A revised +10±4 °C magnitude of the abrupt change in Greenland temperature at the Younger Dryas termination using published GISP2 gas isotope data and air thermal diffusion constants

We revisit the portion of (Nature 391 (1998) 141) devoted to the abrupt temperature increase reconstruction at the Younger Dryas/Preboreal transition. The original estimate of +5 to +10 °C abrupt warming is revised to +10±4 °C. The gas isotope data from the original work were employed, combined with recently measured precise air thermal diffusion constants (Geochim. Cosmochim. Acta 67 (2003a) 345; J. Phys. Chem. 23A (2003b) 4636). The new constants allow a robust interpretation of the gas isotope signal in terms of temperature change. This was not possible at the time of the original work, when no air constants were available. Three quasi-independent approaches employed in this work all give the same result of a +10 °C warming in several decades or less. The new result provides a firm target for climate models that attempt to predict future climates.