Feeling the Pressure

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Science  04 Jan 2013:
Vol. 339, Issue 6115, pp. 11
DOI: 10.1126/science.339.6115.11-c

Volcanism has a substantial impact on climate, the global carbon cycle, the evolution of land-forms, and a host of other important processes; establishing how it has varied in the past is thus a key to understanding those topics. It is also known that volcanic activity can be influenced by surface mass loading and the resulting isostatic adjustment of the underlying Earth and that glacial cycles change the distribution of water and ice on the crust. Therefore, the possibility that volcanism might vary in accordance with Milankovich periodicities (changes in the amount and distribution of solar energy incident on Earth due to variations in its orbital configuration) in response to glacial cycling has been an intriguing one. Kutterolf et al. present the most comprehensive data set yet to address this idea, developed from an extensive collection of marine sediment cores from around the Pacific Ocean basin. From these cores, they were able to show that the frequency of circum-Pacific volcanism varied with a 41,000-year period, the obliquity band of Milankovich cycles, and that changes in volcanic activity lagged slightly behind glacial unloading, consistent with the idea that eruptions are forced by the mass distribution variations attendant with deglaciations.

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