Buzz
On February 17, 2017, people observe towering waves at El Porto beach as the strongest storm in six years hits Los Angeles. MARK RALSTON/AFP/Getty ImagesResearchers from Germany have confirmed what many had feared: Climate change is causing a reduction in the oxygen levels dissolved in the world's oceans, a shift that threatens marine life.
A team from the GEOMAR Helmholtze Centre for Ocean Research in Kiel, Germany, discovered that between 1960 and 2010, the oxygen content in the world's oceans dropped by 2 percent. The study also highlights that this oxygen loss is not evenly distributed across the oceans, meaning some regions have experienced a much more significant decline than others.
The Pacific Ocean, the largest in the world, experienced the greatest overall loss of oxygen, although the sharpest decline occurred in the Arctic Ocean, where climate change is severely affecting the environment. These findings were published in the February issue of the journal Nature.
Scientists had long suspected that dissolved oxygen levels were dropping, but earlier predictions were primarily based on regional ocean studies. The new GEOMAR research, however, marks the first global examination of ocean oxygen levels, making it the first deep-ocean study of this scope. The study highlights that the most severe effects of climate change are unfolding in the oceans.
Dissolved oxygen, as the name implies, refers to the oxygen dissolved in water, and it is vital for marine life. The issue arises from ocean physics: colder water retains more oxygen than warmer water, and freshwater holds more oxygen than seawater. As climate change warms the planet and glacial ice melts, ocean waters are becoming fresher and altered. This shift reduces the oxygen levels in the sea and disrupts ocean currents.
The ocean primarily gets its oxygen from the atmosphere, which enters the water at its surface. Ideally, dissolved oxygen would gradually mix down into the colder, deeper parts of the ocean. However, as the surface layers warm, oxygen is less likely to reach the deeper layers, leading to a reduction in the oxygen available to marine life at those depths.
What does this mean for the future of our oceans? It doesn't bode well. The researchers concluded that as oxygen levels fall, marine habitats, particularly ocean nutrient levels, will suffer, which could have a significant impact on coastal economies. If climate change continues, and oxygen levels keep dropping, the study suggests that by 2100, as much as 7 percent of the ocean’s oxygen could be lost.
Scientists found that the oxygen deficit could lead to the expansion of hypoxic areas, commonly known as "dead zones", in shallow waters, where marine life suffocates due to the lack of oxygen. The second-largest dead zone in the world currently exists in the northern Gulf of Mexico.
