Increasing seasonal upwelling in the subtropical South Atlantic over the past 700,000 yrs: Evidence from deep-living planktonic foraminifera

1992 ◽  
Vol 19 (1-2) ◽  
pp. 1-12 ◽  
Author(s):  
G.P. Lohmann
2011 ◽  
Vol 7 (4) ◽  
pp. 1337-1349 ◽  
Author(s):  
G. M. Ganssen ◽  
F. J. C. Peeters ◽  
B. Metcalfe ◽  
P. Anand ◽  
S. J. A. Jung ◽  
...  

Abstract. The oxygen isotopic composition of planktonic foraminifera tests is one of the widest used geochemical tools to reconstruct past changes of physical parameters of the upper ocean. It is common practice to analyze multiple individuals from a mono-specific population and assume that the outcome reflects a mean value of the environmental conditions during calcification of the analyzed individuals. Here we present the oxygen isotope composition of individual specimens of the surface-dwelling species Globigerinoides ruber and Globigerina bulloides from sediment cores in the Western Arabian Sea off Somalia, inferred as indicators of past seasonal ranges in temperature. Combining the δ18O measurements of individual specimens to obtain temperature ranges with Mg/Ca based mean calcification temperatures allows us to reconstruct temperature extrema. Our results indicate that over the past 20 kyr the seasonal temperature range has fluctuated from its present value of 16 °C to mean values of 13 °C and 11 °C for the Holocene and LGM, respectively. The data for the LGM suggest that the maximum temperature was lower, whilst minimum temperature remained approximately constant. The rather minor variability in lowest summer temperatures during the LGM suggests roughly constant summer monsoon intensity, while upwelling-induced productivity was lowered.


1999 ◽  
Vol 63 (2) ◽  
pp. 503
Author(s):  
Stephen Badsey ◽  
Daniel K. Gibran

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Ilana Wainer ◽  
Luciana Figueiredo Prado ◽  
Myriam Khodri ◽  
Bette Otto-Bliesner

1973 ◽  
Vol 3 (1) ◽  
pp. 110-116 ◽  
Author(s):  
Constance Sancetta ◽  
John Imbrie ◽  
N.G. Kipp

AbstractQuantitative paleo-environmental analyses of planktonic foraminifera in 182 samples covering the past 130,000 years in North Atlantic deep-sea core V23-82 yield time series interpreted in terms of changing surface-water conditions. An absolute chronology is estimated by linear interpolation between levels dated by 14C or by stratigraphic correlation with other radiometrically dated climatic records. Significant events include: (1) rapid warming at 127,000 YBP, marking the start of the penultimate North Atlantic and European interglacial; (2) 124,000 YBP temperature maximum (Eemian); (3) 109,000 YBP cooling, correlated with the beginning of the last European glaciation (Würm), and representing a temporary cooling of the North Atlantic; (4) severe cooling 73,000 YBP, marking the start of the last full glacial regime in the North Atlantic; (5) short warm intervals within the last glacial regime dated at 59,000 YBP, 48,000 YBP, and 31,000 YBP; (6) rapid termination of the last glacial interval at 11,000 YBP; (7) a 6000 YBP hypsi-saline, followed by lowering salinity values presumably associated with decreasing flux of Gulf Stream waters over the core site.


I am sure that the greatest honour that can befall an after-dinner speaker is to propose the toast to the Royal Society and I simply couldn’t imagine why the Royal Society chose a mere Admiral to propose the toast. Then I got hold o f their history and I found out how much they depended on Admirals in the past. In the last two hundred years, forty-six o f the most distinguished Fellows of the Royal Society have been Admirals. The only Fellow of the Royal Society about whom a film has been made twice, was in fact a young Captain who also became an Admiral and a Fellow of the Royal Society. One was made before the war and there’s one in London now; you can see it in glorious technicolour and cinemascope. It’s about a man called William Bligh who had some trouble on the Bounty. But it wasn’t only Admirals who became Fellows of the Royal Society, because in those days there were also Captains. Edmund Halley, Astronomer Royal, commanded one of His Majesty’s Ships in 1698, with orders to traverse the North and South Atlantic Oceans in order to survey compass directions.


2016 ◽  
Vol 31 (10) ◽  
pp. 1302-1314 ◽  
Author(s):  
Jacob N. W. Howe ◽  
Alexander M. Piotrowski ◽  
Delia W. Oppo ◽  
Kuo-Fang Huang ◽  
Stefan Mulitza ◽  
...  

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