This month, parts of the Caribbean Sea and Gulf of Mexico were more than 5 degrees F warmer than normal. In recent days, a patch of the North Atlantic off the coast of Newfoundland, Canada — a region normally kept relatively cool by the Labrador Current — was an astounding 9 degrees F warmer than usual, according to Frédéric Cyr, a research scientist at Fisheries and Oceans Canada, a department of the Canadian government that oversees marine science and policy and manages the country’s fisheries.

Scientists pay close attention to marine heat waves because the world’s oceans are crucial for the planet’s ability to store heat. Studies have found that Earth’s oceans have absorbed about 90% of the heat trapped on the planet from greenhouse gas emissions since 1970.

As climate change causes the world to warm, sea surface temperatures can offer clues about the health of these bodies of water. As such, the extent of the heat wave unfolding in the North Atlantic, its severity and its duration are all cause for alarm, Ryan said.

“As a scientist, you know this is well within the range of what climate models predict would happen at some point, but to see it actually happening is kind of scary,” she said.

Some impacts are being felt already. The soaring sea surface temperatures off Florida are imperiling the region’s coral reef. Scientists have warned that the heat wave could trigger mass die-offs of coral, which could have profound implications for marine ecosystems in the area.

Elsewhere in the Atlantic, researchers are tracking changes in the distribution of fish as the waters warm. Ryan said certain tropical fish species are expanding their range, venturing further north than normal. Other animals, such as whales, are shifting their movements to match their prey.

“We’re seeing some animals compress their habitats, or some shift latitudinally if they’re capable,” Ryan said. “Or, like the corals in Florida, they just have no chance and die off.”