Oxygen loss in oceans caused by climate change

Posted on April 29, 2016 12:03 am

In a study published in Global Biogeochemical Cycles, there’s evidence of reduction in the amount of oxygen present in oceans in some parts of the world. The loss of ocean oxygen is predicted to be more prevalent in larger sections of oceans between 2030 and 2040 and data will be comprehensive enough for researchers to see what parts of the ocean are being affected by human-caused deoxygenation. Decline in ocean oxygen will leave fish, crabs, squid, sea stars and other marine life to face struggle in breathing. Matthew Long from National Centre for Atmospheric Research(NCAR) was of the view that loss oxygen in the ocean has been considered as one of the serious side effects of warming atmosphere.“Oxygen varies naturally in the ocean quite substantially,” Matthew Long, lead author of the study. “Without any human-driven climate change we could expect oxygen levels at a particular location to go up and down in such a way that low levels may be persistent for a number of years, followed by a period of high levels.”That means that, if scientists today measure oxygen levels in part of the ocean for a short period of time and observe a decreasing trend, they can’t say for sure if that trend is caused by climate change, Long said. But that should change by 2030.“While there’s some ambiguity now, in the not too distant future, that ambiguity will be eliminated in places where we have long records,” he said.Scientists have explained that warming surface waters absorb less oxygen. The oxygen that is absorbed faces more trouble in travelling deeper into the ocean.

Deoxgenation due to climate change is already detectable in some parts of the ocean. New research from NCAR finds that it will likely become widespread between 2030 and 2040. Other parts of the ocean, shown in gray, will not have detectable loss of oxygen due to climate change even by 2100.Image by Mathew Long of NCAR
Deoxgenation due to climate change is already detectable in some parts of the ocean. New research from NCAR finds that it will likely become widespread between 2030 and 2040. Other parts of the ocean, shown in gray, will not have detectable loss of oxygen due to climate change even by 2100.Image by Mathew Long of NCAR

The researchers have used the NCAR-based Community Earth System Model in order to study the impact of climate change.They have used results of a project in which the model ran for more than two dozen times for the years 1920 to 2100 on the Yellowstone supercomputer. Using the simulations to study dissolved oxygen, the researchers were able to have a better idea on how much concentrations must have varied in the past naturally.The data unveiled that deoxygenation owing to climate change could already be detected in the southern Indian Ocean and parts of the eastern tropical Pacific and Atlantic basins. They have also mentioned that more widespread detection of deoxygenation is possible between 2030 and 2040.But there were some parts where deoxygenation caused by climate change was not evident even by 2100, said the researchers.”Loss of oxygen in the ocean is one of the serious side effects of a warming atmosphere, and a major threat to marine life,” said NCAR scientist Long.Overall,As the planet warms, the oceans are absorbing a lot of heat so much so that ocean heat sinks were responsible for the slowdown in atmospheric temperature increase earlier this century. But warmer waters, as the study explains, don’t absorb as much oxygen as cooler waters do. Higher surface water temperature also “stratifies the ocean,” the study states: As the surface water warms, it becomes more buoyant and less dense, meaning that it mixes less and oxygen at the surface doesn’t make it to the middle of the ocean.It’s that mixing that’s responsible for sustaining oxygen levels at depth.Lack of oxygen is a serious problem for ocean ecosystems. Just like animals on land, marine creatures like fish and crabs depend on oxygen for survival.I believe many species won’t survive if these findings by researchers come to pass.

Contador Harrison