A major (but little noted) divergence of opinion has developed among climate scientists over the orbital-scale periodicity and phasing of tropical monsoon variations. Kutzbach (1981. Monsoon climate of the early Holocene: climate experiment with Earth's orbital parameters for 9000 years ago. Science 214, 59-6 1) proposed that monsoons are driven by northern summer insolation at the precession period, but Clemens and Prell (1990. Late Pleistocene variability of Arabian Sea Summer monsoon winds and continental aridity: eolian records from the lithogenic component of deep-sea sediments. Paleoceanography 5, 109-145; 2003. A 350,000-year summer-monsoon multi-proxy stack from the Owen Ridge, Northern Arabian Sea. Marine Geology 201, 35-51) inferred a more complicated response tied to latent heat transfer from the Southern Hemisphere. Because tropical monsoons affect climate over a vast area, resolving this divergence is an important task for the climate Community. The purpose of this note is to highlight definitive evidence from high-resolution dating of speleothem calcite that provides unambiguous support for the Kutzbach hypothesis. (C) 2006 Elsevier Ltd. All rights reserved.