Temperatures are both risingand at sea, with climate experts sounding alarms about unprecedented sea surface temperatures in the North Atlantic.
Ofwarmer-than-average temperatures are expected to persist and could impact sea ice levels, fisheries and coral.
“We are in uncharted territory and we can expect more records to fall as El Niño continues to develop and these effects will extend into 2024,” said Christopher Hewitt, director of climate services for the World Meteorological Organization. “This is worrying news for the planet.”
The National Oceanic and Atmospheric Administration warned in late June that half of the world’s oceans could experience marine heat waves by September. Researcher Dillon Amaya said that in the decades of measurement by the organization’s Physical Sciences Laboratory, such widespread marine heat wave conditions had never been observed.
“Normally we would expect only about 10% of the world’s oceans to be ‘hot enough’ to be considered a marine heat wave, so to reach 40% or 50% even with prolonged warming is remarkable,” said Amaya.
Global sea temperatures in May and June were record highs for the time of year. The temperatures are also “much higher than anything the models predicted,” said Dr. Michael Sparrow, head of the World Meteorological Organization’s Division of World Climate Research.
Those high temperatures came in part before El Niño — which is associated with high ocean temperatures — even started, the European Union’s Copernicus Climate Change Service stressed in a July report.
With warmer temperatures, Antarctic sea ice reached “the lowest extent for June since satellite observations began, at 17% below average, breaking the June record by a significant margin,” Copernicus said. The region is usually considered relatively stable compared to the Arctic, Sparrow said.
High ocean temperatures also cause coral bleaching, which could leave coral vulnerable to deadly diseases, experts warned. NOAA calls coral bleaching “one of the most visible and damaging marine ecological consequences of persistently rising ocean temperatures.” Coral-based ecosystems act as nurseries for fish.
Rising ocean temperatures could also affect fisheries. As water temperatures rise, marine life moves toward the poles to stay cool, according to NOAA. This may mean that fish go beyond the reach of anglers. According to the agency, the marine fishing and fishing industry in the US provided approximately 1.7 million jobs and revenues of $253 billion in 2020.
Warmer ocean water can kill fish because it holds less oxygen than cooler water. In June,washed up along the coast of the Gulf of Texas due to a “low dissolved oxygen event”.
Marine heat waves can also produce “hot spots” of harmful algae, which produce toxic domoic acid that can build up in shellfish and make it dangerous to eat, the NOAA said.
According to NASA, about 90% of global warming takes place in the ocean. Scientists attribute the widespread heat of global ocean waters to human-induced climate change.