More than half of the world’s ocean surface has surpassed historic extreme heat thresholds on a consistent basis since 2014, according to a new study by the Monterey Bay Aquarium and published in the journal PLOS Climate.
The heat extremes, driven by climate change, put critical marine ecosystems like coral reefs, seagrass meadows and kelp forests at risk of collapse and threaten their ability to provide for local human communities, the researchers found.
“These dramatic changes we’ve recorded in the ocean are yet another piece of evidence that should be a wake-up call to act on climate change,” said Kyle Van Houtan, leader of the research team during his tenure as chief scientist for the aquarium. “We are experiencing it now, and it is speeding up.”
Researchers conducted the study by mapping 150 years of sea surface temperatures to find a fixed historical benchmark for marine heat extremes. They then analyzed how much and how often the ocean surpassed that heat benchmark.
Researchers discovered that more than half of the ocean saw heat extremes in 2014. The extreme heat trend continued over the next several years and reached 57% of the ocean in 2019, the last year measured in the study. By comparison, only 2% of the ocean surface saw such extreme temperatures at the end of the 19th century.