The peatland/ice age hypothesis revised, adding a possible glacial pulse trigger

Abstract

Carbon sequestering in peatlands is believed to be a major climate‐regulating mechanism throughout the late Phanerozoic. Since plant life first evolved on land, peatlands have been significant carbon sinks, which could explain significant parts of the large variations in atmospheric carbon dioxide observed in various records. The result is peat in different degrees of metamorphosis, i.e. lignite, hard coal and graphite. During phases of extensive glaciations such as the 330–240 Ma Pangea Ice Age, atmospheric carbon dioxide was critically low. This pattern repeats itself during the Pleistocene when carbon dioxide oscillates with an amplitude of c. 200–300 ppmv. This paper suggests that the ice age cycles during the Pleistocene are generated by the interglacial growth of peatlands and the subsequent sequestering of carbon into this terrestrial pool. The final initiation of ice age pulses towards the end of inter‐glacials, on the other hand, is attributed to the cyclic influx of cosmic dust to the Earth surface, which in turn regulates cloud formation and the incoming shortwave radiation. These shorter cycles have a frequency of c. 1000‐1250 years and might be connected to sunspot or other low frequency solar variations. In a wider context the ice age cycling could be regarded as an interplay between terrestrial life on the high latitudes of the northern hemisphere and the marine subsurface life in the southeast. If the results presented here are correct, the present global warming might just be the early part of a new warm period such as the Bronze Age and the Roman and Medieval Warm periods. This could be caused by entry into another phase of decreasing influx rates of cosmic dust. The increasing concentrations of atmospheric carbon dioxide might have contributed to this warming but, most important of all, it might temporarily have saved us from a new ice age pulse.

The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact

“…Microspherules from the rooftop sample lacked Ti. Franzén and Cropp (13), in their discussion of microspherules from Scandinavian peat bogs, describe criteria for distinguishing terrestrial from ET sources based upon proportions of rare-earth elements. In our samples, europium (Eu) is depleted with respect to gadolinium (Gd) and samarium (Sm), suggesting that most of the Murray Springs magnetic particles are derived from continental rocks rather than meteoritic material (Table 2).…”

Accumulation of impact markers in desert wetlands and implications for the Younger Dryas impact hypothesis

“…Those that survive do so as either intact meteorites or are ablated along the way and eventually settle to the ground as micrometeorites or dust, which can include spherules. Magnetic spherules have been documented in a wide range of depositional settings, including Arctic and Antarctic ice (34,35), deep-sea sediments (36), lake sediments (37), alluvial sediment (38), and peat bogs (39,40), and have even been collected directly from the atmosphere (41). Thus, some of the magnetic spherules present in our samples may have a cosmic origin.…”

Implications from chemical, structural and mineralogical studies of magnetic microspherules from around the lower younger dryas boundary (new mexico, usa)

“…The REEs are about 300 times more common in terrestrial materials than in meteorites (e.g. Anders and Grevesse 1989;Wedepohl 1995;Franzén and Cropp 2007). The REE composition of the BWD-1 hollow microspherules is distinct from either that of detrital magnetite and ilmenite or of the host sediments (Fig.…”

“…; Gál‐Sólymos and Don ; Stankowski et al . ; Franzen and Cropp ; van Ginneken et al . ; Misawa et al .…”