The reversibility of global mean surface temperature was examined by a transient CO2 reversibility experiment using an Earth system model. The results showed that after CO2 ramp-up toward CO2 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 CO2 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 CO2 forcing. During the progression of CO2 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.
|Publication status||Published - 2021 Jul|
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF‐2018R1A5A1024958). The CESM simulation was carried out on the supercomputer supported by the National Center for Meteorological Supercomputer of Korea Meteorological Administration (KMA), the National Supercomputing center with supercomputing resources, associated technical support (KSC‐2019‐CHA‐0005), and the Korea Research Environment Open NETwork (KREONET).
© 2021. The Authors. Earth's Future published by Wiley Periodicals LLC on behalf of American Geophysical Union.
All Science Journal Classification (ASJC) codes
- Environmental Science(all)
- Earth and Planetary Sciences (miscellaneous)