Temperatures are already breaking records this year: Last month was the warmest May for the world’s oceans since record-keeping began in 1850, according to the National Oceanic and Atmospheric Administration.
The average ocean temperature throughout May was 1.53 degrees Fahrenheit, or 0.85 degree Celsius, higher than normal for the month.
For the planet as a whole May was the third warmest on record, the agency said on Thursday in its monthly climate update. North and South America had their warmest Mays on record.
In the United States, rising temperatures hit Washington State and northern Idaho especially hard. Two cities in Washington, Bellingham and Spokane, as well as smaller communities in the region, set records for their warmest Mays.
Why It Matters: Heat can harm ocean life and feed wildfires.
Warmer water tends to hold less oxygen, and large-scale fish die-offs may happen earlier in the year as the climate continues to warm. Last week, thousands of dead fish washed up on Texas beaches from unusually warm waters and lack of oxygen in the Gulf of Mexico. Across the ocean, higher temperatures contribute to coral reefs dying. The ocean also expands as it warms, raising sea levels even further on top of the added water from melting ice sheets.
Last month’s unusual heat contributed to Canada’s spate of wildfires. As wildfire smoke spread, air quality in western Canada and the northern Great Plains in the United States deteriorated significantly. More recently, the wildfire smoke reached cities in the Northeast and Midwest, causing Air Quality Index readings to skyrocket across much of the country.
Extreme heat can be dangerous to humans as well as wildlife. Over the next several days, parts of Florida, Louisiana and Texas are bracing for potential triple-digit temperatures, which put people at risk, especially if they work outdoors or lack air-conditioning.
Background: Climate change is joined by El Niño.
“With climate change and global warming, it’s been an interesting start to the season,” said Rocky Bilotta, a climatologist at NOAA, during a call with reporters.
Last week, the agency declared that the global ocean and atmosphere had officially entered the climate pattern known as El Niño, which occurs naturally when the surface of the Pacific Ocean becomes warmer than usual. The phenomenon generally leads to warmer temperatures globally, but Mr. Bilotta said that El Niño would most likely influence temperatures later this year and next year.
It’s hard to pinpoint a single cause for May’s heat, he said, but as the climate warms overall, increasingly hot temperatures and records are to be expected worldwide, both in the ocean and on land.
What’s Next: A year of extreme weather is likely.
Most of the United States can expect an unusually hot summer, with elevated drought and wildfire risks, according to NOAA. South Texas and much of New England are in for an especially hot July. On hotter days, plants lose more water to the atmosphere and dry out, worsening the effects of droughts and providing more fuel for wildfires.
Warmer temperatures can also lead to more evaporation from the ocean and other bodies of water. More water vapor in the atmosphere can then lead to heavier rain and snowfall, and fuel tropical storms.
For the next month, the northern Great Plains, the Mid-Atlantic region and the western Gulf Coast can expect more rain than usual, the agency forecast. Over the entire summer, the middle of the country can expect more rain while the Pacific Northwest, parts of the Southwest, the Great Lakes region and parts of the Mid-Atlantic should prepare for drought.
Longer term, El Niño conditions will almost certainly last at least until spring 2024, and could contribute to worse winter storms in the southern United States.