The world’s oceans in 2017 were the hottest ever recorded, scientists revealed in a new study published on Friday.
The findings were based on an updated analysis of the top 6,000 feet of the world’s seas by the Institute of Atmospheric Physics and the Chinese Academy of Science.
“The long-term warming trend driven by human activities continued unabated,” researchers said in the study, which was published in the journal Advances in Atmospheric Sciences. “The high ocean temperatures in recent years have occurred as greenhouse gas levels in the atmosphere have also risen.”
Owing to its “large heat capacity, the ocean accumulates the warming derived from human activities; indeed, more than 90 percent of Earth’s residual heat related to global warming is absorbed by the ocean,” according to the researchers. “As such, the global ocean heat content record robustly represents the signature of global warming.”
While ocean temperatures dropped slightly in 2016 because of a massive El Nino effect, the last five years were still the hottest recorded for the world’s oceans. The second hottest ocean year was 2015.
According to the study, heat increased in most regions of the world’s oceans. But temperatures in the Atlantic and southern oceans increased more than temperatures in the Pacific and Indian oceans.
Dr. John Abraham, a professor of thermal sciences writing in The Guardian, compared last year’s ocean heat increase to electricity use in China. The annual electrical generation in China would be 600 times smaller than the heat increase in the ocean, he noted.
The startling heating trend is dramatically represented on this graph developed by data from the Institute of Atmospheric Physics:
The research highlighted the “buffer” role the ocean can play in global warming as it absorbs both heat and carbon dioxide from the air, while also underscoring how climate change threatens to overwhelm that buffer.
A study late last year revealed that the low-oxygen “dead zones” in the world’s oceans had quadrupled in size. Suffocating dead zones are created as the oceans absorb increasing amounts of carbon dioxide from polluted air.
The new findings come just over a week after NASA declared 2017 to be the second warmest year on record.