Cascading oxygen loss shoreward in the oceans: Insights from the Cambrian SPICE event

TY - JOUR

T1 - Cascading oxygen loss shoreward in the oceans

T2 - Insights from the Cambrian SPICE event

AU - Sørensen, Aske L.

AU - Dahl, Tais W.

PY - 2024/6/21

Y1 - 2024/6/21

N2 - Marine euxinia can amplify phosphorous-limited marine productivity by recycling phosphorous from sediments, creating a feedback loop that increases marine oxygen consumption and ultimately leads to widespread oceanic anoxia. This phenomenon is potentially more dangerous when oxygen loss arises in coastal zones. Here, we present empirical evidence and show that this cascade was set off in the Cambrian Earth system. Carbon isotopes and Mo enrichments in well-dated sediment records from the Steptoean Positive Carbon Isotope Excursion (SPICE) event reveal a rapid decline over 130 ± 30 ka to persistently low Mo levels for 1.0 ± 0.2 Ma, followed by a slower recovery. Using dynamic models for the global biogeochemical cycles, we demonstrate that marine anoxia expanded globally through a self-cascading feedback mechanism. Importantly, we find that the benthic phosphorous flux likely scaled with sedimentation, and that chemocline shoaling into coastal areas likely triggered the SPICE event. We evaluate the risk of passing the tipping point for global-scale anoxia today.

AB - Marine euxinia can amplify phosphorous-limited marine productivity by recycling phosphorous from sediments, creating a feedback loop that increases marine oxygen consumption and ultimately leads to widespread oceanic anoxia. This phenomenon is potentially more dangerous when oxygen loss arises in coastal zones. Here, we present empirical evidence and show that this cascade was set off in the Cambrian Earth system. Carbon isotopes and Mo enrichments in well-dated sediment records from the Steptoean Positive Carbon Isotope Excursion (SPICE) event reveal a rapid decline over 130 ± 30 ka to persistently low Mo levels for 1.0 ± 0.2 Ma, followed by a slower recovery. Using dynamic models for the global biogeochemical cycles, we demonstrate that marine anoxia expanded globally through a self-cascading feedback mechanism. Importantly, we find that the benthic phosphorous flux likely scaled with sedimentation, and that chemocline shoaling into coastal areas likely triggered the SPICE event. We evaluate the risk of passing the tipping point for global-scale anoxia today.

KW - animal habitable zone

KW - biogeochemical cycles

KW - chemocline shoaling

KW - climate dynamics

KW - cyclostratigraphy

KW - global marine redox proxy

KW - marine anoxia

KW - oceanic anoxic events

KW - sedimentation

KW - tipping point

UR - http://www.scopus.com/inward/record.url?scp=85196260923&partnerID=8YFLogxK

U2 - 10.1016/j.oneear.2024.05.011

DO - 10.1016/j.oneear.2024.05.011

M3 - Journal article

AN - SCOPUS:85196260923

SN - 2590-3330

VL - 7

SP - 1108

EP - 1120

JO - One Earth

JF - One Earth

IS - 6

ER -