RECONSTRUCTION OF CLIMATE AND
ENVIRONMENTAL CHANGES

Introduction

The climate of our planet is expected to change significantly within the next century due to the increasing greenhouse effect. Our expectations are mainly based on model calculations, but it is also possible to reconstruct the response of the global climate system to certain disturbances by investigating past global changes. Excellent archives of such changes are the polar ice sheets. The analyses of ice cores drilled in the central parts of the large ice sheets do not only allow to reconstruct the local temperature, the annual precipitation rate or other regional environmental parameters but also the composition of the atmosphere in the past.

Analytical methods

With our Continuous Flow Analysis (CFA) system we are able to record continuous, highly resolved (< 1cm) concentration profiles of different tracers incorporated in the ice. This is achieved by melting the ice samples continuously and analysing the meltwater online and simultaneously for the different chemical species. At the moment the following species can be measured: H₂O₂, HCHO, NH₄⁺, Ca²⁺, NO₃^-, Na⁺ and total conductivity. Most of them are analysed by fluorescence or absorption spectrometry. These measurements are performed in the field directly after drilling the ice cores in order to prevent contamination during transport and storage.

We are also able to measure the CO₂ and CH₄ concentration and the isotopic composition (e.g. d¹³C of CO₂ and d¹⁸O of O₂) of the air which is enclosed in bubbles or in air hydrates. To measure the CO₂ concentration an ice sample is broken into small pieces in vacuum; the extracted air is measured with Infrared Laser Spectroscopy. For the CH₄ measurements we are melting the ice samples in an evacuated glass container; CH₄ is detected with a Gaschromatograph. For the isotopic analysis the ice is ground in vacuum with a milling cutter; analysis is performed with Mass Spectrometry.

Projects

We are involved in the following projects:

• Greenland Icecore Project (GRIP)
• European Project for Ice Coring in Antarctica (EPICA)
• Environmental and Climate Records from High Elevation Alpine Glaciers (ALPCLIM)

Related research groups

• Department of Geophysics - University of Copenhagen
• Laboratoire de Glaciologie et Géophysique de l' Environnement (LGGE), Grenoble
• Alfred Wegener Institut, Bremerhaven
• Eisgruppe, Institut für Umweltphysik, Ruprecht-Karls-Universität Heidelberg
• Geosciences Research Division, Scripps Institution of Oceanography, San Diego

Data

• GRIP/GISP2 CD
• NEW: GISP2-GRIP synchronisation. Description of the method; Data