Heatwaves are killing swathes of sea-life like “wildfires that take out huge areas of forest,” revealed scientists. There is a sharp increase in the number of heatwaves that are affecting the oceans of this planet.
The humanity is also under threat due to the damage caused to these hotspots because humans rely on the oceans for food, oxygen, protection of storm and the removal of carbon dioxide in the atmosphere causing climate-warming, as per the scientists.
The average temperature of the oceans is gradually increasing due to global warming. The new research systematically analyses the ocean heatwaves globally at the time of extreme temperature continuing for five days or more.
The number of heatwave days increased three times compared to the last couple of years studied and is also appearing more frequently and have become more severe and prolonged as per the research. There is more than a 50% increase in the number of heatwave days in 2016 compared with the 30 years between 1925 and 1954.
The kelp forests, seagrass meadows, and coral reefs that are the foundation species critical to ocean life, and provider of food and shelter to many others, are on the verge of extinction from California to Australia to Spain due to increased heatwaves.
Dan Smale at the Marine Biological Association in Plymouth, UK, who led the research published in Nature Climate Change said: “You have heatwave-induced wildfires that take out huge areas of forest, but this is happening underwater as well.”
“You see the kelp and seagrasses dying in front of you. Within weeks or months they are just gone, along hundreds of kilometres of coastline,” Dan added.
Dan’s team analyzed 116 research papers on eight well-studied marine heatwaves like the record-breaking “Ningaloo Niño” in 2011 that hit Australia and the hot “blob” in the north-east Pacific that persisted from 2013 to 2016. Smale said, “They have adverse impacts on a wide range of organisms, from plankton to invertebrates, to fish, mammals, and seabirds.”
The scientists revealed that hotspots, those harboring rich biodiversity or species almost reached their temperature limit or faced additional stresses like pollution or overfishing, are under threat from the north-east Atlantic to the Caribbean to the western Pacific. “A lot of ocean systems are being battered by multiple stresses,” Smale mentioned emphatically.
In some parts of the ocean, El Niño is a crucial factor in the temperatures rises whereas the effect of global warming on the same remains uncertain.
“The starting temperature is much higher, so the absolute temperatures [in a heatwave] are that much higher and more stressful,” explained Smale. Some mobile marine wildlife swims to cooler waters, but as the ocean heatwaves often strike large areas more rapidly than fish move, wildlife is in danger.
There are also “major socioeconomic and political ramifications” related to ocean heatwaves when lobster stocks were dramatically affected in the north-west Atlantic in 2012, and tensions created across the US-Canada border.
“This [research] makes clear that heatwaves are hitting the ocean all over the world … The ocean, in effect, is spiking a fever,” said Prof Malin Pinsky, at Rutgers University, US, and not part of the team. “These events are likely to become more extreme and more common in the future unless we can reduce greenhouse gas emissions.”
Dr.Éva Plagányi at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia also compared ocean heatwaves with wildfires. “Frequent big hits can have long-lasting effects,” she said. “This study shows that record-breaking events are becoming the new normal.”
A series of scientific papers published in the last week highlighted the damage caused to oceans by global warming. Pinsky and colleagues published their work disclosing the substantial reduction in sustainable fish catches in five regions by 15% to 35% including the North Sea and the East China Sea, and globally by 4%.
“We were stunned to find that fisheries around the world have already responded to ocean warming,” he said. The 2C climate change target set out in the Paris Agreement 2015 if achieved would save around fish catches of 10m tonnes per year, costing tens of billions of dollars.
Plagányi’s separate teamwork showed a reversal of whales’ recovery in the southern ocean due to climate change as the krill on which they feed got damaged. “Models predict concerning declines, and even local extinctions by 2100, for Pacific populations of blue and fin whales, and Atlantic and Indian Ocean fin and humpback whales,” they said.
“In the space of one week, scientific publications have underscored that unless we take evasive action, our future oceans will have fewer fish, fewer whales and frequent dramatic shifts in ecological structure will occur, with concerning implications for humans who depend on the ocean,” warned Plagányi.
