Two studies focus on ocean waters as heat sink

Science : Although Earth’s oceans are as important to global climate as the atmosphere, they have not been as well studied. Two areas of particular concern are the waters of the Southern Hemisphere and those of the deep ocean, below 2000 m. Paul Durack of Lawrence Livermore National Laboratory and colleagues used satellite measurements of sea-level height to estimate ocean temperature—as water warms, it expands. According to their model simulations, estimates of the heat stored in the upper 700 m of the ocean since 1970 have been too low , due largely to the poor sampling data from the Southern Hemisphere. Another group of researchers, led by William Llovel of the Jet Propulsion Laboratory, looked at warming in the deep ocean since 2005. Because most temperature data come from buoys, more is known about water temperature in the top 2000 m, and much less is known about the temperature of the rest of the ocean, which can descend as deep as 6000 m. Comparing the available data with global sea-level rise since 2005, the researchers estimate that the deep ocean has barely warmed over the past decade. Both studies point up the need for more data, which may soon be provided by a new fleet of research buoys, dubbed Deep Argo.