Warming oceans wiping out marine life faster than thought. Here's why

As the effects of climate change continue to take a toll on the planet in the form of global warming, environmentalists have issued fresh warnings about the unusual rise in the sea surface temperatures in the North Atlantic, which could wipe out marine life on a biblical scale.

With a return of El Niño's, warmer than average temperatures are anticipated to remain, and could impact marine life and sea ice, according to CBS News report.

"We are in uncharted territory and we can expect more records to fall as El Niño develops further and these impacts will extend into 2024," World Meteorological Organization director of climate services Christopher Hewitt said Monday, adding that "this is worrying news for the planet."

The National Oceanic and Atmospheric Administration (NOAA) in late June warned that half of the world's oceans may experience marine heatwave conditions by September.

Research scientist Dillon Amaya said that in the organisation's Physical Sciences Laboratory's decades of measurement, such widespread high temperatures had never been seen.

"Normally, we might expect only about 10% of the world's oceans to be 'hot enough' to be considered a marine heatwave, so it's remarkable to reach 40% or 50%, even with long-term warming," said Amaya.

Temperatures in sea globally were recorded at their highest in May and June for the time of the year.

"The temperatures also much higher than anything the models predicted," Dr Michael Sparrow, head of the World Meteorological Organization's world climate research department, said.

The European Union's Copernicus Climate Change Service stressed in a July report that those high temperatures came, in part, before El Niño — which is associated with high ocean temperatures — even began.

With warmer temperatures, Antarctic sea ice "reached its lowest extent for June since satellite observations began, at 17% below average, breaking the previous June record by a substantial margin," according to Copernicus.

“The region is usually thought of as being relatively stable when compared to the Arctic,” Sparrow said.

Experts while warning said: "High ocean temperatures are also causing coral bleaching, which can leave coral vulnerable to deadly diseases."

NOAA regards coral bleaching "one of the most visible and damaging marine ecological impacts of persistently rising ocean temperatures." Coral-based ecosystems act as nurseries for fish.

Spiking ocean temperatures impact fisheries because marine life moves toward the poles to stay cool, said NOAA. 

It means fish are moving out the range of fishers, which supports 1.7 million jobs and $253 billion in sales in 2020 in US, according to the agency.

Warm oceans can kill fish because it holds less oxygen than cooler water. In June, thousands of dead fish washed up along the Texas Gulf Coast because of a "low dissolved oxygen event."

According to NOAA, marine heat waves can also produce hot spots of harmful algae, which produces a toxin, domoic acid, that can accumulate in shellfish and make it dangerous to eat.