The "The Blob" marine heat wave, which occurred between 2013 and 2016, warmed a significant area of surface waters in the northern Pacific, upsetting marine ecosystems around the West Coast, lowering salmon returns, and harming commercial fisheries.
Also, it sparked a flurry of studies on the dramatic warming of ocean surface waters.
But, as a recent NOAA study demonstrated, maritime heat waves also occur at great depths.
The first comprehensive analysis of bottom marine heat waves in the productive continental shelf waters surrounding North America was produced by a team led by NOAA researchers using a combination of observations and computer models, according to a paper that was published in the journal Nature Communications.
Scientists identify heat waves at bottom of the ocean
PAU BARRENA/AFP via Getty Images
Dillon Amaya, the primary author and a research scientist from NOAA's Physical Science Laboratory, noted that scientists have been examining marine heat waves at the sea surface for more than a decade, as per Phys.org.
For the first time, we can analyze how these dramatic events play out along shallow seafloors by going deeper.
Marine heat waves have a significant negative influence on the productivity and distribution of marine species of all sizes, including plankton and whales, throughout the world's ocean ecosystems.
As a result, a lot of work has gone into studying, tracking, and forecasting the occurrence, intensity, duration, and physical drivers of these events.
The majority of that study has been on temperature extremes near the ocean's surface, where there are more reliable satellite, ship, and buoy observations available.
Moreover, many physical and biochemical ocean features of delicate marine ecosystems can be detected by measuring sea surface temperatures, simplifying analysis.
Over the past century, the ocean has warmed by roughly 1.5C, absorbing nearly 90% of the extra heat caused by global warming.
Over the previous ten years, marine heatwaves have increased in frequency by around 50%.
Scientists have been working harder recently to examine marine heat waves across the water column utilizing the little information available.
The ocean floor along continental shelves, which serves as a crucial home for key commercial species, including lobsters, scallops, crabs, flounder, cod, and other groundfish, has not previously been the focus of research.
Because bottom-water temperature datasets are relatively rare, the scientists conducted the assessment using a data product called "reanalysis," which starts with available observations and uses computer models to "fill in the blanks" by simulating ocean currents and the influence of the atmosphere.
Using a similar method, NOAA scientists have been able to reconstruct global weather back to the early 19th century.
According to a groundfish survey released by NOAA Fisheries in 2021, Gulf of Alaska cod populations fell during The Blob, declining by 71% between 2015 and 2017.
However, a 2019 article by researchers from Oregon State University and NOAA Fisheries discovered that young groundfish and other marine life in the Northern California Current system flourished under the exceptional ocean conditions.
Additionally, abnormally warm bottom water temperatures have been linked to changes in the survival rates of young Atlantic cod, the spread of invasive lionfish along the southeast coast of the United States, coral bleaching and subsequent declines in reef fish, and the disappearance of near-shore lobster populations in southern New England.
The new heatwave appeared during the past few months, much like "the Blob."
The breezes that would otherwise mix and chill the ocean's surface were muted by a ridge of high pressure, as per NOAA.
The warmth, which is still quite recent and largely affecting the ocean's upper layers, could dissipate quickly.
Nate Mantua, a research scientist at the Southwest Fisheries Research Center, said, "It looks horrible, but it might also go away very fast if the abnormally persistent weather patterns that generated it shift.
Among the other effects of the preceding heatwave are:
The West Coast experienced its largest known hazardous algal bloom, which forced crabbing and clamming to be suspended for months.
Young California sea lions in their thousands are washing up on beaches.
Scientists from NOAA Fisheries recently held a special conference to discuss the impending heatwave and how to foresee and monitor its impacts.
Scientists are currently examining the effects noted during "the Blob" to contrast them with those of the impending heatwave.
