Today's Edition
ABU DHABI (ALETIHAD)
A climate pattern centred in the North Pacific can raise or lower oxygen levels across the world’s oceans, potentially changing marine habitats within a few years and producing delayed responses in deeper waters, according to new research from NYU Abu Dhabi.
The study, published in Geophysical Research Letters, found that changes in Pacific climate conditions affect ocean oxygen in two distinct ways. Oxygen levels in shallower waters can change relatively quickly, potentially shrinking or expanding marine habitats, while deeper waters respond more slowly and can retain the effects of past climate conditions for years.
The researchers analysed global ocean observations spanning nearly 60 years to examine how the Pacific Decadal Oscillation (PDO), a natural climate pattern that varies over periods of years to decades, influences oxygen levels around the world.
Changes in the PDO can rapidly shift the boundaries of low-oxygen waters, potentially shrinking or expanding marine habitats. Deeper waters respond to the accumulated effects of past climate conditions.
''The PDO can bring oxygen gains as well as losses,” said Zouhair Lachkar, Senior Research Scientist at NYU Abu Dhabi. “How quickly this climate pattern changes matters, because it can reshape the habitat available to marine life within just a few years.”
Deeper oxygen minimum zones, which are large regions where oxygen is naturally scarce, respond more slowly. Their oxygen-poor cores expand or contract as the effects of past climate conditions accumulate, with delays of around a decade.
The strongest relationship was found in the North Indian Ocean. That finding has particular relevance for the northern Arabian Sea and neighboring Sea of Oman. Changes in oxygen conditions could affect habitats supporting regional fisheries.
The fluctuations can also temporarily mask or strongly accelerate climate-driven oxygen loss, known as ocean deoxygenation, over records spanning two to three decades.
“A period of rising oxygen does not mean that long-term deoxygenation has stopped,” said Lachkar. “Natural climate variability can conceal that decline or reinforce it, making sustained monitoring essential, even in waters far from the Pacific.”
