Investigating the past and recent δ&amp;lt;sup&amp;gt;18&amp;lt;/sup&amp;gt;O-accumulation relationship seen in Greenland ice cores

S L Buchardt,D Dahl-Jensen,H B Clausen,B M Vinther

doi:10.5194/cp-8-2053-2012

Abstract

Abstract. Decadal means of δ18O and accumulation rates from 52 ice core locations in Greenland are presented. The accumulation rates are derived from annual layers determined in the δ18O curve. Investigation of the δ18O-accumulation relationship across the ice divide reveals a significant Foehn effect with anticorrelation of δ18O and accumulation rate on the lee side of the divide in Southern Greenland, while no effect is seen in Central Greenland. Furthermore, the sensitivity of accumulation rate to changes in temperature is found to be smaller in Northern Greenland than in the central and southern parts. Four records in the data set contain sufficient recent data that the period of observed temperature rise from the 1990s and onwards can be investigated. All four records are from locations close to the ice divide in Northern Greenland and while three of them show increased temperatures, no conclusive statement can be made about the accumulation rate from these data.

Highlights

During the last decades, global temperatures have increased and are affecting global sea level which is currently rising at a rate of 3.11 ± 0.6 mm yr−1 (1993–2008) (Ablain et al, 2009)
A data set consisting of decadal means of δ18O and accumulation rates derived from annual layers determined in the δ18O curves from 52 ice core locations in Greenland was presented
Using 10-yr averages of δ18O and accumulation rates for the 51 records from the main ice sheet, we found that no common δ18O-accumulation relation exists for Greenland

Summary

Introduction

Global temperatures have increased and are affecting global sea level which is currently rising at a rate of 3.11 ± 0.6 mm yr−1 (1993–2008) (Ablain et al, 2009). The Greenland ice sheet constitutes the second largest continental ice mass and holds enough ice to increase global sea level by 7 m if melted completely. Observations have shown that coastal temperatures in Greenland have increased over the last decades (Box, 2002), the area of surface melting is growing (Abdalati and Steffen, 2001) and the ice loss has been estimated to 205±50 Gt yr−1 (2005–2006) (AMAP, 2011). Regional climate model runs indicate that the rise in temperature should be followed by an increase in accumulation rate over the ice sheet, because the warmer air can contain more moisture (Box et al, 2006). Several authors have determined empirical relationships between temperature and accumulation rates that indicate that accumulation should increase with rising temperatures (Dahl-Jensen et al, 1993; Dansgaard et al, 1993; Johnsen et al, 1995). Dahl-Jensen et al (1993) used the following relation between accumulation rates and δ18O

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Conclusion