Service, the US National Oceanic and Atmospheric Administration and NASA confirm the extraordinary pace of climate change as a result of heat-trapping greenhouse gases in the atmosphere.

publive-image — Ranking 30 warmest boreal summers in ERA5 data. Data: ERA5. Credit: C3S/ECMWF.

August was warmer than pre-industrial averages by about 1.5 degrees Celsius (2.7 degrees Fahrenheit), which is the warming threshold that the world is trying not to pass. However, scientists do not consider that brief passage significant as the 1.5 C threshold should be observed over decades, not just one month.

According to the WMO and Copernicus, the world's oceans, which make up more than 70% of the Earth's surface, recorded the hottest temperatures ever, reaching nearly 21 degrees Celsius (69.8 degrees Fahrenheit), and they have set high temperature records for three consecutive months.

"In a statement, United Nations Secretary-General Antonio Guterres said, 'The dog days of summer are not just barking, they are biting. Climate breakdown has begun.'"

Record-Breaking Heat and Sea Surface Temperatures

The global-mean surface air temperature for August 2023 reached a scorching 16.82°C, a staggering 0.71°C above the August average for the period of 1991-2020. Moreover, this figure surpassed the previous record-holder, August 2016, by 0.31°C. Disturbingly, August 2023 was approximately 1.5°C warmer than the preindustrial average for 1850-1900.

The Northern Hemisphere bore the brunt of heatwaves during JJA 2023, with regions such as southern Europe, the southern United States, and Japan experiencing abnormally high temperatures. Notably, Australia, several South American countries, and parts of Antarctica also faced well-above-average temperatures.

Marine air temperatures followed suit, with several regions reporting well above-average sea surface temperatures. In a startling trend, global sea surface temperatures consistently exceeded previous records from April 2023, making August 2023 the month with the highest global monthly average sea surface temperatures ever recorded—registering at 20.98°C, a 0.55°C anomaly.

Marine Heatwaves and El Niño Conditions

The North Atlantic shattered previous records as well, with temperatures surpassing the previous daily high of 24.81°C set in September 2022. The region continued to experience elevated sea surface temperatures throughout August, reaching a new pinnacle of 25.19°C on August 31.

Marine heatwave conditions formed in the North Atlantic, particularly west of the Iberian Peninsula, while subsiding in most of the Mediterranean. Furthermore, El Niño conditions continued to develop in the equatorial eastern Pacific.

In the polar regions, Antarctic sea ice extent plummeted to a record low for August, registering 12% below average. Conversely, Arctic sea ice extent remained below average, although it exceeded the record minimum observed in August 2012.

August 2023 witnessed a stark contrast in precipitation patterns. Central Europe and Scandinavia experienced above-average rainfall, leading to flooding, while regions spanning the Iberian Peninsula, southern France, Iceland, Eastern Europe, and the southern Balkans faced drier-than-average conditions. Notably, wildfires ravaged parts of France, Greece, Italy, and Portugal.

In North America, wetter-than-average conditions prevailed in the northeast and western regions, triggering floods due to Hurricane Hilary. Meanwhile, regions in the southern USA and northern Mexico, as well as across Asia and South America, grappled with drier-than-average conditions.