The life of almost all animals in the ocean depends on the availability of oxygen, which is dissolved as a gas in seawater. However, the ocean has been continuously losing oxygen for several decades. Over the past 50 years, oxygen loss has accumulated globally to about 2% of the total inventory (regionally sometimes much more). The main reason for this is global warming, which leads to a decrease in the solubility of gases and therefore also of oxygen, as well as a slowing down of ocean circulation and vertical mixing. A new study published today in the scientific journal Nature communications shows that this process will continue for centuries, even though all CO2 emissions and therefore warming at the Earth’s surface would be stopped immediately.
“In the study, a model of the Earth system was used to assess what would happen in the ocean in the long term if all CO2 the emissions would be stopped immediately ”, explains the author, Professor Andreas Oschlies of the GEOMAR Helmholtz Center for Ocean Research Kiel. seen so far in the ocean, ”Oschlies continues.
The long-term decrease in oxygen mainly takes place in the deeper layers. According to Professor Oschlies, this also has an impact on marine ecosystems. A so-called “metabolic index”, which measures the maximum possible activity of oxygen-breathing organisms, shows a general decline of up to 25%, especially in deep water (below 2000 meters). This is likely to lead to major changes in this habitat, which was previously considered very stable, explains the oceanographer. These changes have already been initiated by our historic CO2 emissions and are now on their way to the deep ocean. He recommends that a thorough investigation of the deep ocean habitat, which has only been studied at random so far, should take place before this environment, which has been considered stable for many millennia, is likely to change significantly due to the now expected decrease. in oxygen.
In the upper layers of the ocean, the model shows a much faster response to climate action. There, further expansion of minimal oxygen zones relatively close to the surface can be halted within a few years if emissions are stopped. An ambitious climate policy can therefore help prevent at least ecosystems close to the surface from being subjected to additional pressure by a gradual decrease in oxygen.
Source of the story:
Material provided by Helmholtz Center for Ocean Research in Kiel (GEOMAR). Note: Content can be changed for style and length.