AMOC Stabilization under the Interaction with Tipping Polar Ice Sheets

Abstract

Global warming is one of the main threats to the stability of the present-day climate system. Under this warming, specific climate system components might change abruptly when certain critical thresholds are exceeded. Examples of such tipping elements (Lenton et al., 2008) are the Greenland Ice Sheet (GIS), the Atlantic Meridional Overturning Circulation and the West Antarctic Ice Sheet (WAIS). A thorough understanding of the mechanisms and impact of tipping behavior in these subsystems is fundamental in assessing the risks of climate change (Kemp et al., 2022). Tipping elements are also strongly interacting, for example, the polar ice sheets and the ocean circulation, and hence tipping in one subsystem (the leading system) may lead to tipping in another (the following system), in a so-called tipping cascade (Dekker et al., 2018). This rises the possibility of domino effects, causing the climate system to collapse while the threshold of one subsystem only has been crossed (Klose et al., 2021). However, the collapse of one subsystem may also stabilize others (

AMOC Stabilization Under the Interaction With Tipping Polar Ice Sheets

“…However, we can expect our qualitative results to hold as long as this interaction remains destabilizing. To better base it on physical grounds, one would have to consider sub-shelf melting and calving processes, interacting with the ice shelf stability through buttressing (Haseloff & Sergienko, 2018, 2022 and lateral drag (Schoof et al, 2017). Also, a better assessment of the fraction f of the WAIS freshwater flux reaching the southern Atlantic Ocean would be a direct improvement, which involves resolving the dynamics associated to the Antarctic Circumpolar Current and is beyond the scope of this study.…”

“…All MATLAB codes are publicly available (Sinet, 2022), at the address: https://doi.org/10.5281/zenodo.6800055, including a short manual.…”

AMOC Stability Amid Tipping Ice Sheets: The Crucial Role of Rate and Noise

“…The experimental setup is presented in section 2. In section 3, we reproduce a set of model simulations similar to Sinet et al (2023), yielding a qualitatively similar AMOC stabilization effect of the WAIS meltwater flux. In section 4, the bifurcation structure of the model is presented, allowing us to identify the presence of rate-induced effects.…”

“…There, many different processes are at play and might either tend to destabilize it or keep it from collapsing (Swingedouw et al, 2009;Berk et al, 2021). In a conceptual model representing the AMOC and both polar ice sheets, Sinet et al (2023) recently showed that the WAIS meltwater flux is able to prevent an AMOC collapse against the destabilization caused by both climate warming and ice loss from the GIS. The occurrence of an AMOC collapse drastically depends on the rate of forcing, as well as on the time delay between the tipping of both ice sheets.…”

“…Motivated by the WAIS induced stabilization effect on the AMOC found by Sinet et al (2023), we explore its relevance in a more comprehensive conceptual model of the AMOC, considering also the stochastic case. For this, we perform a variety of model simulations using a simplified representation of tipping ice sheets.…”