Warmer Oceans Causing Loss of Oxygen in Waters Around the World, Says Study

Scientists posed another critical effect of climate change: the decreased amount of oxygen present in the world's oceans. A new study published in Nature showed the level of oxygen has dropped significantly over the last 50 years - and human activity is to blame. This could prove to be disastrous to marine life all over the globe.

According to an official report, oceanographers from GEOMAR Helmholtz Centre for Ocean Research Kiel conducted the study that's the most comprehensive analysis of oxygen reduction in the ocean so far. By studying all the historic oxygen data from all over the world as well as current measurements, the team discovered that the oxygen content in the ocean has decreased by about two percent in the last half-century.

It's also a global phenomenon: save for a few regions, the entire ocean across the Earth has lost oxygen. North Pacific, in particular, recorded the largest loss.

"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," co-author Dr. Lothar Stramma said. "For fisheries and coastal economies this process may have detrimental consequences."

After all, organisms under the sea need oxygen to survive as much as land-based animals do. Lead author Dr. Sunke Schmidtko pointed out that large fishes tend to avoid or not survive in areas with little oxygen. If the content continues its downward spiral, it's likely for marine life will take a major hit.

"Let's say it's another 2% in another 30 or 40 years, that will have a demonstrable impact," Rob Dunbar of Stanford University told TIME. "It's the whole food chain that gets affected by oxygen."

The phenomenon is largely due to the increasing temperature of the ocean. When water is heated, gases - including oxygen - escape the water and evaporate into the atmosphere. Additionally, warmer waters are lighter and less likely to sink and deliver oxygen to the deep sea.

As with many consequences of climate change, human activities play a major role in the ocean losing its oxygen. The rise of carbon dioxide concentration in the atmosphere consistently drive the temperature higher, heating ocean waters and leaving it less capable of containing oxygen.