According to the United Nations Climate Action, as the ocean warms from the excess heat and energy, there are unmatched cascading effects, resulting in ice melting, sea level rise, marine heat waves, and ocean acidification.
More concerning climate change indicators include the oceans' inability to absorb heat generated by rising greenhouse gas emissions trapped in the Earth's system. This is becoming more noticeable in the Mediterranean Sea, where reports indicate that a process known as stratification, more than ever, is interfering with the way the sea processes carbon dioxide.
Rising Temperatures Triggers Shift in Mediterranean Hydrodynamics
The separation of water into layers based on a specific quantity is known as stratification. According to a 2020 Nature journal article, layered stratification occurs in all ocean basins. The stratified layers act as a barrier to water mixing, affecting the exchange of heat, carbon, oxygen, and other nutrients.
Three layers of water masses are observed in the Mediterranean: a surface layer, an intermediate layer, and a deep layer that sinks to the bottom. This type of ocean structure allows the Mediterranean to break down the carbon dioxide stored there, taking care of most of the planet's emissions.
As per UN Climate Change, the ocean has absorbed approximately 90% of the heat generated by rising emissions. However, as the eastern Mediterranean Sea warms in the summer, it can no longer absorb that gas and begins to release it. Or Bialik, a geoscientist studying the phenomenon, explained that rising temperatures decrease the sea's ability to hold CO2.
Carbonate Crystals Appearing?
As reported by Wired, the fluid on top of the Mediterranean does not mix much with the underlying colder layers in the hot, shallow, stable waters, as opposed to deeper parts of the ocean, where upwelling brings up cooler H2O.
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"The conditions are so extreme that we can definitely generate calcium carbonate chemically from these waters," Bialik explains. As stratification increases, the density differences between ocean layers also increase, resulting in larger mixing barriers.
As per Bialik's research, the said continuous stratification causes the formation of carbonate crystals, which emit CO2. So much so, according to Bialik, they account for roughly 15% of the gas emitted into the atmosphere by the Mediterranean Sea. Furthermore, modeled predictions of sea surface temperature indicate that this process may weaken in the future, resulting in increased alkalinity and atmospheric CO2 buffering capacity.
According to Encyclopedia Britannica, increasing industrialization, shoreline human settlements, and tourism have led to heavily contaminated waters throughout many Mediterranean coastal areas. Because of the region's weak tidal and current movements, pollution tends to remain close to its source in the Mediterranean.
Bialik adds, "They [crystals] could probably form around any nucleation center." The scientist also thinks that microplastics might also be a factor in forming carbonate crystals.
