One of the impacts that global warming has on the oceans are pockets of heatwaves. Oceanographer Andrew Leising from the National Oceanic and Atmospheric Administration (NOAA) calls his online marine heatwave tracker to "Blobtracker."
In August, a blob called NEP20b off the coast of California grew to 3.7 square miles, roughly the size of Canada. The marine heatwave was 39 degrees Fahrenheit warmer than usual, said Leising. By September, NEP20b was the biggest warm blob detected by satellite imaging since the 1980s.
Named after the classic "Blob" movie, a creature that consumed everything and everyone it encountered, the first ocean blob lasted between 2013 and 2016. From the California coast all the way north to Alaska, the marine heatwave drastically affected marine life and seabirds.
Fish populations such as cod collapsed and tuna migrated to Alaska for more suitable conditions. Seabirds on the west coast starved from the lack of prey and whales were found in crab wishing lines or near ships. Invasive species such as the glowing tropical sea pickles were found further north than usual.
Blob 2.0
The second blob, dubbed Blob 2.0, was detected last year. Scientists believe that the current blob is a continuation of the 2019 marine heatwave. They fear that the warm water may stay around for years and negatively impact marine wildlife and their predators again.
Although NEP20b appears to be shrinking, said Leising, the impact may last for several years. He added that the pandemic has also hindered researchers from collecting data on current fish populations.
A recent study published in the journal Science analyzed the high impact that human-induced global warming has on marine heatwaves. Researchers from the University of Bern noted that anthropogenic activity has increased the frequency of marine heatwaves by ten times. Without humans contributing the climate change, the warm ocean blobs would only occur once every hundred to thousands of years as they did during preindustrial times.
Impact of Marine Heatwaves
In another study found in the journal Global Change and the Future Ocean, scientists projected that eventually, parts of the world may have permanent marine heatwaves by 2100. Over time, they wrote, extreme temperatures will lead to "irreversible loss of species or foundation habitats, such as seagrass, coral reefs, and kelp forests." Other warm blobs have been detected in Northern Australia, the Gulf of Alaska, and the Bearing Sea since 2016.
The NOAA and other marine scientists continue to develop projected models of marine heatwaves in the future. Scientist Michael Jacox said, "I don't think we're at the point where we can predict them. But once they show up the models predict if things will stay warm."
Leising explained that marine animals have their absolute thermal limits similar to humans. Since many sea creatures are cold-blooded, their behavior and migration patterns change according to the temperature underwater. Also, cold-blooded species may adjust to warmer temperatures at first 'up until some breaking point at which they absolutely break down and die."
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