A modified viscous flow law for natural glacier ice: Scaling from laboratories to ice sheets

• 成果类型: Article
• 署名作者: Ranganathan, Meghana; Minchew, Brent
• 署名单位: Massachusetts Institute of Technology (MIT); University System of Georgia; Georgia Institute of Technology
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12592
• DOI: 10.1073/pnas.2309788121
• 发表日期: 2024-06-04
• 关键词: polar ice; dynamic recrystallization; creep deformation; shear margins; grain-growth; rheology; stream; EVOLUTION; island; temperature

摘要

Glacier flow modulates sea level and is governed largely by the viscous deformation ice. Multiple molecular -scale mechanisms facilitate viscous deformation, but it remains unclear how each contributes to glacier -scale deformation. Here, we present a model ice deformation that bridges laboratory and glacier scales, unifies existing estimates the viscous parameters, and provides a framework for estimating the parameters from observations and incorporating flow laws derived from laboratory observations glacier -flow models. Our results yield a map of the dominant deformation mechanisms in the Antarctic Ice Sheet, showing that, contrary to long-standing assumptions, dislocation creep, characterized by a value of the stress exponent n = 4, likely dominates in all fast -flowing areas. This increase from the canonical value of n dramatically alters the climate conditions under which marine ice sheets may become unstable and drive rapid rates of sea -level rise.