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The twentieth century was the wettest period in northern Pakistan over the past millennium


Twentieth-century warming could lead to increases in the moisture-holding capacity of the atmosphere, altering the hydrological cycle and the characteristics of precipitation1. Such changes in the global rate and distribution of precipitation may have a greater direct effect on human well-being and ecosystem dynamics than changes in temperature itself2,3. Despite the co-variability of both of these climate variables3, attention in long-term climate reconstruction has mainly concentrated on temperature changes4,5,6,7,8. Here we present an annually resolved oxygen isotope record from tree-rings, providing a millennial-scale reconstruction of precipitation variability in the high mountains of northern Pakistan. The climatic signal originates mainly from winter precipitation, and is robust over ecologically different sites. Centennial-scale variations reveal dry conditions at the beginning of the past millennium and through the eighteenth and early nineteenth centuries, with precipitation increasing during the late nineteenth and the twentieth centuries to yield the wettest conditions of the past 1,000 years. Comparison with other long-term precipitation reconstructions indicates a large-scale intensification of the hydrological cycle coincident with the onset of industrialization and global warming, and the unprecedented amplitude argues for a human role.

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We are grateful to K. Briffa, E. Cook, E. Hendy, R. Wilson, M. Gagen, J. Waterhouse, M. Gumpert and U. Büntgen for comments and suggestions. We thank S. Andres, B. Kammer, W. Laumer, G. Reiss, M. Schrimpf and C. Welscher for laboratory assistance, and C. Welscher, M. Gumpert and A. Shafgat for logistical support in the field. This research was funded by the German Federal Ministry for Education and Research, the German Science Foundation Schl 3-1, the European Union (ALPIMP and ISONET) and the Swiss National Science Foundation (NCCR-Climate).

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Correspondence to Kerstin S. Treydte.

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This file contains Supplementary Tables 1 and 2, Supplementary Figures and accompanying Legends, Supplementary Notes and additional references. (PDF 2998 kb)

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Figure 1: Site locations and Central Asian average precipitation distribution 9 in January and July.
Figure 2: δ 18 O site chronologies and climate correlation.
Figure 3: δ 18 O-derived precipitation reconstruction for northern Pakistan.
Figure 4: Precipitation reconstruction for northern Pakistan and long-term precipitation variations for different regions in the northern hemisphere.


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