It has never been so hot in the world's oceans (at least not since data have been collected) as it was in the last few days until March 18. MeteoNews takes stock of this unprecedented phenomenon.
A temperature peak in March
In general, the global average ocean temperature peaks at this time of year. The summer in full swing in the Southern Hemisphere until February contributes to this trend: the heat stored during the summer season takes some time to be reflected on the thermometer.
This time, the situation takes an unusual turn. The average global water temperature has passed the 21 degree mark - a record high. This data takes into account all the world's oceans.
Fig. 1; Source: NOAA - Maine University
An unprecedented measurement
This is the first time such a mark has been observed since data collection began in 1981.
It is also worth mentioning that La Niña has just bowed out after almost three years of reign. It is not impossible that El Niño will make a remarkable return in the Pacific Ocean, which would have an influence on the global average surface water temperature.
As a reminder, La Niña is a zone of cooling of surface water temperatures off Chile, in the Pacific Ocean. Conversely, El Niño refers to a warm anomaly in the same area.
The Atlantic basin under an abnormal heat
The Atlantic Ocean is no exception. On the contrary, the North Atlantic contributes to this temperature anomaly. This is highlighted by data collected by NOAA and analyzed by the University of Maine's Climate Change Institute.
Fig. 2; Source: NOAA - Maine University
As evidence of this trend, a system with tropical characteristics even formed in the Atlantic in the middle of January - highly unusual.
The north of this vast body of water reached a mark never before seen for an early spring. According to the Maine Climate Office, the thermometer climbed to 6.2 degrees on March 15 in the Gulf of Maine - unheard of. In any case, the first few months of 2023 are among the warmest on record.
Possible impacts
Such anomalies can have a marked influence on the weather. It takes a lot of energy to warm a body of water, but once that heat is present, it is stored relatively permanently. Near this energy reservoir, temperature extremes are less pronounced, and temperatures remain more stable.
However, all of this stored heat could seek to diffuse into the atmosphere. This could eventually contribute to above normal temperatures.
In addition, a sharp contrast between water and land encourages convection, which increases the amount of energy available to the systems. This addition of moisture may therefore increase the explosive nature of some disturbances or thunderstorms in the weeks and months to come.
In summer and autumn, this phenomenon can also feed tropical systems and promote their intensification. Particularly warm water can thus generate more depressions and contribute to more powerful hurricanes. In addition, it can fuel extreme events on land: Tornado Alley in the central United States could experience a particularly active 2023 season, particularly because of the unusually warm waters of the Gulf of Mexico. To be continued...
