Atmosphere-Snow Exchange Explains Surface Snow Isotope Variability

The climate signal imprinted in the snow isotopic composition allows to infer past climate variability from ice core stable water isotope records. The concurrent evolution of vapor and surface snow isotopic composition between precipitation events indicates that post-depositional atmosphere-snow humidity exchange influences the snow and hence the ice core isotope signal. To date, however, this is not accounted for in paeleoclimate reconstructions from isotope records. Here we show that vapor-snow exchange explains 36% of the summertime day-to-day delta O-18 variability of the surface snow between precipitation events, and 53% of the delta D variability. Through observations from the Greenland Ice Sheet and accompanying modeling we demonstrate that vapor-snow exchange introduces a warm bias on the summertime snow isotope value relevant for ice core records. In case of long-term variability in atmosphere-snow exchange the relevance for the ice core signal is also variable and thus paleoclimate reconstructions from isotope records should be revisited.

Automated summary

Research suggests that vapor-snow exchange influences surface snow isotopes during the summer, leading to biases in ice core records. This finding highlights the importance of considering the impact of vapor-snow exchange on signals when reconstructing paleoclimate from isotope records.