Fossil fuels behind extreme ocean temperatures, study says

For 450 straight days in 2023 and 2024, ocean temperatures hit record highs.

According to a new study, the world’s oceans are warming four times faster than they were in the late 1980s, and the burning of fossil fuels is behind the dramatic acceleration, Danielle Bochove reported for Bloomberg.

“With climate change, it’s the oceans that set the pace,” Christopher Merchant, lead author and an ocean and Earth observation scientist at the University of Reading, told Bloomberg.

Merchant said that without substantial moves to cut fossil fuel use, ocean temperatures in the coming decades could rise “by a significant margin” compared with the increase between the 1980s and today.

The study is one of the first to provide hard evidence of the link between the rapid increase in ocean temperatures and fossil-fuel use.

While some of the warming can be attributed to El Niño, a natural effect that refers to above-average ocean surface temperatures, the intense heat seen across the world’s oceans in 2023 and 2024 was too extreme to be explained by that weather pattern alone. According to the study, 44 percent of the record heat was due to oceans absorbing heat more rapidly.

The consequences of this unprecedented warming will be enormous — among other ways, for the economies and food security of millions of people.

Fueled by greenhouse gas emissions, ocean warming is beginning to alter the habitats of tuna, causing tuna to move outside the jurisdictions — or Exclusive Economic Zones (EEZs) — of many Pacific Islands. Recently, a team of experts — led by Conservation International’s Johann Bell — found that an exodus of tuna could cut the average catch by a staggering 20 percent in 10 Pacific Island states.

According to a study published in Nature Sustainability, catch reductions of this magnitude could result in a collective loss of US$ 140 million per year by 2050 and cost some of these island nations and territories up to 17 percent of their annual government revenue.

“Currently, many of the tropical areas with warm waters preferred by skipjack, yellowfin and bigeye tuna are within the EEZs of Pacific Island states,” said Bell, who leads the tuna fisheries program at Conservation International.

“But as the ocean continues to warm, the conditions preferred by tuna will be located farther to the east, including in the high seas, which are not governed by any one country.”

Read the full Bloomberg story here.

Mary Kate McCoy is a staff writer at Conservation International. Want to read more stories like this? Sign up for email updates. Also, please consider supporting our critical work.