In:
Journal of Climate, American Meteorological Society, Vol. 36, No. 19 ( 2023-10-01), p. 6613-6630
Abstract:
Tipping points in the Earth system describe critical thresholds beyond which a single component, part of the system, or the system as a whole changes from one stable state to another. In the present-day Southern Ocean, the Weddell Sea constitutes an important dense-water formation site, associated with efficient deep-ocean carbon and oxygen transfer and low ice-shelf basal melt rates. Here, a regime shift will occur when continental shelves are continuously flushed with warm, oxygen-poor offshore waters from intermediate depth, leading to less efficient deep-ocean carbon and oxygen transfer and higher ice-shelf basal melt rates. We use a global ocean–biogeochemistry model including ice-shelf cavities and an eddy-permitting grid in the southern Weddell Sea to address the susceptibility of this region to such a system change for four twenty-first-century emission scenarios. Assessing the projected changes in shelf–open-ocean density gradients, bottom-water properties, and on-shelf heat transport, our results indicate that the Weddell Sea undergoes a regime shift by 2100 in the highest-emission scenario, SSP5–8.5, but not yet in the lower-emission scenarios. The regime shift is imminent by 2100 in the scenarios SSP3–7.0 and SSP2–4.5, but avoidable under the lowest-emission scenario SSP1–2.6. While shelf-bottom waters freshen and acidify everywhere, bottom waters in the Filchner Trough undergo accelerated warming and deoxygenation following the system change, with implications for local ecosystems and ice-shelf basal melt. Additionally, deep-ocean carbon and oxygen transfer decline, implying that the local changes ultimately affect ocean circulation, climate, and ecosystems globally.
Type of Medium:
Online Resource
ISSN:
0894-8755
,
1520-0442
DOI:
10.1175/JCLI-D-22-0926.1
DOI:
10.1175/JCLI-D-22-0926.s1
Language:
Unknown
Publisher:
American Meteorological Society
Publication Date:
2023
detail.hit.zdb_id:
246750-1
detail.hit.zdb_id:
2021723-7
