What was done
The authors analyzed magnetic susceptibility (related to summer monsoon intensity), organic matter (related to vegetation coverage and biomass), and granularity (related to wind speed) associated with samples of "six aeolian sand layers overlapping six sandy paleosol layers" that comprise "an uninterrupted and whole stratigraphic profile, the Xilinhot profile," of the Hunshandake Desert in the eastern part of Inner Mongolia.

What was learned
Jin et al. report that their power spectrum analysis of magnetic susceptibility revealed two periodicities, one of which has a value of 1465 years that "approximates to the 1450-year period of the North Atlantic Ice floating event and to the arid-humid cycle of 1450-1470 years in Arabia (Pinegina et al., 2003; Sirocko et al., 1996)."

With respect to the most recent 1800-year segment of this pervasive oscillation, they say that "cold events occurred in many regions of China during 240-800 AD (Yang et al., 2002), and even a cold climate event during 1.8-1.4 kaBP had been recorded in the south deep sea of Iceland (Bianchi and McCave, 1999), besides another ice-floating event appeared in [the] North Atlantic at 1.4 kaBP (Bond et al., 1997)."  These several events, of course, were all part of the globe-girdling Dark Ages Cold Period.

Subsequently, Jin et al. report that a "warming event happened in Daihai Lake in the southern part of the study region during 1.2-0.9 kaBP (Jin et al., 2002), and most of the China region had warming event records during 800-1400 AD (Yang et al., 2002), even the track records had been discovered all over the world (Bianchi and McCave, 1999; Stuiver et al., 1997; Cronin et al., 2003), which indicated that this was the Medieval Warm Period."

During the period AD 1300-1800, Jin et al. say their data recorded the last cold event of their study, and that "more records of this cold event had been discovered in China and even in other parts of the world (Bond et al., 1997; Yang et al., 2002; Bianchi and McCave, 1999; Cronin et al., 2003; Wang et al., 1998)."  In addition, they state that "the extreme of this cold event took place at about 400 aBP, corresponding to the Little Ice Age cold event."

Last of all, the six Chinese scientists note that "the arid events of the study area coincided with the cold events in North Atlantic and arid events in middle to low latitudinal zones, which indicated that the periodical change of Holocene climate in Hunshandake Desert has global significance."

What it means
Evidence continues to pile upon evidence for the reality of a global millennial-scale oscillation of climate that is totally independent of, and totally unforced by, changes in atmospheric CO2 concentration.  Hence, there is every reason to believe that the most recent warming portion of this cycle, which led to the demise of the Little Ice Age and the birth of the Modern Warm Period, was a natural phenomenon and not the result of the coincidental increase in the air's CO2 content produced by anthropogenic CO2 emissions.

References
Bianchi, G.G. and McCave, I.N.  1999.  Holocene periodicity in North Atlantic climate and deep-ocean flow south of Iceland.  Nature 397: 515-517.

Bond, G., Showers, W., Chezebiet, M., Lotti, R., Almasi, P., deMenocal, P., Priore, P., Cullen, H., Hajdas, I. and Bonani, G.  1997.  A pervasive millennial scale cycle in North-Atlantic Holocene and glacial climates.  Science 278: 1257-1266.

Cronin, T.M., Dwyer, G.S., Kamiya, T. et al.  2003.  Medieval warm period, little ice age and 20th century temperature variability from Chesapeake Bay.  Global and Planetary Change 36: 17-29.

Jin, Z.D., Shen, J. and Wang, S.M.  2002.  The medieval warm period in the Daihai area.  Journal of Lake Science 14: 209-216.

Pinegina, T.K., Bourgeois, J., Bazanova, L.I. et al.  2003.  A millennial-scale record of Holocene tsunamis on the Kronotskiy bay coast, Kamchatka, Russia.  Quaternary Research 59: 36-47.

Sirocko, F., Garbe-Schonberg, D., McIntyre, A. et al.  1996.  Teleconnections between the subtropical monsoon and high-latitude climates during the last deglaciation.  Science 272: 526-529.

Stuiver, M., Braziunas, T.F. and Grootes, P.M.  1997.  Is there evidence for solar forcing of climate in the GISP2 oxygen isotope record?  Quaternary Research 48: 259-266.

Wang, S.W., Ye, J.L. and Gong, D.Y.  1998.  Climate in China during little ice age.  Quaternary Research 18: 54-64.

Yang, B., Braeuning, A., Johnson, K.R. and Yafeng, S.  2002.  General characteristics of temperature variation in China during the last two millennia.  Geophysical Research Letters 29: 381-384.