In the latest issue of journal Nature the oceanographers published the most comprehensive study on global oxygen content in the world’s oceans.
Main findings of Study:
The ongoing global change causes rising ocean temperatures and changes the ocean circulation. Therefore less oxygen is dissolved in surface waters and less oxygen is transported into the deep sea. This reduction of oceanic oxygen supply has major consequences for the organisms in the ocean.
Study demonstrates that the ocean’s oxygen content has decreased by more than two percent over the last 50 years.
The study shows that, with the exception of a few regions, the oxygen content decreased throughout the entire ocean during the period investigated. The greatest loss was found in the North Pacific.
While the slight decrease of oxygen in the atmosphere is currently considered non-critical, the oxygen losses in the ocean can have far-reaching consequences because of the uneven distribution. For fisheries and coastal economies this process may have detrimental consequences.
The results of the research are consistent with most model calculations that predict a further decrease in oxygen in the oceans due to higher atmospheric carbon dioxide concentrations and consequently higher global temperatures.
The new study is an important result for the ongoing work in the Collaborative Research Center (SFB) 754 funded by the German Research Foundation (DFG) at the Kiel University and GEOMAR. The SFB 754’s aim is to better understand the interaction between climate and biogeochemistry of the tropical ocean.
Background:
Oxygen is an essential necessity of life on land. The same applies for almost all organisms in the ocean. However, the oxygen supply in the oceans is threatened by global warming in two ways: Warmer surface waters take up less oxygen than colder waters.
In addition, warmer water stabilizes the stratification of the ocean. This weakens the circulation connecting the surface with the deep ocean and less oxygen is transported into the deep sea.
Therefore, many models predict a decrease in global oceanic oxygen inventory of the oceans due to global warming. The first global evaluation of millions of oxygen measurements seems to confirm this trend and points to first impacts of global change.