Modeling Long-Term Changes in Climate, Ice Sheets and Sea Level: Using the Paleo Record to Understand Possibilities for the Future
The paleoclimate record highlights the susceptibility of ice sheets and sea level to increased global temperatures, even for global warming much less severe than that predicted for future climate. The critical role of climate feedbacks in regulating ice sheets over centuries and millennia highlights...
| Main Authors: | , , , , , , , , |
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| Language: | unknown |
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2020
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| Online Access: | http://www.osti.gov/servlets/purl/1714361 https://www.osti.gov/biblio/1714361 https://doi.org/10.2172/1714361 |
| Summary: | The paleoclimate record highlights the susceptibility of ice sheets and sea level to increased global temperatures, even for global warming much less severe than that predicted for future climate. The critical role of climate feedbacks in regulating ice sheets over centuries and millennia highlights the need to use coupled ice-sheet/climate models in assessments of past and future sea level rise. However, coupled climate models are only beginning to include dynamic ice sheets, coupling mechanisms between ice sheets and climate, and the spatial resolution needed to properly simulate the coupled ice-sheet/climate system. During this project, we completed the development and testing of the infrastructure for coupled CESM2-CISM2 paleo-simulations of the Greenland ice sheet. The Community Earth System Model (CESM) is a fully coupled, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate states. The newest version, CESM2, contributed simulations to the Coupled Model Intercomparison Project Phase 6 (CMIP6). The ice sheet component of CESM2 is the Community Ice Sheet Model Version 2.1 (CESM2.1), a parallel, scalable code with a suite of higher-order ice-flow solvers that are physically realistic for all parts of an ice sheet, including fast-flowing ice streams and outlet glaciers. The incorporation of a physically based “pseudo-plastic” basal sliding scheme gives realistic velocities over most of the Greenland ice sheet, while allowing basal conditions to evolve on multi-century time scales. Additional processes and feedbacks important for long, coupled, millennial-scale simulations – evolving topography, orbital acceleration, asynchronous coupling to dynamic vegetation – have been implemented. The preindustrial ice sheet/Earth system state is achieved via a new, efficient, interactive spin-up method and provides initial conditions for transient paleo-simulations with CESM2-CISM2, as well as the ISMIP6 coupled historical and future simulations. Taking ... |
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