Warmer water holds less oxygen. I’m sure it will be fine.
Really high quality, informative video from Oregon State University above.
Low oxygen conditions that pose a significant threat to marine life are widespread and increasing in coastal Pacific Northwest ocean waters as the climate warms, a new study shows.
Researchers found that in 2021, more than half the continental shelf off the Pacific Northwest coast experienced the low-oxygen condition known as hypoxia, said the study’s lead author, Jack Barth of Oregon State University.
“We’ve known that low oxygen conditions are increasing based on single points of study in the past, but this confirms that these conditions are occurring across Pacific Northwest coastal waters,” said Barth, an oceanography professor in the College of Earth, Ocean, and Atmospheric Sciences. “The 2021 season was unusually strong compared to past years but with climate change, we are headed in a direction where this may be the norm.”
The new study, published recently in Nature Scientific Reports, is based on data collected by an unprecedented number of research vessels and autonomous underwater gliders that were collecting measurements in the ocean during summer 2021.
The vast amount of data gave researchers a more complete and nuanced understanding of hypoxia’s severity and spatial distribution in the coastal waters of the northern California Current, said Barth, who also serves as special advisor to OSU’s Marine and Coastal Opportunities program
“This picture has been needed for a long time by policymakers and fisheries managers who make decisions about ocean uses,” he said.
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A comparison of maps from past years shows a consistent trend of hypoxia increasing over time. Hypoxia was basically nonexistent, at 2%, from 1950 to 1980, about 24% from 2009 to 2018, and 56% in 2021. That trend persists even when researchers account for year-to-year variability, Barth noted. Researchers are now developing maps for 2022 and 2023 using the 2021 maps as a guide.
The findings provide policymakers and fisheries managers additional decision-making tools as ocean conditions continue to change, Barth said.
AIUI, there are two different mechanisms that create hypoxia events.
The “dead zone” that forms off of the Louisiana coast has been “traditionally” caused by fertilizer runoff (nitrogen, phosphorus) coming down the Mississippi, which then leads to algal blooms that cause them to consume more oxygen than they produce during the day.
Climate change can aggravate the dead zone in the Gulf (or northern lakes) from mass rain events that wash more fertilizer downstream. In the case of the waters off the PNW, changes in wind and currents can provide the upwelled natural-source nutrients that trigger algal overgrowth that makes algae a net consumer of oxygen.
And, of course, the other major mechanism to create hypoxia events is to overheat the water so it cannot hold as much oxygen. Why ocean water is heating up is left as a permanent conundrum for fossil fuel bought politicians.