London saw high temperatures on June 9, 2023
Guy Corbishley/Alamy
Rising temperatures in the world’s oceans and the arrival of El Niño weather events in the Pacific mean 2023 will be the hottest year on record, and researchers say the planet is entering “uncharted territory”.
The previous warmest year on record was 2016, when the world was also last in a warming El Niño weather pattern (although some agencies say 2020 also took the top spot). Now this month’s temperature records suggest 2023 could be close to 2016. The first 11 days of June recorded the highest global temperatures ever recorded for this time of year, according to Copernicus, the European Union’s Earth observation programme, following the second-warmest May on record and the fourth-warmest April.
The peak occurred on June 9, when the average global air temperature was 16.7 °C (62 °F), just 0.1 °C lower than the warmest on record on August 13, 2016.
It is important to note that while human-induced climate change continues to raise global temperatures, there is no evidence that the process is accelerating this year. Instead, specific warming conditions are stacked on top of the 1.3°C temperature increase caused so far by climate change, pushing records higher and higher.
One of the main causes of the recent extraordinary heat wave is the heat in and above the oceans. For months, scientists have been warning that sea surface temperatures have reached record highs, caused by a series of marine heat waves around the world. In the North Atlantic, temperatures hit a high of 22.7°C on June 11, 0.5°C above the previous June high in 2010.
This is what the surface temperatures of the sea look like right now.
🟥 = Warmer than average
🟦 = Cooler than averageRecords are broken every day. pic.twitter.com/BH9iCXUgXC
— Scott Duncan (@ScottDuncanWX) June 15, 2023
It is not yet clear why the oceans are so hot right now, especially given El Niño conditions, which are bringing warmer sea temperatures, have only just arrived and will not peak until the end of the year,
Weaker trade winds caused by changes in atmospheric dynamics may be the most likely explanation, he says Samantha Burgess at Copernicus. In the North Atlantic, the wind force is decreasing may have reduced the amount of dust that blows through this part of the ocean from the Saharasubstance that usually has a cooling effect on ocean temperatures.
The rise in ocean and air temperatures is “surprising” for the time of year, Burgess says. Globally the first days of June broke through a temperature rise of 1.5°C compared to the same time of year in pre-industrial times — a threshold previously only crossed during Northern Hemisphere winters, when temperature anomalies are more common.
“What we’ve observed so far suggests that 2023 is likely to be in the top five warmest years,” says Burgess. “I think it’s fair to say we’re in unfamiliar territory. No one in human history has ever seen such high ocean temperatures, and the air temperatures we are seeing now are near record-breaking.”
While the major drivers of warming – El Niño conditions plus climate change – are the same as in 2016, the heat manifests itself very differently this year. While the temperature peaks in 2016 were concentrated above the Siberian Arctic, the heat in 2023 was observed in several places, including in the Southern Ocean and Antarctica earlier this year.
In recent months there has been increasing concern about the lack of sea ice in Antarctica, with February 2023 setting a new record for minimum sea ice of just 1.79 million square kilometers. Sea ice is now reforming as the continent enters winter, but it still remains well below average.
Absolute size of the #Antarctica sea ice anomaly is nearly one of the largest on record. Especially striking for this time of year. While the sea ice is growing (Australian winter), it is moving much slower than usual.
Find the seasonal cycle here: https://t.co/V0Lt0w20IQ pic.twitter.com/MqTH9B3eZA
— Zack Labe (@ZLabe) June 15, 2023
“I think the general parallel is that we have this atmospheric variability, especially with El Niño, on top of the general warming trend background. That’s the same as seven years ago,” says Christopher Koopman at the University of Reading, UK. “There is a good chance that we will have another record year this year or next year.”
As El Niño builds over the coming months, scientists expect to see more temperature anomalies as the warming impact begins to tilt weather patterns around the world. “In addition, the world as a whole is slightly warmer, you tend to get regional weather patterns, so you get climate anomalies,” says Manoj Joshi at the University of East Anglia, also in the UK.
But the exact way the heat manifests itself won’t be the same as it was in 2016, Merchant says. “I think it’s unlikely there are parallels in the exact patterns of warm ocean temperatures or land temperatures because the climate doesn’t really repeat like that.”
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