Reversibility of the Hydrological Response in East Asia from CO2-Derived Climate Change Based on CMIP6 Simulation

Abstract

Understanding the response of the Earth system to CO2 removal (CDR) is crucial because the possibility of irreversibility exists. Therefore, the Carbon Dioxide Removal Model Inter-comparison Project (CDRMIP) for the protocol experiment in the Coupled Model Inter-comparison Project Phase 6 (CMIP6) has been developed. Our analysis focuses on the regional response in the hydrological cycle, especially in East Asia (EA). The peak temperature changes in EA (5.9 K) and the Korean peninsula (KO) (6.1 K) are larger than the global mean surface air temperature (GSAT) response. The precipitation changes are approximately 9.4% (EA) and 23.2% (KO) at the phase change time (130–150 years); however, the largest increase is approximately 16.6% (EA) and 36.5% (KO) in the ramp-down period (150–160 years). In addition, the differences are below 5 mm/day and 1 day for the precipitation intensity indices (Rx1day and Rx5day) and frequency indices (R95 and R99), respectively. Furthermore, the monsoon rainband of the ramp-down period moves northward as the earlier onset with high confidence compared to the ramp-up period; however, it does not move north to the KO region. The results suggest that reducing CO2 moves the rainband southward. However, a detailed interpretation in terms of the mechanism needs to be carried out in further research.

Contrasting Hysteresis Behaviors of Northern Hemisphere Land Monsoon Precipitation to CO2 Pathways

“…Similarly, Sun et al. (2021) found that responses of monsoon precipitation over East Asia from the Carbon Dioxide Removal Model Intercomparison Project (CDRMIP; Keller et al., 2018) had a strong locality. However, studies on whether and how monsoon precipitation would respond to reduced CO 2 emissions are still needed.…”

“…Song et al (2022) demonstrated that the East Asian monsoon precipitation asymmetrically responded to CO 2 RUP and RDN forcing; they argued that such temporally asymmetrical response is due to a tropical-subtropical SST response, including an enhanced El Niño-like SST warming and a meridional SST gradient over the western North Pacific. Similarly, Sun et al (2021) found that responses of monsoon precipitation over East Asia from the Carbon Dioxide Removal Model Intercomparison Project (CDRMIP; Keller et al, 2018) had a strong locality. However, studies on whether and how monsoon precipitation would respond to reduced CO 2 emissions are still needed.…”

A weakened AMOC may prolong greenhouse gas–induced Mediterranean drying even with significant and rapid climate change mitigation

“…A particularly important question is the extent to which climate change would be reversed if greenhouse gas concentrations were to substantially decline later this century ( 7 , 8 ). Are there climate system changes that would not be reversed in response to significant reductions in emissions ( 8 – 23 )? Have any such components crossed thresholds from which recovery may be difficult?…”

Hysteretic Behavior of Global to Regional Monsoon Area Under CO2 Ramp‐Up and Ramp‐Down

“…Sun et al. (2021) also reported persistent summer PR increases in EAS and Korean Peninsula in early RD period.…”