Mid-latitude interhemispheric hydrologic seesaw over the past 550,000 years

Abstract

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.

Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw

“…As part of the upward limb of the Hadley Cells, the ITCZ plays a crucial role in global energy redistribution. Temperature-driven meridional displacement of the tropical Hadley Cells and the ITCZ45 induced synchronous shifts in higher latitude climate patterns1 on millennial timescales. High signal-to-noise ratios of millennial-scale climate shifts during glacial periods, largely due to different boundary conditions related to the presence of extensive continental ice sheets, facilitate their detection in proxy records.…”

“…Hemispheric antiphasing of large-scale precipitation patterns in low- and mid-latitude regions, driven by the seasonal migration of the Intertropical Convergence Zone (ITCZ), has been described over orbital timescales, Dansgaard-Oeschger (DO), and Heinrich events123. As part of the upward limb of the Hadley Cells, the ITCZ plays a crucial role in global energy redistribution.…”

“…Although this atmospheric reorganization has been described over glacial-interglacial timescales, the dynamics and latitudinal extent of this interhemispheric hydrologic seesaw1 over the most recent past are still poorly understood. Additionally, chronological uncertainties, although less significant than in Pleistocene reconstructions, and low signal-to-noise ratios in Holocene paleoclimate records can hinder interpretations of rapid climate change, and this is particularly true over the last few millennia.…”

Global-scale remote sensing of water isotopologues in the troposphere: representation of first-order isotope effects

“…1d-f and 2c-e). This area of very high sea surface temperature (SST), persistent strong convection and rainfall, and more depleted vapor extends over the inner tropics and is surrounded by a zone of descending air, less rainfall (Oort and Yienger, 1996;Jo et al, 2014), and more enriched vapor. We consider this pattern as a manifestation of the isotopic amount effect since the isotopic pattern anti-correlates with regional rainfall (Brown et al, 2008;Dansgaard, 1964;Kurita et al, 2011;Lee and Fung , 2007;Lee et al, 2011;Risi et al, 2008;Worden et al, 2007).…”

Reconstruction of the Northeast Asian monsoon climate history for the past 400 years based on textural, carbon and oxygen isotope record of a stalagmite from Yongcheon lava tube cave, Jeju Island, Korea

“…Carbon isotope compositions of speleothems are also known to be controlled by type of vegetation, biological activities, surface environment, and use and karstification (McDermott, 2004;Cosford et al, 2009). Recent studies showed that carbon isotope compositions of stalagmites also indicate East Asian summer monsoon intensity variations (Jo et al, 2010b(Jo et al, , 2014.…”