The world's oceans experienced their hottest June on record last month, with nearly 40 percent of ocean areas in marine heatwaves. This warming has contributed to deadly heat on land across the United States and Europe.
The European Union’s Copernicus Climate Change Service reported that Western Europe saw its hottest June ever recorded. Dozens of cities in the United States recorded temperatures over 100 degrees Fahrenheit during Fourth of July celebrations, and dozens died from heat in New Jersey alone. European authorities linked thousands of deaths to heat at the end of June.
Oceans have absorbed 90 percent of excess heat from global warming. Waters exchange heat and moisture with the atmosphere, driving hotter temperatures and extreme weather. A recent study found that at least a fifth of heatwaves on land begin in the ocean.
Scientists noted connections between ocean heat and specific events. Warm Mediterranean Sea temperatures likely fueled European heatwaves. A marine heatwave off Florida’s Gulf Coast raised air temperatures and humidity. Unusually warm Pacific waters may have set up a heatwave forecast for the central and northern United States.
An emerging El Niño pattern in the Pacific adds to the risks. It has an 81 percent chance of becoming one of the strongest in history, according to the National Oceanic and Atmospheric Administration. This could keep global temperatures elevated into early next year.
