For more than three months, sea surface temperatures in the North Atlantic have been higher than those recorded during this time of year. This may be related to the combined effects of climate change, the development of El Niño conditions, and a lack of Saharan dust.
Temperatures in the North Atlantic tend to rise in summer, peaking in late August or early September. On March 5, the average temperature reached 19.9 °C, exceeding the previous record set in 2020 by 0.1 °C, according to data presented by researchers at the University of Maine, dating back to 1981.
On June 11, they reached a maximum of 22.7 °C, 0.5 °C above the previous maximum set in 2010.
“It’s clearly out of the envelope,” he says. Francois Lapointe at the University of Massachusetts Amherst. “That is very concerning.”
The unusual Atlantic temperatures are part of a pattern of above-average surface temperatures across the world’s oceans, which reached an all-time high of 21.1°C on April 1. Average sea surface temperatures have dropped to 20.9°C since then, but still remain 0.2°C above the previous maximum set in 2022.
It’s unclear what is driving the unusual heat in the North Atlantic, but the anomaly has sparked speculation among researchers. Climate change has likely contributed to some extent, Lapointe says. The natural variability of warmer El Niño conditions emerging in the tropical Pacific Ocean may also have contributed.
Another possible factor proposed by miguel mann at the University of Pennsylvania is that there is less dust from the Sahara desert over the ocean than usual.
One anomaly that has received a lot of attention is the North Atlantic, where we see heat particularly in the eastern tropical/subtropical region of the basin. That appears to be related to an anomalous paucity of windblown Saharan dust that normally has a cooling impact on the region.
— Professor Michael E. Mann (@MichaelEMann) June 12, 2023
Dust clouds carried by the ocean from the Sahara generally have a cooling effect in the North Atlantic during this part of the year, reflecting solar radiation that heats the water. But the dust-blowing trade winds are weaker than normal, and only slight amounts of dust are scheduled for the end of June. Lapointe says that weaker trade winds are associated with El Niño.
The lack of dust is unlikely to have anything to do with climate change, Mann said on Twitter. “Instead, it underscores the interplay between human-caused warming and natural variability.”
Higher sea surface temperatures could generate more powerful storms, though changes in wind patterns due to El Niño could offset those effects. If sustained, they could also harm marine ecosystems by reducing mixing between the different layers of the ocean, which decreases available oxygen, Lapointe says.