Climate change is making seas saltier, the effect is no joke

Jakarta –

Major changes in the circulation of the ocean have caused the waters of the North Atlantic Ocean to be much saltier in the last 50 years compared to the other great ocean in the world, the Pacific Ocean.

Evaporation is more intense in the Atlantic Ocean compared to the Pacific Ocean, especially in tropical and subtropical areas, increasing its salinity by absorbing its water content. In addition, the Pacific Ocean is connected to larger river systems, allowing it to be constantly refreshed with more water from the mountains and inland rivers.

In a new study, scientists found that changes in the world’s climate and weather systems are beginning to increase these effects, increasing the salinity differences between the two oceans.

Researchers from the Chinese Academy of Sciences found that the Atlantic-Pacific salinity contrast has increased by almost 6% between 1965 and 2018, an effect that is particularly visible in the upper 800 meters of water in the northern mid-latitudes. .

The two main reasons for this movement are warming and wind. An increase in ocean temperatures has caused the thermocline (a series of oceans defined by rapid temperature changes) to move poleward. Meanwhile, changing winds have pushed water up in the mid-latitude oceans.

Both of these effects have also been seen in the Pacific Ocean, but are more prominent in the Atlantic Ocean, where they cause large changes in salinity.

However, the researchers note that they do not fully understand the mechanisms behind this complex relationship. When they used ocean models driven by real world atmospheric data, the models struggled to accurately reproduce conditions observed in certain regions, leading to uncertainty in the mechanistic understanding.

Nevertheless, the findings appear to point to another, unexpected way in which human-induced climate change is reshaping the Earth’s fundamental systems.

Changes in salinity levels can also trigger chain effects that affect many aspects of the marine environment. First, the researchers wondered whether changes in the salinity of the Atlantic Ocean could destabilize its different layers, which are formed from water of different densities and temperatures.

In turn, this can push anthropogenic heat deeper into the ocean, where it persists as a true ‘hot spot’.

For another example, increased salt levels in the ocean can make it difficult for oxygen and nutrients to move between the surface and deeper waters, reducing its ability to support plant and algae growth. Since these life forms support a large part of the ocean’s food chain, their effects can be enormous.

(rns/fay)