In estimations of ocean heat content — important when assessing and predicting the effects of climate change — calculations have often presented the rate of warming as a gradual rise from the mid-20th century to today. However, new research(link is external) from UC Santa Barbara scientists Timothy DeVries(link is external) and Aaron Bagnell(link is external) could overturn that assumption, suggesting the ocean maintained a relatively steady temperature throughout most of the 20th century, before embarking on a steep rise. The newly discovered dynamics may have significant implications for what we might expect in the future.
“There wasn’t an onset of an imbalance until about 1990, which is later than most estimates,” said DeVries, an associate professor in the Department of Geography, and a co-author on a paper that appears in the journal Nature Communications. According to the study, the period from 1950 to1990 saw temperature fluctuations in the water column but no net warming. After 1990, the study continues, the entire water column switched from cooling to warming.
These findings are the result of the addition of a largely underexplored factor in ocean heat content (OHC): deep ocean temperatures.
“Prior studies didn’t consider the deep ocean,” said Bagnell, a graduate scholar in DeVries’ laboratory and the paper’s lead author. Because of the challenges involved in getting temperature measurements in the deep ocean (below 2,000 meters) that region has gone largely unaccounted for, and data has been sparse. “There is some existing data, from research cruises and autonomous floats,” he added.
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