Mean growing season soil PCO, data were obtained for 19 regions of the woi.1 in nine countries. Bivariate anL multiple linear regression analysis with soil log(PC0,) as the dependent variable and TEMP, PRECIP, log (AET), and log(PET) as the four climatic independent variables demonstrated that AET was the best independent predictor of soil PCO, .An improved soil PC0,-AET model was developed by assuming (1) that as AET approaches zero, soil PCO, approaches the atmospheric value and (2) that there is an upper limit to soil PCO, at very high AET. This model has the form log(PC0,) = -3.47 + 2.09 (1 -e-0'00172 AET) where AET is in mm. It explains 67 per cent of the initial variation in the soil PCO, data, predicts a soil log(PC0,) of -3.47 at AET = 0, and an upper limit of 3.5 per cent (log(PC0,) = -1.45) for mean growing season soil PCO, at AET values of 2000mm and above. The results of this study suggest that soil PCO, levels in tropical areas are, on average, higher than those in temperate, alpine, and arctic regions.

No abstract

No abstract

No abstract

Two stalagmites from Anjohibe Cave have annual layers made up of inclusion-rich calcite over inclusion-free calcite or of darker aragonite over clear aragonite. Geochemical evidence indicates that the basal units are deposited slowly in the wet season and the upper units more rapidly in the dry season. For the period with rainfall and temperature data (ad 1951–1992), layer thickness correlates well with the Southern Oscillation Index (SOI), as well as rainfall, water surplus, and actual evapotranspiration (AET) at nearby Majunga. Com parison of the layer record for one stalagmite with 1866–1994 SOI data indicates that layer thickness correlates best with the frequency and intensity of warm, low-phase SO (El Niño) events, not with average SOI conditions. In addition, the 415-year layer thickness time-series from that speleothem agrees remarkably well with historical records of El Niño frequency, with Galápagos (Ecuador) coral records of sea-surface temperature in the eastern Pacific, and with accumulation rates on the Quelccaya Ice Cap of Peru, which are lower at times of high El Niño frequency.

Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2 ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26 m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2 ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism.

No abstract

No abstract