Are the Oceans Running Out of Oxygen?

An alarming new study conducted by the National Centre for Atmospheric Research (NCAR) has concluded that some parts of the world’s oceans are already suffering from a lack of oxygen. Even more worryingly, it predicts that significant regions of the world’s oceans will show obvious oxygen deficiencies by 2030 or 2040, and that by 2100 most parts will have been affected.

The study, which was published in the journal American Geophysical Union (AGU), draws concrete links between climate change and deoxygenation of the oceans for the first time in an academic study. The data adds to concerns that a dearth of oxygen will adversely affect a whole host of marine life beneath the waves, causing them to relocate to a new habitat or perhaps even die out altogether due to asphyxiation.

Furthermore, it’s also thought that the effects of the manmade deoxygenation could span years, decades or even longer, meaning that even if we begin addressing our carbon footprint concerns now, it could be too late to prevent disruption and destruction to underwater ecosystems far into the future.

Climate Change or Natural Temperature Flux?

Since all of the oxygen in the ocean begins life at its surface – whether that be through the contributions of tiny phytoplankton who react with the sun’s rays or direction absorption from the atmosphere – it only makes sense that an increase in global temperatures would raise the surface temperature of the water, too.

Scientists already know that colder water produces more oxygen, and the problem would be exacerbated by the fact that warmer air expands and rises to the top, discouraging the dispersion of oxygen throughout the ocean’s depths. However, the ocean is constantly moving, making it hard to determine whether the temperature increases in the accompanying deoxygenation are related to climate change or more natural factors.

 “Loss of oxygen in the ocean is one of the serious side effects of a warming atmosphere, and a major threat to marine life,” explained Matthew Long, scientist at NCAR and lead author on the study. “Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it's been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the impact from climate change to overwhelm the natural variability.”

Computer Modelling for Accurate Predictions

The inaccessible nature of the ocean means that it’s very difficult to gain accurate information about how climate change affects oceanic behaviour. While coral reefs are one archive of climate change underneath the waves, the data they provide is unreliable and unspecific. What is needed are more accurate measurements and models.

In order to determine whether or not the loss of oxygen was being caused by climate change or naturally occurring temperature fluctuations and wind patterns, Long and his team used the Community Earth System Model, a sophisticated computer programme capable of predicting meteorological events and phenomenon based upon weather monitoring in conjunction with climate change.

The team ran data from 1920 to 2100 more than 20 different times, adjusting the temperature at the outset of the programme by mere degrees each time. The differences in the parabolas of the programmes caused by these discrepancies provided interesting information regarding the topics of meteorological variability. They concluded that while certain areas of the ocean are already experiencing damagingly low levels of oxygen, many others will follow suit in the next 25 years.