Over 90% of excess heat caused by human emissions ends up in the oceans, which makes the study of ocean temperatures crucial for understanding climate change.
The good news is that a new study published by Science Advances gives us the most accurate and up-to-date measurements of ocean temperatures yet. The bad news is, oceans are warming faster than we previously believed, and accelerating.
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“We were able to extend our techniques back to the late 1950s and show that the rate of global warming has changed significantly in the past 60 years,” John Abraham, one of the study’s co-authors, wrote in the Guardian. “One main outcome of the study is that it shows we are warming about 13% faster than we previously thought. Not only that but the warming has accelerated.”
“The warming rate from 1992 is almost twice as great as the warming rate from 1960. Moreover, it is only since about 1990 that the warming has penetrated to depths below about 700 meters,” he wrote.
According to Abraham, they accounted for known biases in past measurements, compared the corrected data to advanced climate computer models and better data sources, and applied temperature models to greater areas.
The new study updates previous ocean temperature data by using more modern data collection techniques.
Developed in 2005, the Argo system deploys up to 3,500 floats across oceans that autonomously dive and resurface, collecting measurements up to a depth of 2,000 meters. After resurfacing, they relay that data to satellites.
Argo replaced expendable bathythermographs (XBT) that were capable of measuring ocean temperatures to depths of about 285 meters. In addition to the discrepancy in depth capabilities between the methods, XBTs were mostly used along shipping routes and in the northern hemisphere.
The gap in previous data collection showed in the study’s results:
“All ocean basins examined have experienced significant warming since 1998, with the greatest warming in the southern oceans, the tropical/subtropical Pacific Ocean, and the tropical/subtropical Atlantic Ocean,” the study said.
The depths at which oceans are warming is another grave concern, further indicating oceans are more vulnerable to global warming than previously believed which, in turn, will have more dire effects for life on Earth.
“The oceans are affecting weather and climate through more intense rains,” the authors wrote. “This process is a major reason why 2016 was the hottest year ever recorded at the Earth’s surface, beating out 2015 which was the previous record. Additionally, 2015 was a year with record hurricanes, heat waves, droughts, and wild fires around the world.”