Most of the “extra” heat that’s retained as a result of anthropogenic climate change ends up in the oceans (~90%). To put that another way, the world’s oceans are a giant heatsink, and they work to modulate the world’s air temperatures to a large degree.
With that in mind, the findings of a new study from the National Center for Atmospheric Research (NCAR) are somewhat unsettling — the world’s oceans may be storing as much as 13% more heat than was previously estimated.
“In other words, the planet is warming quite a lot more than we thought,” commented NCAR scientist Kevin Trenberth, co-author of the new study.
The findings are the result of a new analysis exploring the ways that ocean temperatures have been altered since 1960 — something that’s been somewhat difficult to date because of limited observation data. These findings were compared against the estimates published in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (in 2013).
The press release explains how the research was performed:
In more recent decades, measurements of ocean heat have increased, thanks to new observational techniques. In 2000, scientists began deploying a network of thousands of floats called Argo to profile conditions in the top layer of the ocean extending down 2,000 meters (6,562 feet). Argo achieved near global coverage in 2005, though some remote regions are still not sampled.
To fill the large gaps in the historical ocean temperature record, the research team used a combination of statistical techniques and model output to determine how useful a single observation can be for inferring information about the surrounding area, as well as how the temperatures in different parts of the world’s oceans relate to one another. They found that, in most regions, a single ocean observation could provide valuable information about conditions as far as 2,000 kilometers (1,243 miles) away.
To check if they were correct, they used Argo observations. At first, they chose data from only a small number of floats in the network to mimic the scarcity of observations that would have been available in the mid-20th century. Then they used their new technique to create an entire ocean temperature map based on those few observations. When they checked their map against the full complement of Argo observations, they found that their reconstruction tracked closely with reality.”
“The results were remarkable,” Trenberth noted. “They give us much more confidence about what the ocean heat content was, stretching back to the late 1950s.”
The results? Total warming between 1960 and 2005 was 337 zettajoules.
What’s particularly interesting about the findings, though, is that they show that increases were small until around 1980. After this point, they began to rise notably. Significant amounts of heat have begun to “seep deeper into the ocean layers” since 1990, according to the new work.
The new findings are detailed in a paper published in the journal Science Advances.
Image via Australian Commonwealth Scientific and Industrial Research Organization
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