In particular, our global review reinforces the finding of several single noble gas case studies that the tropics were substantially cooler during the last glacial maximum than at present. Noble gases in the atmosphere are chemically and biologically inactive and have no appreciable sinks or sources over the 40,000-year timescales relevant to this study. “Another key goal of our study was to evaluate the overall accuracy of the so-called ‘noble gas paleo-thermometer’ for reconstructing temperatures on land during the last glacial period. Seltzer added that the new analysis is important because climate models “provide an important tool that policy makers can use to decide on how to prepare for future environmental changes. This study alleviates the concern that, based on LGM proxy data, models might over-predict the global mean temperature response to carbon dioxide.