Major Δ14C excursions during the late glacial and early Holocene: changes in ocean ventilation or solar forcing of climate change?

The atmospheric 14C record during the Late Glacial and the early Holocene shows sharp increases simultaneous with cold climatic phases. These increases in the atmospheric 14C content are usually explained as the effect of reduced oceanic CO2 ventilation after episodic outbursts of large meltwater reservoirs into the North Atlantic. In this hypothesis the stagnation of the thermohaline circulation is the cause of both climate change as well as an increase in atmospheric 14C: As an alternative hypothesis we propose that changes in 14C production give an indication for the cause of the recorded climate shifts: changes in solar activity cause fluctuations in the solar wind, which modulate the cosmic ray intensity and related 14C production. Two possible mechanisms amplifying the changes in solar activity may result in climate change. In the case of a temporary decline in solar activity: (1) reduced solar UV intensity may cause a decline of stratospheric ozone production and cooling as a result of less absorption of sunlight. This might influence atmospheric circulation patterns (extension of Polar Cells and equatorward relocation of mid-latitude storm tracks), with effects on oceanic circulation, and (2) increased cosmic ray intensity may stimulate cloud formation and precipitation, while 14C production increases.

Arctic fox (Alopex lagopus) from the North Sea

The first record of arctic fox Alopex lagopus (Linnaeus, 1758) from the Eurogeul area (North Sea) is reported based on a distal humerus fragment collected by private collectors from dredged sediments on ‘De Zandmotor’. It was radiocarbon dated to 29,900 + 550/- 490 BP (GrA-69520), which is younger than most Late Pleistocene fossils from this area. Besides adding a new species to the faunal list of the Eurogeul area, this specimen also demonstrates the value of beaches nourished with dredged sediments and highlights the importance of close cooperation between all parties interested in palaeontology: from collector to researcher. The discovery prompted re-examination of the other arctic fox specimen from the North Sea, a femur of which the identification is here confirmed and measurements are provided