International Journal of Mass Spectrometry 228 (2003) 1–33 Review Stable isotope ratio mass spectrometry in global climate change research Prosenjit Ghosh, Willi A. Brand ∗ Isotopen- und Gaslabor, Max-Planck-Institut für Biogeochemie, Postfach 100164, Jena 07701, Germany Received 29 January 2003; accepted 20 May 2003 Abstract Stable isotope ratios of the life science elements carbon, hydrogen, oxygen and nitrogen vary slightly, but significantly in major compartments of the earth. Owing mainly to antropogenic activities including land use change and fossil fuel burning, the 13 C/ 12 C ratio of CO 2 in the atmosphere has changed over the last 200 years by 1.5 parts per thousand (from about 0.0111073 to 0.0110906). In between interglacial warm periods and glacial maxima, the 18 O/ 16 O ratio of precipitation in Greenland has changed by as much as 5 parts per thousand (0.001935–0.001925). While seeming small, such changes are detectable reliably with specialised mass spectrometric techniques. The small changes reflect natural fractionation processes that have left their signature in natural archives. These enable us to investigate the climate of past times in order to understand how the Earth’s climatic system works and how it can react to external forcing. In addition, studying contemporary isotopic change of natural compartments can help to identify sources and sinks for atmospheric trace gases provided the respective isotopic signatures are large enough for measurement and have not been obscured by unknown processes. This information is vital within the framework of the Kyoto process for controlling CO 2 emissions. © 2003 Elsevier B.V. All rights reserved. Keywords: Climate change; Stable isotopes; Carbon cycle; Isotope ratio mass spectrometry 1. Introduction Man has followed and tried to understand climate for millenia, primarily driven by the need to assign the appropriate times for sowing and harvesting or to determine the timing for food and fuel storage neces- sary to survive during winter. Since our contemporary ∗ Corresponding author. Tel.: +49-3641-576400; fax: +49-3641-5770. E-mail address: wbrand@bgc-jena.mpg.de (W.A. Brand). well-being still depends upon climate to some extent, there is a growing need to predict its future develop- ment at a range of temporal scales, its variability and associated potential hazards. Owing to external forcing, the Earth’s climatic sys- tem has always seen large variations [1–3]. Prediction of future climatic conditions will become possible pro- vided we have a reasonably thorough understanding of the physico-chemical processes that are operating on the Earth’s system. Detailed knowledge about the variability of physical and chemical processes driving 1387-3806/03/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S1387-3806(03)00289-6