Larry O'Hanlon

Despite mixed signals from warming ocean surface waters, a new re-analysis of data from the depths suggests dramatic warming of the deep sea is under way because of anthropogenic climate change. The scientists report that the deep seas are taking in more heat than expected, which is taking some of the warming off the Earth’s surface, but it will not do so forever.

"Some of the heat (from human-caused global warming) is going into melting sea ice and heating the surface, but the bulk is going into the oceans,” said climate researcher Kevin Trenberth of the National Center for Atmospheric Research, a coauthor on a new research paper reporting on the deep ocean warming in the journal Geophysical Research Letters.

The study involved the bringing together of a diverse suite of data, ranging from satellite measurements of the surface waters to ship observations at all depths, instruments mounted on elephant seals, ARGO profilers (a large collection of small, drifting-robotic probes deployed worldwide), and data-gathering instruments moored in place. The data include temperature, salinity, depth, and altimetry of the ocean surface, going back decades.

Piecing together different kinds of data from different times and sometimes from sparse data sets was the key challenge, Trenberth explains, but that is the specialty of his coauthors at the European Center for Medium Range Weather Forecasts in the U.K