Buried Peat Layers in a Japanese Subalpine Snowpatch Grassland
Daimaru, H., Ohtani, Y., Ikeda, S., Okamoto, T. and Kajimoto, T. 2002. Paleoclimatic implication of buried peat layers in a subalpine snowpatch grassland on Mt. Zarumori, northern Japan. Catena 48: 53-65.
Working in a snowpatch grassland within a shallow depression of landslide origin on the southeastern slope of Japan's Mt. Zarumori (~39.8°N, 140.8°E), Daimaru et al. dug 27 soil pits at various locations in and around the central location of the snowpatch, carefully examining what they found and determining its age based on 14C dating and tephrochronology.
The five researchers report that "peaty topsoils were recognized at seven soil pits in the dense grassland, whereas sparse grassland lacked peaty topsoil," and they say that "most of the buried peat layers contained a white pumice layer named 'To-a' that fell in AD 915." This observation, plus their 14C dating, led them to conclude that the buried peat layers in the poor vegetation area indicate "warming in the melt season," as well as "a possible weakened winter monsoon in the Medieval Warm Period," which their data suggest prevailed at the site they studied throughout the tenth century, i.e., AD 900-1000. And the fact that they write that "many studies have reported climatic signals that are correlated with the Medieval Warm Period from the 9th to 15th centuries in Japan," suggests that the possibly weakened winter monsoon of AD 900-1000 may also have been a consequence of the warmer temperatures of that period.
The evidence continues to mount for a global Medieval Warm Period that was warmer than the Current Warm Period has been to date. And since the atmosphere's CO2 concentration was so much lower a millennium ago than it is today, there is no compelling reason to attribute the lesser warmth of the present to the air's higher CO2 content.
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