Open AccessGlobal Cooling Hiatus Driven by an AMOC Overshoot in a Carbon Dioxide Removal Scenario
Author(s) -
An SoonIl,
Shin Jongsoo,
Yeh SangWook,
Son SeokWoo,
Kug JongSeong,
Min SeungKi,
Kim HyoJeong
Publication year - 2021
Publication title -
earth's future
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.641
H-Index - 39
ISSN - 2328-4277
DOI - 10.1029/2021ef002165
Subject(s) - climatology , northern hemisphere , advection , thermohaline circulation , overshoot (microwave communication) , environmental science , southern hemisphere , global warming , zonal and meridional , forcing (mathematics) , atmospheric sciences , oceanography , geology , climate change , physics , engineering , electrical engineering , thermodynamics
The reversibility of global mean surface temperature was examined by a transient CO 2 reversibility experiment using an Earth system model. The results showed that after CO 2 ramp‐up toward CO 2 quadrupling and ramp‐down returned to the present‐day level, the global mean surface temperature kept decreasing but stopped to change for ∼40 years in the early net‐zero CO 2 emission period. This period, referred to a cooling hiatus, resulted from a compensation between Southern Hemisphere cooling and Northern Hemisphere warming. The Northern Hemisphere warming was centered over the North Atlantic. This localized warming was caused by an excessive heat advection by a delayed and surpassed Atlantic Meridional Overturning Circulation (AMOC) to CO 2 forcing. During the progression of CO 2 change, the meridional salinity gradient between subtropic and subpolar regions was enhanced, and the oceanic stratification in subpolar North Atlantic was reduced due to accumulated heat and reduced vertical salt import in the deeper ocean. As AMOC started to recover, consequently, the enhanced salt advection feedback and the relaxed buoyant force resulted in AMOC overshoot.