Climate Monster Found Lurking in Ocean Depths

An article appearing in the November 1 issue of Science magazine analyzes mid-depth Pacific Ocean temperatures going back 10,000 years and finds a drastic increase in the amount of heat being absorbed and stored by ocean waters during the last 60 years. The study, by authors at Rutgers University, Columbia University's Lamont-Doherty Earth Observatory, and Woods Hole Oceanographic Insitution, reconstructs the history of temperatures in the western Pacific roughly 500-900 meters down through chemical analysis of shells from a species of single-celled organisms called foraminifers (or "forams").

The ratio of magnesium to calcium in the particular foram selected for study and found in ocean sediment cores, Hyalinea balthica, is a precise indicator of ambient temperature at the time the organism lived and died--a standard technique in paleoclimatology.

The three researchers found that the prevailing trend through most of the 10 000 year period was toward cooler temperatures. The cooling rate increased markedly during what's called the Little Ice Age of the European late Middle Ages, only to stop and reverse around the year 1600. After that the rate of Pacific warming was very gradual until about 60 years ago, when it leaped by a factor of 15. "Over a long time, the ocean's interior acts like a capacitor and builds up large (positive and negative) heat anomalies that reflect and, more importantly, affect the global climate," the article says.

There have been times in the ocean records that the three researchers compiled when water temperatures have been considerably higher than they are today, let it be said. The researchers emphasize the rate at which heat can be absorbed or ejected, and the big increase in the uptake rate during recent decades. “We may have underestimated the efficiency of the oceans as a storehouse for heat and energy,” commented Yair Rosenthal of Rutgers, the principal author of the study. “It [that heat storage] may buy us some time—how much time, I don't really know—to come to terms with climate change. But it's not going to stop climate change.”

The thinking is that storage of heat from a warming atmosphere represents a kind of lurking, growing monster that eventually will surface and return to the atmosphere.

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