Stabilization of dense Antarctic water supply to the Atlantic Ocean overturning circulation

The lower limb of the Atlantic overturning circulation is resupplied by the sinking of dense Antarctic Bottom Water (AABW) that forms via intense air–sea–ice interactions next to Antarctica, especially in the Weddell Sea. In the last three decades, AABW has warmed, freshened and declined in volume across the Atlantic Ocean and elsewhere, suggesting an ongoing major reorganization of oceanic overturning. However, the future contributions of AABW to the Atlantic overturning circulation are unclear. Here, using observations of AABW in the Scotia Sea, the most direct pathway from the Weddell Sea to the Atlantic Ocean, we show a recent cessation in the decline of the AABW supply to the Atlantic overturning circulation. The strongest decline was observed in the volume of the densest layers in the AABW throughflow from the early 1990s to 2014; since then, it has stabilized and partially recovered. We link these changes to variability in the densest classes of abyssal waters upstream. Our findings indicate that the previously observed decline in the supply of dense water to the Atlantic Ocean abyss may be stabilizing or reversing and thus call for a reassessment of Antarctic influences on overturning circulation, sea level, planetary-scale heat distribution and global climate

Fecal bile acid concentration in distance runners

Fecal bile acid concentration, fecal characteristics, bowel habits and habitual food intake were measured in male distance runners (n = 14) and sedentary men (n = 14). Fecal bile acid concentration was significantly (p less than 0.05) lower and stool weight, frequency of defecation and daily intake of fibre, carbohydrate, and protein were significantly (p less than 0.01) higher in the runners. After adjustment for differences in dietary fibre intake, fecal bile acid concentration was no longer significantly different between the distance runners and the sedentary men, but frequency of defecation remained significantly (p less than 0.05) higher in the runners. This study has identified lower fecal bile acid concentration in distance runners, which was probably due mainly to dilution of colon contents by higher consumption of dietary fibre. These findings may be relevant to the reduced incidence of colon cancer in physically active subjects