Ice cores recovered from the polar regions of the Earth contain the most comprehensive, direct record of the Earth's high-latitude climate for the past 800,000 years. In addition to providing a proxy temperature record (through the record of the stable isotope ratios of water preserved in the ice) and a direct observational record of net accumulation, ice cores also provide the only direct record of atmospheric composition (direct gases, total gas content, and isotopic ratios) available in the field of paleoclimatology. As a result, the primary evidential basis for much of the current scientific thinking about past rates of climate change and the irrefutable evidence for the past linkage between atmospheric greenhouse gas concentrations and mean atmospheric temperature reside in the ice core record.
In its 2007 report, the UN's Intergovernmental Panel on Climate Change recognized the limited understanding of ice sheet dynamics (the motion and deformation of large bodies of ice) as a significant and poorly-characterized factor affecting our ability to model sea-level rise attributable to potential melting of the polar ice sheets. Studies of the physical properties of ice cores improve our understanding of how bodies of glacier ice respond to changes in accumulation rate, temperature, and external dynamics and provide constraints on the rates of those responses.
The interpretation of both the paleoclimate record and the past dynamical state of an ice sheet depends, in part, on the establishment of temporal continuity and a robust timescale, each of which can, in part, be determined from the analysis of the physical properties of an ice core recovered from it. The purpose of the work carried out in this task is to provide this analysis for ice cores recovered through the National Science Foundation's Office of Polar Programs from both the Arctic and Antarctic regions of the Earth.
The Ice Dynamics, Paleoclimate, and Ice Cores Project is funded by the Research and Development program of the USGS Climate and Land Use Change Program.
Objectives
- Provide understanding of the physical characteristics of ice sheets. Assess their stratigraphic continuity; identify anomalies that can potentially impact the interpretation of the climate records derived from them; reconstruct the flow history and the conditions for enhanced flow as an aid to reconstructing climate.
- Extract high-resolution hemispheric records of climate from ice cores to improve understanding of mechanisms of slow and abrupt climate change on glacial/interglacial and faster timescales.
- Collect a comprehensive suite of physical-property information to improve the general characterization of the past and present behavior of ice sheets.
- Participate in national and international field campaigns to acquire and provide analyses of the physical properties of deep ice cores from the polar regions.
- Contribute the results of laboratory analysis of physical properties of deep ice cores to national and international multi-disciplinary project teams working on creating high-resolution global climate history records.
- Develop numerical models for dynamic recrystallization and bubble evolution and assess their impact on ice dynamics.
- Ensure ready availability of analytical results to collaborators and team members through electronic dissemination of results.
Facilities
The Ice Dynamics, Paleoclimate, and Ice Cores Project maintains a laboratory for ice microstructure characterization at the U.S. National Ice Core Laboratory. Equipment for the preparation of thin and thick sections of ice includes:
- Bright field microscopy in plane polarized and cross-polarized light
- 90-degree illumination microscopy optimized for bubble characterization
- Reflected-light microscopy utilizing coaxial illumination
- Universal and Rigsby stages
- Digital image capture and video
- Fabric analysis is carried out in collaboration with the Ice and Climate Research Group at the Pennsylvania State University
Image processing and analysis software provide the capability to extract quantitative information from digital images, and microstructural modeling software is used to investigate the deformation and recrystallization mechanisms active at depth in an ice sheet. Microstructural visualization of measured parameters can be created in ArcGIS.
- Overview
Ice cores recovered from the polar regions of the Earth contain the most comprehensive, direct record of the Earth's high-latitude climate for the past 800,000 years. In addition to providing a proxy temperature record (through the record of the stable isotope ratios of water preserved in the ice) and a direct observational record of net accumulation, ice cores also provide the only direct record of atmospheric composition (direct gases, total gas content, and isotopic ratios) available in the field of paleoclimatology. As a result, the primary evidential basis for much of the current scientific thinking about past rates of climate change and the irrefutable evidence for the past linkage between atmospheric greenhouse gas concentrations and mean atmospheric temperature reside in the ice core record.
The Greenland Ice Sheet contains approximately 2.9 million km3 of ice that would raise sea level by about 7.3 m if it were to melt completely. (Credit: NASA) In its 2007 report, the UN's Intergovernmental Panel on Climate Change recognized the limited understanding of ice sheet dynamics (the motion and deformation of large bodies of ice) as a significant and poorly-characterized factor affecting our ability to model sea-level rise attributable to potential melting of the polar ice sheets. Studies of the physical properties of ice cores improve our understanding of how bodies of glacier ice respond to changes in accumulation rate, temperature, and external dynamics and provide constraints on the rates of those responses.
The interpretation of both the paleoclimate record and the past dynamical state of an ice sheet depends, in part, on the establishment of temporal continuity and a robust timescale, each of which can, in part, be determined from the analysis of the physical properties of an ice core recovered from it. The purpose of the work carried out in this task is to provide this analysis for ice cores recovered through the National Science Foundation's Office of Polar Programs from both the Arctic and Antarctic regions of the Earth.
The Ice Dynamics, Paleoclimate, and Ice Cores Project is funded by the Research and Development program of the USGS Climate and Land Use Change Program.
Objectives
- Provide understanding of the physical characteristics of ice sheets. Assess their stratigraphic continuity; identify anomalies that can potentially impact the interpretation of the climate records derived from them; reconstruct the flow history and the conditions for enhanced flow as an aid to reconstructing climate.
- Extract high-resolution hemispheric records of climate from ice cores to improve understanding of mechanisms of slow and abrupt climate change on glacial/interglacial and faster timescales.
- Collect a comprehensive suite of physical-property information to improve the general characterization of the past and present behavior of ice sheets.
- Participate in national and international field campaigns to acquire and provide analyses of the physical properties of deep ice cores from the polar regions.
- Contribute the results of laboratory analysis of physical properties of deep ice cores to national and international multi-disciplinary project teams working on creating high-resolution global climate history records.
- Develop numerical models for dynamic recrystallization and bubble evolution and assess their impact on ice dynamics.
- Ensure ready availability of analytical results to collaborators and team members through electronic dissemination of results.
Snowpits dug into the surface of an ice sheet reveal annual layers that can be identified hundreds of meters deep. Counting these layers provides one of several measurements used to create a robust timescale for an ice core. (Credit: Kendrick Taylor) Facilities
Joan Fitzpatrick at work in the U.S. National Ice Core Laboratory. The Ice Dynamics, Paleoclimate, and Ice Cores Project maintains a laboratory for ice microstructure characterization at the U.S. National Ice Core Laboratory. Equipment for the preparation of thin and thick sections of ice includes:
- Bright field microscopy in plane polarized and cross-polarized light
- 90-degree illumination microscopy optimized for bubble characterization
- Reflected-light microscopy utilizing coaxial illumination
- Universal and Rigsby stages
- Digital image capture and video
- Fabric analysis is carried out in collaboration with the Ice and Climate Research Group at the Pennsylvania State University
Image processing and analysis software provide the capability to extract quantitative information from digital images, and microstructural modeling software is used to investigate the deformation and recrystallization mechanisms active at depth in an ice sheet. Microstructural visualization of measured parameters can be created in ArcGIS.
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