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Polar Region Bathymetry: Critical Knowledge for the Prediction of Global Sea Level Rise

Jakobsson, Martin and Mayer, Larry, 2022. Polar Region Bathymetry: Critical Knowledge for the Prediction of Global Sea Level Rise. Frontiers in Marine Science: 8:788724. doi: 10.3389/fmars.2021.788724

The ocean and the marine parts of the cryosphere interact directly with, and are affected by, the seafloor and its primary properties of depth (bathymetry) and shape (morphology) in many ways. Bottom currents are largely constrained by undersea terrain with consequences for both regional and global heat transport. Deep ocean mixing is controlled by seafloor roughness, and the bathymetry directly influences where marine outlet glaciers are susceptible to the inflow relatively warm subsurface waters - an issue of great importance for ice-sheet discharge, i.e., the loss of mass from calving and undersea melting. Mass loss from glaciers and the Greenland and Antarctic ice sheets, is among the primary drivers of global sea-level rise, together now contributing more to sea-level rise than the thermal expansion of the ocean. Recent research suggests that the upper bounds of predicted sea-level rise by the year 2100 under the scenarios presented in IPCC’s Special Report on the Ocean and Cryosphere in a Changing Climate (SROCCC) likely are conservative because of the many unknowns regarding ice dynamics. In this paper we highlight the poorly mapped seafloor in the Polar regions as a critical knowledge gap that needs to be filled to move marine cryosphere science forward and produce improved understanding of the factors impacting ice-discharge and, with that, improved predictions of, among other things, global sea-level. We analyze the bathymetric data coverage in the Arctic Ocean specifically and use the results to discuss challenges that must be overcome to map the most remotely located areas in the Polar regions in general.

illustration of marine outlet glacier ending in an ice tongue
Figure 1. The main components of the “marine cryosphere,” here defined as including marine outlet glaciers ending in floating ice tongues/shelves or grounded ice cliffs, icebergs, ice sheets with their base suppressed below sea level, sea ice, gas hydrates and submarine permafrost. The floating extensions of marine outlet glaciers found in fjords are here referred to as ice tongues, while the wider floating extensions, primarily existing today in Antarctica, are called ice shelves. Permafrost and gas hydrates are part of the marine cryosphere, but not discussed much further in this work.