Scientists are worried that an El Niño–prolonged ocean heat-up off the coast of England and Ireland will result in massive death tolls for sea life, along with other terrible outcomes. That’s because temperatures in the North Sea are already 5 degrees above normal, according to the Guardian.

As conditions mount for continued ocean warming, the experts fear that sea life could be killed off like forest dwellers are destroyed during wildfires.

It’s all part of the fallout from an overheating planet.

What’s happening?
Ocean warming in the North Sea has been ongoing for decades, the Guardian reports. The mercury rose to a record high this spring, based on recordings dating to the 1850s. It’s part of a trend of ocean warmups during the past three decades.

Sea surface temperatures around the planet have been measured at all-time highs, peaking at 70.2 degrees Fahrenheit, according to the Guardian.

“While marine [heat waves] are found in warmer seas like the Mediterranean, such anomalous temperatures in this part of the north Atlantic are unheard of,” University of Bristol professor Daniela Schmidt told the Guardian.

Since water covers more than 70% of the Earth’s surface, the ocean catches a lot of solar energy. The sea can move that heat around the globe as part of the natural climate balance. But human-caused overheating is overloading the system, according to Climate.gov. Experts warn that more than 90% of excess heat is absorbed in the oceans.

“Heat … stresses marine organisms. In other parts of the world, we have seen several mass mortalities of marine plants and animals caused by ocean heat waves, which have caused … losses, in fisheries income, carbon storage, cultural values, and habitat loss,” Schmidt said in the Guardian’s report.

Kelp (which stores carbon), fish, and oysters are among species being monitored.

Why could it get worse?
A combination of factors, including planet-wide overheating and El Niño, are involved, experts report in a video shared by the Guardian. During an El Niño, weakened trade winds allow warm water to be pushed east, toward the west coast of the Americas, disrupting oceans around the world.

“But, as this is happening below the surface of the ocean, it will go unnoticed,” Schmidt said to the Guardian.

Droughts and floods are disasters mentioned in the clip as possible repercussions on land from the ocean’s warming.

What’s being done to help?
Piers Forster, a climate physics professor at the University of Leeds, told the Guardian that “human-induced” warming is a priority problem.

So, efforts to reduce air pollution are key to cooling our waters. Experts are monitoring Antarctic sea ice and other metrics to gauge the warming’s severity.

“If [ocean warming] carries on through summer, we could see mass mortality of kelp, seagrass, fish, and oysters,” Dan Smale, from the Marine Biological Association, said in the Guardian report.