The Ocean Has a 'Fever.' These Are the Symptoms

The Pacific isn't just warm right now; scientists say a giant swath of it is in a full-blown "fever." The massive marine heat wave, formed as a North Pacific hot spot merged with warming tied to a developing super El Niño along the equator, covers about 13.5% of Earth's surface, stretching from the Philippines to Peru and toward Hawaii and California—big enough to reshape weather far from the water, the Washington Post reports. Forecasters say the heat is already helping fuel Super Typhoon Bavi in the western Pacific and could help set up a strong heat dome over the western US in mid-July, heightening fire risks from Arizona to Colorado.

As the ocean absorbs heat, the water expands, with implications for global sea levels. Off California, climate scientist Daniel Swain warns that sea levels this winter could run 6 inches to 2 feet above normal—with storms pushing that surge to 2 to 3 feet higher, raising the odds of disruptive coastal flooding, the Post reports. Eventually, the heat is released into the atmosphere, "significantly altering weather patterns," per the Guardian. "Months and months of warmth could mean stark impacts this winter and next spring," climate scientist Dillon Amaya tells the Post. Globally, marine heat waves now cover more than 37% of the ocean, triple the share seen in the late 1980s.