Climate change

New study warns that ocean heat waves become 'new normal'

Written by Oceanographic Staff

A new study, published on Tuesday, argues that ocean heat waves have been the new normal throughout the world since 2014.

The study, conducted by a team of researchers from the New Monterey Bay Aquarium was published in the journal PLOS Climate and found that the majority of the ocean’s surface has experienced ocean heat waves since 2014.

By mapping 150 years of sea surface temperatures from 1870 until 2019, the team tried to establish an index of extreme marine heat. For 2019, this index reported that 57% of the global ocean surface recorded extreme heat. In comparison, at the end of the 19th century, only 2% of ocean surfaces around the world experienced extreme heat events. Establishing that extreme heat events have happened on a regular basis since 2014, the study further said that “2014 was the first year to exceed the 50% threshold of extreme heat thereby becoming ‘normal’, with the South Atlantic (1998) and Indian (2007) basins crossing this barrier earlier”.

Decadal evolution of frequency of extreme marine heat from 1980 to 2019:

These ocean heat waves increase the risk of coral bleaching events, ocean acidification, the collapse of kelp forests, seagrass meadows and other marine ecosystems and exacerbate the need for immediate action to combat climate change and reduce emissions. Dr. Kyle Van Houtan, chief scientist for the New Monterey Bay Aquarium, explained: “Climate change is not a future event. The reality is that it’s been affecting us for a while. Our research shows that for the last seven years more than half of the ocean has experienced extreme heat.”

He added: “Today, the majority of the ocean’s surface has warmed to temperatures that only a century ago occurred as rare, once-in-50-year extreme warming events. When marine ecosystems near the tropics experience intolerably high temperatures, key organisms such as corals, seagrass meadows, or kelp forests can collapse. Altering ecosystem structure and function threatens their capacity to provide life-sustaining services to human communities like supporting healthy and sustainable fisheries, buffering low-lying coastal regions from extreme weather events, and serving as a carbon sink to store the excess carbon put in the atmosphere from human-generated greenhouse emissions.”

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Photography courtesy of Unsplash.

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