Right now, the world’s most intense heat event is occurring at sea rather than on land.
Water temperatures in the Mediterranean have reached previously unheard-of levels for the early summer due to a protracted, record-breaking marine heat wave. The long-term average for this time of year in the Mediterranean is 23 degrees Celsius (73.4 degrees Fahrenheit), while the current average is 26 degrees Celsius (78.8 degrees Fahrenheit).
The Mediterranean is a vivid, fiery red on a gradient map that displays anomalies in water temperature.
Temperatures are more than 7 degrees Celsius (12.6 degrees Fahrenheit) higher than typical in some areas of the sea, especially in the western basin including Spain, France, and Italy.
U.S. meteorologist Jeff Berardelli stated on social media that it’s absurd for big bodies of water.
The event may not seem as evident to most people as the severe heat wave that is currently affecting the area on land. The Eiffel Tower had to close its summit this week due to the extreme heat dome that engulfed Europe. However, high sea temperatures can have far-reaching and hazardous effects.
In coastal regions, they have the potential to increase humidity and heat. They have the potential to increase atmospheric moisture, which would intensify storms. Additionally, they have the power to upset ecosystems by bleaching coral and causing mass mortality events for species like sponges and sea grasses that are unable to migrate to colder waters.
Karina von Schuckmann, a senior adviser on ocean science for policy at Mercator Ocean International, described this specific incident as extremely worrisome. Because it absorbs the majority of the surplus energy produced by greenhouse gas emissions, she referred to the ocean as the sentinel for planetary warming.
The Mediterranean as a hotspot
As the climate warms, the frequency and severity of marine heat waves—which are characterized by extended, wide-spreading regions of significantly above-normal water temperatures—are rising.
Heat waves are more common in the Mediterranean, which is semi-enclosed and one of the fastest-warming regions in the globe. The Mediterranean has been identified as a hotspot for global climate hazards by the U.N. Intergovernmental Panel on Climate Change (IPCC). Mediterranean marine heat waves have increased in frequency, duration, and intensity, particularly in the past ten years, according to a 2023 study.
Around August 18, the Mediterranean usually reaches its warmest point, with an average temperature of 26.1 Celsius (79 Fahrenheit). On August 13 of last year, it reached its highest temperature ever, 28.5 (83 degrees Fahrenheit). However, in early July of last year, the Mediterranean was 2 degrees Celsius (3.6 Fahrenheit) colder than it is now, at 24 Celsius (75.2 Fahrenheit).
Satellite estimations indicate that the water temperature offshore of Venice and Sanremo, Italy, was approximately 30 degrees Celsius (86 degrees Fahrenheit) this week, while a buoy near the Spanish island of Mallorca recorded a temperature of 31 degrees Celsius (87.8 degrees Fahrenheit).
Ocean regions between Spain and Sardegna are currently experiencing one of the world’s most powerful maritime heat waves, with a severity rating of Level 3 out of 5. In the Gulf of Lion, south of France, and the Alboran Sea, south of Spain, the heat wave has just reached extreme (Level 4 out of 5) levels.
What drives heat in the oceans
A number of oceanic and atmospheric factors must come together for a marine heat wave to develop and get stronger.
Southern Europe and the Mediterranean Sea have been anchored by a strong high-pressure system that spans the lower and middle atmosphere throughout June.
Air sinks, compresses, and warms in high-pressure systems. The amount of heat that this specific dome of high pressure could generate was further increased by drawing very warm air from North Africa into Europe.
Light winds and an abundance of sunshine beneath the system prevented colder, subterranean saltwater from churning to the surface.
The potential severity and duration of maritime heat waves are increasing due to the planet’s and its seas’ long-term warming, which will also cause 2024 to be a record-breaking year worldwide.
The Mediterranean, which had consecutive years of record-breaking ocean warmth in 2023 and 2024, is likely experiencing a heat wave that is being exacerbated by the combination of natural and human-influenced variables.
For this marine heat wave to subside, there must be a major shift in weather patterns, including cooler air temperatures and stronger winds. The Mediterranean heat is expected to persist for a few more weeks, with another severe heat wave perhaps occurring in mid-July.
