Climate Change

Ocean heatwaves likely to increase as planet warms: study

Marine heawaves have already become longer-lasting and more frequent, extensive and intense and this trend is likely to accelerate under further global warming, says a new study

By DTE Staff
Last Updated: Thursday 16 August 2018
Coal reefs and marine heatwaves
Marine heatwaves in 2016 and 2017 off eastern Australia killed off nearly half of the shallow water corals of the Great Barrier Reef. Credit: U.S. Fish and Wildlife Service Headquarters/Flickr Marine heatwaves in 2016 and 2017 off eastern Australia killed off nearly half of the shallow water corals of the Great Barrier Reef. Credit: U.S. Fish and Wildlife Service Headquarters/Flickr

In 35 years, the number of ocean heatwave days has doubled and is likely to increase five times if climate change continues at current scale, warn scientists in a recently published study in the journal Nature.

In the past few decades, marine heawaves have already become longer-lasting and more frequent, extensive and intense. The researchers say this trend is likely to accelerate under further global warming

Had it not been for the oceans that absorbed most of the extra heat generated by climate change, air temperatures would be tens of degrees Celsius higher. Marine heat wave also affects the ocean's ability to soak up greenhouse gases.

Marine heat waves can also damage shallow-water ecosystems that also store CO2. But ocean heatwaves are said to receive lesser scientific attendance than heat waves over land. The study said that between 1982 and 2016, the number of “marine heatwaves” roughly doubled. Prolonged periods of extreme marine heatwaves can damage kelp forests and coral reefs, and can also harm fish and other marine life.

The researchers define marine heatwaves as extreme events in which sea-surface temperatures exceeded the 99th percentile of measurements for a given location. Most marine heatwaves last longer than heat wave over land because oceans both absorb and release heat more slowly than air.

Marine heatwaves in 2016 and 2017 off eastern Australia killed off nearly half of the shallow water corals of the Great Barrier Reef.  It also permanently pushed commercial fish species into colder waters. Marine heatwaves are likely to increase even if we manage to cap global warming by two degrees Celsius, as called for in the Paris climate treaty.

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