TIM eMagazine Vol . 3 Issue 1
Hotter , longer , more frequent -- marine heatwaves on the rise
Credits : Photo by Daniel Hjalmarsson ( Unsplash . com )
Researchers connect the data to show an accelerating trend for marine heatwaves in our oceans
University of New South Wales
The increasing number , intensity and duration of marine heatwaves is likely to have a profound impact on ocean ecosystems and the industries , like fisheries and tourism , that depend on them .
S ydney , Australia : An international study in Nature Communications co-authored by researchers from the ARC Centre of Excellence for Climate Extremes ( CLEX ) and the Institute of Marine and Antarctic Studies ( IMAS ) reveals globally marine heatwaves have increased over the past century in number , length and intensity as a direct result of warming oceans .
From 1925-2016 , the study found the frequency of marine heatwaves had increased on average by 34 % and the length of each heatwave had increased by 17 %. Together this led to a
54 % increase in the number of marine heatwave days every year . " Our research also found that from 1982 there was a noticeable acceleration of the trend in marine heatwaves ," said lead author , Dr Eric Oliver from Dalhousie University , Canada .
" 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 ."
Some recent examples show just how significant marine heatwave events can be .
In 2011 , Western Australia saw a marine heatwave that shifted ecosystems from being dominated by kelp to being dominated by seaweed . That shift remained even after water temperatures returned to normal .
In 2012 , a marine heatwave in the Gulf of Maine led to an increase in lobsters but a crash in prices that seriously hurt the industry ' s profits .
Persistent warm water in the north Pacific from 2014-2016 led to fishery closures , mass strandings of marine mammals and harmful algal blooms along coastlines . That heatwave even changed large-scale weather patterns in the Pacific Northwest .
More recently still , Tasmania ' s intense marine heatwave in 2016 led to disease outbreaks and slowing in growth rates across aquaculture industries .
The researchers used a variety of observational datasets to reveal the trend of increasing marine heatwaves , combining satellite data with a range century long datasets taken from ships and various land based measuring stations . They then removed the influences of natural variability caused by the El Nino Southern Oscillation , the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation to find the underlying trend .
" There was a clear relationship between the rise in global average sea-surface temperatures and the increase in marine heatwaves , much the same as we see increases in extreme heat events related to the increase in global average temperatures ," said co-author Prof Neil Holbrook from IMAS at the University of Tasmania .
" With more than 90 % 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 ." www . marineheatwaves . org
More information on marine heatwaves can be found at http :// www . marineheatwaves . org / Disclaimer : AAAS and EurekAlert ! are not responsible for the accuracy of news releases posted to EurekAlert ! by contributing institutions or for the use of any information through the EurekAlert system .
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