Mid-latitude interhemispheric hydrologic seesaw over the past 550,000 years.
An interhemispheric hydrologic seesaw--in which latitudinal migrations of the Intertropical Convergence Zone (ITCZ) produce simultaneous wetting (increased precipitation) in one hemisphere and drying in the other--has been discovered in some tropical and subtropical regions. For instance, Chinese and Brazilian subtropical speleothem (cave formations such as stalactites and stalagmites) records show opposite trends in time series of oxygen isotopes (a proxy for precipitation variability) at millennial to orbital timescales, suggesting that hydrologic cycles were antiphased in the northerly versus southerly subtropics. This tropical to subtropical hydrologic phenomenon is likely to be an initial and important climatic response to orbital forcing. The impacts of such an interhemispheric hydrologic seesaw on higher-latitude regions and the global climate system, however, are unknown. Here we show that the antiphasing seen in the tropical records is also present in both hemispheres of the mid-latitude western Pacific Ocean. Our results are based on a new 550,000-year record of the growth frequency of speleothems from the Korean peninsula, which we compare to Southern Hemisphere equivalents. The Korean data are discontinuous and derived from 24 separate speleothems, but still allow the identification of periods of peak speleothem growth and, thus, precipitation. The clear hemispheric antiphasing indicates that the sphere of influence of the interhemispheric hydrologic seesaw over the past 550,000 years extended at least to the mid-latitudes, such as northeast Asia, and that orbital-timescale ITCZ shifts can have serious effects on temperate climate systems. Furthermore, our result implies that insolation-driven ITCZ dynamics may provoke water vapour and vegetation feedbacks in northern mid-latitude regions and could have regulated global climate conditions throughout the late Quaternary ice age cycles.
Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, South Korea.
Kyoung-nam
KN
Jo
Department of Geology, Kangwon National University, Gangwondo 200-701, South Korea.
Kyung Sik
KS
Woo
Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, South Korea.
Sangheon
S
Yi
Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, South Korea.
Dong Yoon
DY
Yang
Department of Geological Sciences, Pusan National University, Busan 609-735, South Korea.
Hyoun Soo
HS
Lim
College of Geography Science, Nanjing Normal University, Nanjing 210097, China.
Yongjin
Y
Wang
1] Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China [2] Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Hai
H
Cheng
Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA.
R Lawrence
RL
Edwards
D002980:Climate; D049690:History, Ancient; D062070:Hydrology; D046448:Ice Cover; D007723:Korea; D010140:Pacific Ocean; D011891:Rain; D013997:Time Factors; D014329:Tropical Climate