Oxygen loss in the global ocean could become apparent by the 2030s, according to a new study. Climate change is expected to radically alter the concentration of the life-sustaining gas deep within oceans.
National Center for Atmospheric Research (NCAR) investigators studied how oxygen levels are shifting in waters around the globe.
Global warming could lead to a diminished ability of oceans to hold on to oxygen. Currently, reduced concentrations of oxygen from climate change are indiscernible from the natural fluctuations. By the 2030's, losses of the dissolved gas, due to climate change, should be noticeable in oceans around the world, researchers determined.
As oxygen levels in the global ocean are reduced, marine life, including plants and animals, will find breathing more difficult. The challenge has been to determine the ratio of oxygen deprivation due to climate change, compared to natural cycles in nature.
"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," Matthew Long of NCAR said.
Oxygen in the global ocean comes from the atmosphere, as well as being released by phytoplankton in the water undergoing photosynthesis.
Global warming is expected to raise the temperature of surface water, lowering its average density. This is predicted to reduce the rate at which this water sinks, decreasing the quantity of oxygen brought from the surface to greater depths.
Researchers carried out computer simulations to model how levels of oxygen will be altered by global warming through the end of the century. These simulations revealed that oxygen loss in oceans will become quite evident in the next two decades.
Living beings in the depths of the ocean could find breathing in these conditions to be labored. The phenomenon could also lead to an increase in the extent and severity of dead zones, where life is scarce or non-existent. As the effects of climate change become more pronounced, natural variations in oxygen concentrations will become overwhelmed, researchers concluded.
Analysis of how oxygen levels in oceans are affected by global warming was published in the journal Global Biogeochemical Cycles.