VPL researchers Josh Krissansen-Totton and David Catling have published an article in the journal Nature titled "Constraining climate sensitivity and continental versus seafloor weathering with an inverse geological carbon cycle model" (doi:10.1038/ncomms15423). Theyexamined indicators in the rocks of past temperatures, atmospheric CO2 levels, and other environmental quantities, going back from today to 100 million years ago, when 70-ton dinosaurs roamed around ice-free polar regions. Their analysis found that the Earth system has much poorer "thermostat” from rock weathering tha previously thought and allows fairly big swings in temperature. Also, in the very long-term, the rocks show that global temperatures go up around 5 or 6 C for CO2 doublings, which is about twice the 3 C that's projected on timescales of centuries for global warming. Having tested a geologic carbon cycle model on a fairly data-rich period of Earth history, such analysis can now be applied with more confidence to understand the climate of the very early Earth when life was just starting or the habitability of Earth-like exoplanets.