When was Greenland ‘green’? – Perspectives from basal ice and sediments from ice cores.

Introduction

Green2Ice will investigate the deepest and oldest ice and basal sediments drilled from the Greenland Ice Sheet (GrIS). Ice cores have been drilled for the last 55 years, but the deepest ice containing basal materials has been preserved until now and still holds undeciphered paleoclimatic messages.

Objectives

The breakthrough of Green2Ice is to develop and apply cutting-edge dating methods on this unique sample collection and hence to reconstruct the age and the stability of the GrIS. A hypothesis to test is if the present GrIS formed at the time of the Mid Pleistocene Transition, 1.2 - 0.8 million years ago.

Innovations

One innovation of Green2Ice is to gain paleo-information of the past size of the GrIS to constrain future tipping points. This knowledge will reduce the uncertainty on estimates of future sea level rise.

Collaboration

Green2Ice will bring together four PIs from three world-leading institutions with complementary skills to lift this strongly interdisciplinary program.

Methodology

1. We will drill a replicate core at GRIP to supplement the available material from five existing ice cores and ensure retrieval of sediments and rock material from beneath the GrIS summit.
2. We will develop, improve, and apply novel dating techniques (cosmogenic and radiogenic nuclides, OSL/IRSL, modeling of gas and isotope diffusion) to place constraints on past waxing and waning of the GrIS.
3. State-of-the-art methodologies on fossil remains, organic matter, in situ produced and consumed greenhouse gases, and ancient bio-molecules will provide insights on the types of ecosystems and environmental conditions that emerged during ice-free conditions.

Data Interpretation

Interpretation will include ice sheet modeling with data benchmarking to establish the climatic sensitivity of the GrIS. Earth system modeling and collaboration with the groups preparing the IPCC AR7 will bring the knowledge of the past into the future.

Risks and Gains

The rare and unique basal ice and material can only be used once. This is the main high-risk, high-gain component of Green2Ice.