11 April 2018

‘Devastating’ marine heatwaves increase by 34% in the last century

Warming oceans are causing a direct increase in the number of so-called marine heatwaves around the world, according to new research from a coalition of Australian academics.

These heatwaves, led by an increase in global temperatures, can have devastating impacts on marine wildlife, tourism and fishing.

The research is published in the journal Nature Communications by the newly launched ARC Centre of Excellence for Climate Extremes; the centre brings together five Australian universities to work on the science behind extreme weather events.

The scientists collated satellite data along with historical measurements from ship and land stations between 1925 and 2016. The method also took into account climate variability caused by natural phenomena, such as the El Niño and La Niña cycles.

They concluded that there was “a clear relationship” between average sea-surface temperatures and an increase in marine heatwaves. The frequency of these heatwaves climbed to 34 percent during the period under review, and 17 percent in duration. The bulk of this increase has also taken place in the past few decades, suggesting an accelerated trend.

Lead author Dr Eric Oliver said that “While some of us may enjoy the warmer waters when we go swimming, these heatwaves have significant impacts on ecosystems, biodiversity, fisheries, tourism and aquaculture. There are often profound economic consequences that go hand in hand with these events.”

These impacts include the mass die-off of marine mammals due to heat stress; coral bleaching; loss of kelp forests; permanently shifting ecosystems; and reducing the viability of local fishing industries.

Dr Lisa Alexander, one of the study’s co-authors, pointed out that human factors are a deciding factor: “With more than 90 percent of the heat from human-caused global warming going into our oceans, it is likely marine heatwaves will continue to increase. The next key stage for our research is to quantify exactly how much they may change.”

“The results of these projections are likely to have significant implications for how our environment and economies adapt to this changing world," she added.

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