May 05, 2017 03:58 PM EDT
Analysis of a historic dataset unveils that oxygen levels in the ocean waters have dropped drastically. The key reason behind this grim condition is the increasing ocean temperature.
A group of researchers at the Georgia Institute of Technology studied an important historic dataset that contains ocean information for more than 50 years. The aim of the study is to know the specific pattern and trends of the dissolved oxygen levels in the ocean water. The researchers revealed that the levels began dropping with the increment of the ocean temperature from the 1980s, Phys.org reported.
Climate variability can be a key cause of the changing concentration of the dynamic properties, exist in the oxygen in the oceans, Taka Ito stated. Taka Ito is the associate professor in Georgia Tech's School of Earth and Atmospheric Sciences and the key personality to lead the research. Interestingly, the outcome of the study shows the actual rate of oxygen loss globally is more than the visible level of random variability of nature. That means the oxygen level is decreasing globally.
The existing marine organisms are already affected by the oceans' decreasing oxygen levels. Frequent occurring of the "hypoxic events" ultimately killed or sometimes displaced the populations of crabs, fish, and other important organisms. Previous research studies anticipated that water temperature would only decrease a percentage of oxygen because warmer water contains less dissolved gas than the colder water. The current study, published in the Geophysical Research Letters, reported the key fact.
Shockingly, the outcome of the research revealed that the oxygen levels in the oceans are decreasing more rapidly than the increasing rate of water temperature. This decreasing trend is two to three times faster than the earlier predictions. Ocean circulation, rapid melting of the polar ice, and increasing the temperature of the near-surface waters are the key reasons behind the crucial change.
The surface level of the ocean mainly absorbs the oxygen from the atmosphere or sometimes created by the photosynthesizing phytoplankton. Now the subsurface water is mixed with the oxygenated water by the ocean currents. But the increasing ocean temperature makes it difficult for the warmer surface water to mix with the downward cooler subsurface waters. This process hampers the oxygen level in the ocean.
On the other hand, the ocean surface is mixed with the fresh water coming from the polar ice. This process also hampers the normal mixing and ultimately creates the ocean stratification. This trend is acutely visible in the subpolar North Pacific, the tropics and the existing basins' eastern margins. The research study makes it quite clear that the increasing ocean temperature is the key reason behind the rapidly decreasing oxygen level in the ocean.