At the end of the 19th century, only 2% of the ocean surface experienced extremely high temperatures, so-called “heat waves.” In 2019, “heat waves” were already observed on 57% of the ocean surface.
2014 must be recognized as the “point of no return” for the state of the ocean. Moreover, “heat waves” became the norm for the South Atlantic in 1998, and for the Indian Ocean in 2007. The area of ocean surface exposed to “heat waves” has increased the most, 5.3 times compared to the last century, in the Arctic, according to a study by scientists at the Monterey Bay Oceanarium (USA) in the journal PLOS Climate.
Another problem is the emergence of “death zones” with low oxygen levels in the North Pacific Ocean, according to an article in the scientific journal Science Advances. “It was important for us to understand the extent to which climate change affects the formation of oxygen-free “dead zones” that destroy the ecosystem and destroy food sources for marine life,” explained one of the authors of the work, Karl Knudson.
Over time, sedimentary rocks accumulate and are deposited on the seabed and the organisms living in these sediments disturb their structure, but in places where oxygen-free zones are formed, the structure is preserved, since there are no living organisms in them. The appearance of such zones does not necessarily require the process of melting glaciers, but rather a warm interglacial period, as is the case now.
Not only the ocean, but also coastal zones are suffering from climate change and anthropogenic factors. According to a study by The Conversation, an international team of experts, only about 16% of the world’s coastal regions are in relatively good condition, and many are so degraded that they cannot be restored to their original state. Many animal species, including those that migrate, rely on shorelines for breeding, feeding, and protection. Coastal areas are also where rivers are discharged, mangrove forests exchange nutrients with the ocean, and tidal flows are maintained. Coastal ecosystems are very complex and once lost, it is likely impossible to restore them to their original state.
