Most of the oceans have experienced extreme heat since 2014

More than half of the ocean’s surface has exceeded a historical threshold for extreme heat on a regular basis since 2014, according to temperature data collected over more than a century, in a study published by Plos Climate.

The research, led by the Monterrey Bay Aquarium (United States), indicates that this trend continued in the following years, reaching 57% of the ocean in 2019, the last measured in the study.

Excessively warm ocean temperatures “driven by climate change are the new normal” – the document adds – and these extremes of heat increase the risk of collapse of crucial marine ecosystems.

Among them he cites coral reefs, seagrass beds and kelp forests, altering their structure and function, and threatening their ability to continue providing life-sustaining services to human communities.

Using historical records, scientists determined mean ocean surface temperatures between 1870 and 1919 to establish a fixed reference point for marine heat extremes, then observed how often and where in the ocean that threshold was exceeded. limit.

Using this benchmark, only two percent of the ocean surface was experiencing extremely warm temperatures at the end of the 19th century.

Team manager Kyle Van Houtan said climate change “is not a future event” but “has been affecting us for a long time” and this research shows that over the last seven years more than half the ocean has experienced extreme heat.

“Today, most of the ocean surface has warmed to temperatures that only a century ago occurred as rare once-in-50-year extreme warming events,” Van Houtan said.

For the scientist, these drastic changes constitute one more proof that should be a wake-up call to act in the face of climate change, since “we are experiencing it now, and it is accelerating”.

When marine ecosystems near the tropics experience “intolerably high” temperatures, key organisms such as corals, seagrass beds or kelp forests can collapse,” Van Houtan said.

Altering the structure and function of ecosystems compromises their ability to provide life-sustaining services to human communities.

Van Houtan listed, among other functions, supporting healthy and sustainable fisheries, buffering low-lying coastal regions against extreme weather events, and acting as a carbon sink to store excess carbon put into the atmosphere by greenhouse gas emissions. greenhouse effect.