![]() ![]() "Our study has established a benchmark of radiocarbon measurements of the major ocean basins, and having compiled and analyzed that data, we can confidently say that changing overturning circulation in the Pacific is consistent with the ocean being a significant driver of lower greenhouse gases during the last ice age." "It's intuitive to think that the Pacific would play a major role in climate regulation during the last glacial period-it's huge, double the volume of the Atlantic-but we didn't have a lot of data to say that previously," said lead author Patrick Rafter, UCI assistant researcher in Earth system science. They uncovered this transposition by analyzing traces of carbon-14, or radiocarbon, in thousands of fossil sediment samples from around the world, some dating back as far as 25,000 years. In a paper published in Science Advances, the researchers suggest that this shift in the 3D churning of such a large ocean basin must have enhanced the sequestration of CO 2 in the deep sea, thereby lowering the amount of the greenhouse gas in ice-age Earth's atmosphere. The overturning circulation of the Pacific Ocean "flipped" during the last ice age, altering the placement of ancient waters rich in carbon dioxide, according to Earth system scientists at the University of California, Irvine. The dashed line in (B) is 1:1, the solid line is the slope, and the red envelope is 68 and 95% error range. The basin colors in (A) identify the location of measurements in ( B), which compares preindustrial seawater dissolved inorganic carbon (DIC) from and all compiled proxy 14C/C (differenced from the contemporaneous atmosphere) over the past 4 ka (see fig. Diamonds are sites with new data provided in this study. Closed symbols are γ n > 28.0 kg m −3 “bottom water” sites. Open symbols are mid-depth sites above or on the neutral density surface γ n = 28.0 kg m −3. An ensemble of marine fossil 14C/C and a first-order test of fidelity.( A) Locations for all deep-sea proxy seawater 14C/C measurements used in this study, all of which are below the neutral density surface (γ n) = 27.5 kg m −3 (below the depth of intermediate water masses). ![]()
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