Mediterranean Sea Getting Saltier, Hotter
The Western Mediterranean Sea is heating up and getting saltier, a new study finds.
Each year the temperature of the deep layer of the Western Mediterranean increases by 0.0036 degrees Fahrenheit (0.002 degrees Celsius), and its salt levels increase by 0.001 units of salinity, researchers monitoring the sea found. The change is consistent with the expected effects of global warming.
These changes may sound like small beans, but they have been building up at a faster pace since the 1990s, the study, detailed in the April 1 edition of the Journal of Geophysical Research, suggests.
The results show a consistent trend, "but to confirm this accelerating trend, we need to monitor it over the years to come," said study author Manuel Vargas-Yáñez of the Spanish Institute of Oceanography.
The researchers analyzed the temperature and salt levels of the three layers of the Mediterranean Sea: the upper layer (from the surface to 656 feet, or 200 meters, deep with water that enters from the Atlantic); the middle layer (from 656 to 1,968 feet, or 200 to 600 meters, deep with water from the eastern Mediterranean that enters the western basin via the Strait of Sicily); and the deep layer (from 1,968 to the sea bed, or 600 meters and deeper, with water from the western Mediterranean).
"These layers, especially the deep one, take up a huge volume, and raising its temperature each year by one-thousandth of a degree requires an enormous amount of heat," Vargas-Yáñez said.
The team has also observed an increase in the salt level and the temperature of the middle layer of the sea. This has not been clearly observed in the upper layer, "but it can be deduced from the heating of the deep water and from studies done by other teams and our current research projects," Vargas-Yáñez said.
An increase in ocean salinity suggests an increase in the net evaporation of the water — the difference between evaporation and precipitation. When evaporated water leaving the ocean is greater than water entering the ocean as precipitation that means overall less water staying in the sea with the same amount of salt. So the sea gets saltier.