Researchers warned in a new study that oxygen-starved ocean “dead zones,” where animals and plants are struggling to survive, have increased fourfold may not be reversible.
Growing “dead zones” are a symptom of climate change according the study, which was published in the journal Science. Rising ocean temperatures caused by an increased amount of greenhouse gases in the atmosphere mixed with sewage and agricultural runoff contamination closer to the coasts is choking ocean waters of oxygen and, in effect, making these areas nearly uninhabitable.
The research team from the Global Oxygen Network that conducted the study was created by the Intergovernmental Oceanographic Commission of the United Nations in 2016.
“Rising nutrient loads coupled with climate change – each resulting from human activities – are changing ocean biogeochemistry and increasing oxygen consumption,” the study reads. These deviations from a healthy, thriving ocean are “unsustainable and may result in ecosystem collapses, which ultimately will cause societal and economic harm.”
Scientists found that ocean “oxygen minimum” zones have expanded by an area about the same size as the European Union since the 1950s and that pockets of water completely lacking in oxygen have more than quadrupled since then. Oxygen barren – or hypoxic – zones have grown by 10 times, as well; increasing from less than 50 to 500 along coasts.
“(Ocean oxygen declines are) among the most serious effects of human activities on the Earth’s environment,” the study’s lead author and Smithsonian Environmental Research Center marine ecologist Denise Breitburg said in a statement, calling oxygen “fundamental to life in the oceans.”
“If you can’t breathe, nothing else matters,” Breitburg told The Associated Press. “As seas are losing oxygen, those areas are no longer habitable by many organisms.”
Oceans account for about half of the oxygen on Earth – making this deoxygenation a problem for everyone.
Scientists warn that low oxygen levels can stunt sea life and immune responses, decreasing ocean diversity and lowering survival rates. The study says that oxygen-starved areas can be saved if the effects of climate changed are reversed through interventions like instituting no-catch and no-fishing zones.
But unfortunately, even “ambitious emission reductions,” Breitburg said, might not prevent the predicted “further oxygen declines during the 21st century.”