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The world’s oceans are suffocating. During the last century, marine heat waves have become more common and last longer. A new research carried out by scientists from Canada, USA The United States, the United Kingdom and Australia, published in the journal Nature , suggest that the annual number of days that a part of the ocean is experiencing a heat wave has increased by 54% from 1925 to 2016.
In general, scientists define a wave of marine heat like at least five consecutive days of unusually high temperaturesfor a particular ocean region or station. These extreme temperatures can be lethal to marine species such as corals, seaweeds and oysters, and can wreak havoc with fishing and aquaculture.
In the new study, the researchers looked for such recorded events in sea surface temperature data recorded up to 1900 and in satellite data since 1982. Not only heat waves are 34% more common on average, but they also last an average of 17% more.
This trend is mainly influenced by climate change caused by the warming of surface ocean waters , rather than by the large atmospheric-ocean climate patterns, such as the periodic warming and cooling of waters in the equatorial Pacific called the Southern Oscillation or the phenomenon of ‘El Niño’.
Eric Oliver, assistant professor of oceanography at Dalhousie University and lead author of the study, said that at the beginning of the 20th century, there were an average of two marine heat waves per year worldwide, but now there are three or four. While they used to last 10 days on average, they now last an average of 13 or 14 days.
The number of days of marine heat waves worldwide increased by 54% between 1925 and 2016, according to the study.
The findings are worrisome because marine heat waves can have lasting effects, Oliver says. “I’m not surprised, but it ‘s consistent with what we know about climate change and, therefore, it’s alarming.
“The whole package of global warming that we are experiencing is generally alarming because we are seeing impacts in our natural environment that in some cases we will not be able to undo,or it will take much longer to undo what it took to cause them,” says the scientist.
In 2016, a sea heat wave caused a severe bleaching of the Great Barrier Reef in Australia.
One of the largest marine heat waves in history, dubbed “The Blob”, was developed in 2014 and lasted until 2016, from Mexico to the Bering Sea. The patch brought marine creatures that usually live in warm waters to northern places and some scientists believe that it may have been responsible for the proliferation of toxic algae on the west coast.
In 2011, a wave of marine heat against Australia persisted for about a month, causing the death of fish and the closure of the profitable abalone fishery. The hot spot also caused the collapse of the seaweed forests of the area, which were permanently replaced by seagrasses.