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Millennial Cycling of Climate in Northeast Japan
Yamada, K., Kamite, M., Saito-Kato, M., Okuno, M., Shinozuka, Y. and Yasuda, Y. 2010. Late Holocene monsoonal-climate change inferred from Lakes Ni-no-Megata and San-no-Megata, northeastern Japan. Quaternary International 220: 122-132.

What was done
Working with sediment cores they obtained in July of 2007 from Lakes Ni-no-Megata (39°57'N, 139°43'E) and San-no-Megata (39°56'N, 139°42'E) on the Oga Peninsula of northeastern Japan, the authors measured a number of sediment properties, among which were sulfur content and coarse mineral grains, the former of which served as a proxy for paleo-Asian summer monsoon activity and the latter of which served as a proxy for paleo-Asian winter monsoon activity over the last two millennia.

What was learned
Yamada et al.'s data revealed the presence of a cold/dry interval stretching from AD 1 to 750, a warm/humid interval stretching from AD 750 to 1200, and another cold/dry interval stretching from AD 1200 to the present; and they say that these intervals could represent, respectively, "the Dark Ages Cold Period (DACP), the Medieval Warm Period (MWP) and the Little Ice Age (LIA)." In further discussing their findings, they note that they complement the findings of Kitagawa and Matsumoto (1995), whose study of tree-ring records in southern Japan "suggested the existence of one warm interval at AD 750-1300 and two cold intervals at AD 200-750 and AD 1600-1800," as well as the findings of Sakaguchi (1983), whose study of the pollen record of peaty sediments in central Japan revealed "an unusual warm interval (AD 700-1300) and a cool interval (ca. AD 250-700)." In addition, they write that the "strong summer monsoon and weak winter monsoon at Lakes Ni-no-Megata and San-no-Megata from AD 750-1200 correlates with the lower δ18O values from Wangxiang Cave (Zhang et al., 2008) and lower values of minerogenic clastic content (Chu et al., 2009)."

What it means
Once again, we find more evidence for the global scope of the millennial-scale oscillation of climate that reverberates throughout glacial and interglacial periods alike. See, for example, the many items archived under the heading of Climate Oscillations (Millennial Variability) in our Subject Index. And we also accumulate ever more evidence for the global scope of the Medieval Warm Period -- see our Medieval Warm Period Project -- which was actually warmer than the Current Warm Period has been to data in many parts of the world, and at a time when the atmosphere's CO2 concentration was a good 100 ppm less than it is today.

Chu, G., Sun, Q., Gu, Z., Rioual, P., Liu, Q., Wang, K., Han, J. and Liu, J. 2009. Dust records from varved lacustrine sediments of two neighboring lakes in northeastern China over the last 1400 years. Quaternary International 194: 108-118.

Kitagawa, H. and Matsumoto, E. 1995. Climate implications of δ13C variations in a Japanese ceder (Cryptomeria japonica) during the last two millennia. Geophysical Research Letters 22: 2155-2158.

Sakaguchi, Y. 1983. Warm and cold stages in the past 7600 years in Japan and their global sea level changes and the ancient Japanese history. Bulletin of Department of Geography, University of Tokyo 15: 1-31.

Zhang, P.Z., Cheng, H., Edwards, R.L., Chen, F.H., Wang, Y.J., Yang, X.L., Liu, J., Tan, M., Wang, X.F., Liu, J.H., An, C.L., Dia, Z.B., Zhou, J., Zhang, D.Z., Jia, J.H., Jin, L.Y. and Johnson, K.R. 2008. A test of climate, sun, and culture relationships from an 1810-year Chinese cave record. Science 322: 940-942.

Reviewed 24 November 2010