As heat waves continue to bake parts of the world, even in September, scientists are reporting that this summer was the hottest on record – and by a significant margin.
June to August was the planet’s warmest such period since records began in 1940, according to data from the European Union’s Copernicus Climate Change Service.
The global average temperature this summer was 16.77 degrees Celsius (62.19 Fahrenheit), according to Copernicus, which is 0.66 degrees Celsius above the 1990 to 2020 average – beating the previous record, set in August 2019, by nearly 0.3 degrees Celsius.
Typically these records, which track the average air temperature across the entire world, are broken by hundredths of a degree.
This is the first set of scientific data to confirm what many had believed was inevitable. It’s been a blisteringly hot summer for swaths of the Northern Hemisphere – including parts of the United States, Europe and Japan – with deadly, record-breaking heat waves and unprecedented ocean temperatures.
August was also the warmest such month on record, according to the new Copernicus data, and warmer than every other month this year except for July. The global average temperature for the month was 16.82 degrees Celsius – 0.31 degrees warmer than the previous record set in 2016.
“The dog days of summer are not just barking, they are biting,” said António Guterres, secretary-general of the United Nations, in a statement about the Copernicus data. “Our planet has just endured a season of simmering – the hottest summer on record. Climate breakdown has begun.”
Both July and August are estimated to have been 1.5 degrees warmer than pre-industrial levels according to Copernicus – a key threshold scientists have long warned the world must stay under to prevent the most catastrophic impacts of climate change.
While scientists are more focused on long-term global temperature rises, these temporary breaches are an important preview of what the world can expect summers to look like at 1.5 degrees of warming.
Countries in the Southern Hemisphere have also experienced startlingly warm winters, with well-above average temperatures recorded in Australia, several South American countries and Antarctica.
In July, a sudden marine heat wave off the coast of Florida saw the ocean reach “hot tub” temperatures. While in June, parts of the North Atlantic experienced a “totally unprecedented” marine heat wave with water temperatures up to 5 degrees Celsius (9 degrees Fahrenheit) hotter than usual.
Every single day from the end of July to the end of August has seen ocean temperatures exceed the previous record set in 2016, according to Copernicus.
Whether this year will end up being the planet’s warmest on record is not yet clear, but it looks certain to come extremely close.
With four months of the year remaining, 2023 currently ranks as the second warmest on record, according to Copernicus, only 0.01 degrees Celsius below 2016, which is currently the warmest year on record.
Scientists say next year is likely to be even hotter, given the arrival of El Niño, a natural climate fluctuation that brings warmer-than-average sea-surface temperatures and influences weather.
“This El Niño is developing in a warmer ocean than any previous El Nino so we are watching with interest how this event develops in terms of strength and impact,” Samantha Burgess, deputy director of Copernicus, told CNN
Burgess said the summer had been one of tumbling records and it would only get worse if the world continues to burn planet-heating fossil fuels.
“The scientific evidence is overwhelming – 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,” she said in a statement.