|"Kudos to Greg Hoke (along with colleagues Nate Peters and Kate Huntington at the University of Washington) for their recent paper in EPSL: “Hot or not? Impact of seasonally variable soil carbonate formation on paleotemperature and O-isotope records from clumped isotope thermometry”. This is good stuff. It turns out that many soils contain carbonate-rich units developed during evapotranspiration and pedogenesis, and the oxygen isotope composition of these soil carbonates can therefore shed light on temperatures (think elevation and climate) of formation. Greg and coworkers investigated the relation between seasonally-variable soil temperatures and carbonate formation temperatures using clumped isotope thermometry. They found that clumped isotope values for soil carbonates collected at higher elevations reflect summer soil temperatures, but that those at lower elevations track mean annual soil temperature, a result that may reflect the dominance of summer precipitation at low elevations, a factor which may delay soil drying and carbonate growth until fall. Although such seasonal bias can prevent the straightforward translation of soil carbonate isotope values into meaningful surface air temperatures, the study provides direct constraints on temperature from clumped isotopes that can provide a window into soil processes, and that can aid in the interpretation of conventional stable isotopic data to reconstruct surface conditions in the past."