A study published in the journal Global Biogeochemical Cycles revealed that the oceanic oxygen levels have been reduced due to climate change. While the effects may not yet be very obvious now, researchers at the National Centre for Atmospheric Research (NCAR) in Boulder, Colorado warn that the effects may be evident between 2030 through 2040.

“Loss of oxygen in the oceans is one of the serious side effects of a warming atmosphere and a major threat to marine life,” says lead author Matthew Long, a scientist at researchers at the NCAR. “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 effect from climate change to overwhelm the natural variability.”

The research team explains that the ocean gets its oxygen from the atmosphere or from phytoplankton that releases oxygen through photosynthesis. However, warm surface waters absorb less oxygen, which can have serious consequences on all marine life.

oceanic oxygen

By the 2030s, declining oxygen levels will likely be evident in many of the world’s oceans. Credit: NCAR

Based on the Community Earth System models developed, the researchers found that deoxygenation due to climate change is already occurring in the Atlantic basins. While majority of the world’s oceans would suffer from deoxygenation in the 2030s, the scientists assert that a few parts in the ocean, including some regions of Africa’s east coast, Australia, and Southeast Asia, would not experience deoxygenation until 2100.

oceanic oxygen

Marine life moves much more slowly in a low-oxygen ocean. Credit: NOAA

Still, further studies and observations are urgently needed, the researchers point out. Nevertheless, the new study has already given us a glimpse of the effects of climate change on the world’s oceans.

“We need comprehensive and sustained observations of what’s going on in the oceans to compare with what we’re learning from our models, and to understand the full effect of a changing climate,” concludes Long.