Large deglacial shifts of the Pacific Intertropical Convergence Zone

A W Jacobel,G Winckler,R F Anderson,J F Mcmanus

doi:10.1038/ncomms10449

A W Jacobel, G Winckler + Show 2 more

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https://doi.org/10.1038/ncomms10449

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Abstract

The position of the Intertropical Convergence Zone (ITCZ) is sensitive to changes in the balance of heat between the hemispheres which has fundamental implications for tropical hydrology and atmospheric circulation. Although the ITCZ is thought to experience the largest shifts in position during deglacial stadial events, the magnitude of shifts has proven difficult to reconstruct, in part because of a paucity of high-resolution records, particularly those including spatial components. Here we track the position of the ITCZ from 150 to 110 ka at three sites in the central equatorial Pacific at sub-millennial time resolution. Our results provide evidence of large, abrupt changes in tropical climate during the penultimate deglaciation, coincident with North Atlantic Heinrich Stadial 11 (∼136–129 ka). We identify this event both as a Northern Hemisphere increase in aeolian dust and as a shift in the mean position of the ITCZ a minimum of 4° southwards at 160° W.

Highlights

The position of the Intertropical Convergence Zone (ITCZ) is sensitive to changes in the balance of heat between the hemispheres which has fundamental implications for tropical hydrology and atmospheric circulation
Understanding the forcings and dynamics behind these atmospheric shifts is important for predicting future changes in the ITCZ/monsoon complex with significant implications for communities living in hydrologically sensitive environments[9]
Few dust flux records exist from the central equatorial Pacific, but a low-resolution record from TT013-72PC (72PC) at 0.1° N, 139.4° W provides an important comparison for our sediment cores

Summary

Introduction

The position of the Intertropical Convergence Zone (ITCZ) is sensitive to changes in the balance of heat between the hemispheres which has fundamental implications for tropical hydrology and atmospheric circulation. Our results provide evidence of large, abrupt changes in tropical climate during the penultimate deglaciation, coincident with North Atlantic Heinrich Stadial 11 (B136–129 ka) We identify this event both as a Northern Hemisphere increase in aeolian dust and as a shift in the mean position of the ITCZ a minimum of 4° southwards at 160° W. The Intertropical Convergence Zone (ITCZ) is a band of vigorous atmospheric convection and precipitation that varies position seasonally in connection with the latitude of maximum local insolation and on longer timescales in response to changes in the thermal equator[1,2] This sensitivity has been reproduced in model experiments[3,4] and is indicated by a variety of palaeoclimate reconstructions covering the Last Glacial Maximum, last deglaciation and Holocene[5,6,7]. Our data reconstruct a large, abrupt change in tropical Pacific climate over TII, characterized by both an increase in atmospheric dust abundance and by a shift of the ITCZ of at least 4° southwards

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