Abstract

Reconstructing the history of polar temperature from ice core water isotope (618O) calibration has remained a challenge in paleoclimate research, because of our incomplete understanding of various temperature-618O relationships. This paper resolves this classical problem in a new framework called... Show moreReconstructing the history of polar temperature from ice core water isotope (618O) calibration has remained a challenge in paleoclimate research, because of our incomplete understanding of various temperature-618O relationships. This paper resolves this classical problem in a new framework called the unified slope equations (USE), which illustrates the general relations among spatial and temporal 618O-surface temperature slopes. The USE is applied to the Antarctica temper-ature change during the last deglaciation in model simulations and observations. It is shown that the comparable Antarctica -mean spatial slope with deglacial temporal slope in 618O-surface temperature reconstruction is caused, accidentally, by the compensation responses between the 618O-inversion layer temperature relation and the inversion layer temperature itself. Furthermore, in light of the USE, we propose that the present seasonal slope of 618O-inversion layer temperature is an opti-mal paleothermometer that is more accurate and robust than the spatial slope. This optimal slope suggests the possibility of reconstructing past Antarctic temperature changes using present and future instrumental observations. Show less