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  • 1
    Online Resource
    Online Resource
    Slow and soft passage through tipping point of the Atlantic Meridional Overturning Circulation in a changing climate
    Springer Science and Business Media LLC ; 2022
    In:  npj Climate and Atmospheric Science Vol. 5, No. 1 ( 2022-02-11)
    Details
    In: npj Climate and Atmospheric Science, Springer Science and Business Media LLC, Vol. 5, No. 1 ( 2022-02-11)
    Abstract: Paleo-proxy records suggest that the Atlantic Meridional Overturning Circulation (AMOC) exhibits a threshold for an abrupt change, a so-called tipping point. A classical bifurcation theory, a basis of the tipping dynamics of AMOC implicitly assumes that the tipping point is fixed. However, when a system is subjected to time-varying forcing (e.g., AMOC exposed to ice meltwater) an actual tipping point can be overshot due to delayed tipping, referred to as the slow passage effect. Here, using an Earth system model of intermediate complexity and a low-order model with freshwater forcing, we show that the tipping point of AMOC is largely delayed by the slow passage effect. It causes a large tipping lag of up to 1300 years, and strongly relaxes the abruptness of tipping as well. We further demonstrate that the tipping modulation can actively occur in past, present, and future climates by quantifying the effect during Dansgaard-Oeschger events, meltwater pulse 1A (MWP-1A), and current Greenland ice sheet melting. The suggested slow passage effect may explain the observed lagged AMOC collapse to MWP-1A of about 1000 years and provides implications tipping risk in the future.
    Type of Medium: Online Resource
    ISSN: 2397-3722
    URL: Article
    DOI: 10.1038/s41612-022-00236-8
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2925628-8
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  • 2
    Online Resource
    Online Resource
    Feedback processes modulating the sensitivity of Atlantic thermohaline circulation to freshwater forcing timescales
    American Meteorological Society ; 2021
    In:  Journal of Climate ( 2021-03-26), p. 1-36
    Details
    In: Journal of Climate, American Meteorological Society, ( 2021-03-26), p. 1-36
    Abstract: Paleo proxy records indicate that abrupt changes in thermohaline circulation (THC) were induced by rapid meltwater discharge from retreating ice sheets. Such abrupt changes in the THC have been understood as a hysteresis behavior of nonlinear system. Previous studies, however, primarily focused on a near-static hysteresis under fixed or slowly varying freshwater forcing (FWF), reflecting the equilibrated response of the THC. This study aims to improve the current understanding of transient THC responses under rapidly varying forcing and its dependency on forcing timescales. The results simulated by an Earth system model suggest that the bifurcation is delayed as the forcing timescale is shorter, causing the Atlantic meridional overturning circulation collapse (recovery) to occur at higher (lower) FWF values. The delayed shutdown/recovery occurs because bifurcation is determined not by the FWF value at the time but by the total amount of freshwater remaining over the THC convection region. The remaining freshwater amount is primarily determined by the forcing accumulation (i.e., time-integrated FWF), which is modulated by the freshwater/salt advection by ocean circulations and freshwater flux by the atmospheric hydrological cycle. In general, the latter is overwhelmed by the former. When the forced freshwater amount is the same, the modulation effect is stronger under slowly varying forcing because more time is provided for the feedback processes.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-20-0897.1
    RVK:
    UA 4548
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2021
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 3
    Online Resource
    Online Resource
    Seasonal Gap Theory for ENSO Phase Locking
    American Meteorological Society ; 2021
    In:  Journal of Climate ( 2021-04-12), p. 1-44
    Details
    In: Journal of Climate, American Meteorological Society, ( 2021-04-12), p. 1-44
    Abstract: The life cycle of El Niño-Southern Oscillation (ENSO) typically follows a seasonal march, onset in spring, developing during summer, maturing in boreal winter, and decaying over the following spring. This feature is referred to as ENSO phase locking. Recent studies have noted that seasonal modulation of the ENSO growth rate is essential for this process. This study investigates the fundamental effect of a seasonally varying growth rate on ENSO phase locking using a modified seasonally-dependent recharge oscillator model. There are two phase locking regimes associated with the strength of the seasonal modulation of growth rate: (1) a weak regime in which only a single peak occurs; and (2) a strong regime in which two types of events occur either with a single peak or double peak. Notably, there is a seasonal gap in the strong regime, during which the ENSO peak cannot occur because of large-scale ocean-atmosphere coupled processes. We also retrieve a simple analytical solution of the seasonal variance of ENSO, revealing that the variance is governed by the time-integral of seasonally varying growth rate. Based on this formulation, we propose a seasonal energy index (SEI) that allows explaining the seasonal gap, and provides an intuitive explanation for ENSO phase locking, potentially applicable to global climate model ENSO diagnostics.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-20-0495.1
    RVK:
    UA 4548
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2021
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 4
    Online Resource
    Online Resource
    Hysteresis and irreversibility of global extreme precipitation to anthropogenic CO2 emission
    Elsevier BV ; 2023
    In:  Weather and Climate Extremes Vol. 40 ( 2023-06), p. 100561-
    Details
    In: Weather and Climate Extremes, Elsevier BV, Vol. 40 ( 2023-06), p. 100561-
    Type of Medium: Online Resource
    ISSN: 2212-0947
    URL: Article
    DOI: 10.1016/j.wace.2023.100561
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 2732464-3
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  • 5
    Online Resource
    Online Resource
    Widespread irreversible changes in surface temperature and precipitation in response to CO2 forcing
    Springer Science and Business Media LLC ; 2022
    In:  Nature Climate Change Vol. 12, No. 9 ( 2022-09), p. 834-840
    Details
    In: Nature Climate Change, Springer Science and Business Media LLC, Vol. 12, No. 9 ( 2022-09), p. 834-840
    Abstract: Some climate variables do not show the same response to declining atmospheric CO 2 concentrations as before the preceding increase. A comprehensive understanding of this hysteresis effect and its regional patterns is, however, lacking. Here we use an Earth system model with an idealized CO 2 removal scenario to show that surface temperature and precipitation exhibit globally widespread irreversible changes over a timespan of centuries. To explore the climate hysteresis and reversibility on a regional scale, we develop a quantification method that visualizes their spatial patterns. Our experiments project that 89% and 58% of the global area experiences irreversible changes in surface temperature and precipitation, respectively. Strong irreversible response of surface temperature is found in the Southern Ocean, Arctic and North Atlantic Ocean and of precipitation in the tropical Pacific, global monsoon regions and the Himalayas. These global hotspots of irreversible changes can indicate elevated risks of negative impacts on developing countries.
    Type of Medium: Online Resource
    ISSN: 1758-678X , 1758-6798
    URL: Article
    DOI: 10.1038/s41558-022-01452-z
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2603450-5
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  • 6
    Online Resource
    Online Resource
    Fokker–Planck dynamics of the El Niño-Southern Oscillation
    Springer Science and Business Media LLC ; 2020
    In:  Scientific Reports Vol. 10, No. 1 ( 2020-10-01)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2020-10-01)
    Abstract: The asymmetric nature of the El Niño-Southern Oscillation (ENSO) is explored by using a probabilistic model (PROM) for ENSO. Based on a Fokker–Planck Equation (FPE), PROM describes the dynamics of a nonlinear stochastic ENSO recharge oscillator model for eastern equatorial Pacific temperature anomalies and equatorial Pacific basin-averaged thermocline depth changes. Eigen analyses of PROM provide new insights into the stationary and oscillatory solutions of the stochastic dynamical system. The first probabilistic eigenmode represents a stationary mode, which exhibits the asymmetric features of ENSO, in case deterministic nonlinearities or multiplicative noises are included. The second mode is linked to the oscillatory nature of ENSO and represents a cyclic asymmetric probability distribution, which emerges from the key dynamical processes. Other eigenmodes are associated with the temporal evolution of higher order statistical moments of the ENSO system. The model solutions demonstrate that the deterministic nonlinearity plays a stronger role in establishing the observed asymmetry of ENSO as compared to the multiplicative stochastic part.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-020-73449-7
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2615211-3
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  • 7
    Online Resource
    Online Resource
    Hysteresis of the El Niño–Southern Oscillation to CO 2 forcing
    American Association for the Advancement of Science (AAAS) ; 2023
    In:  Science Advances Vol. 9, No. 31 ( 2023-08-02)
    Details
    In: Science Advances, American Association for the Advancement of Science (AAAS), Vol. 9, No. 31 ( 2023-08-02)
    Abstract: CO 2 reduction leads to even stronger eastern Pacific ENSO SST variability and global impacts compared to CO 2 increase.
    Type of Medium: Online Resource
    ISSN: 2375-2548
    URL: Article
    DOI: 10.1126/sciadv.adh8442
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2023
    detail.hit.zdb_id: 2810933-8
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  • 8
    Online Resource
    Online Resource
    Intensity changes of Indian Ocean dipole mode in a carbon dioxide removal scenario
    Springer Science and Business Media LLC ; 2022
    In:  npj Climate and Atmospheric Science Vol. 5, No. 1 ( 2022-03-21)
    Details
    In: npj Climate and Atmospheric Science, Springer Science and Business Media LLC, Vol. 5, No. 1 ( 2022-03-21)
    Abstract: The Indian Ocean Dipole/Zonal mode (IOD) is an interannual phenomenon over the tropical Indian Ocean, causing a pronounced impact worldwide. Here, we investigate the mechanism of the change in IOD characteristics in a CO 2 removal simulation for an earth system model (ESM). As the CO 2 concentration increases, the intensity of IOD tends to increase, but at high CO 2 concentrations, further increases decrease the IOD intensity. The minimum IOD amplitude was recorded during the early decrease in CO 2 . First, we developed a conceptual model for IOD that is composed of local air-sea coupled feedback, delayed ocean dynamics, El Niño impact, and noise forcing. Then, by adopting ESM results into this simple IOD model, we revealed that the local air–sea coupled feedback is a major factor for changing IOD amplitude, while El Niño does not exert a change in IOD amplitude. The local air–sea coupled feedback including thermocline feedback, wind-evaporation feedback, and Ekman feedback is strongly modified by the air–sea coupling strength during progression of a global warming. Consequently, under the higher CO 2 concentrations, IOD amplitude is reduced due to the weakening of air-sea coupling over tropical Indian Ocean.
    Type of Medium: Online Resource
    ISSN: 2397-3722
    URL: Article
    DOI: 10.1038/s41612-022-00246-6
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2925628-8
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  • 9
    Online Resource
    Online Resource
    Emergent constraints on future extreme precipitation intensification: from global to continental scales
    Elsevier BV ; 2023
    In:  Weather and Climate Extremes Vol. 42 ( 2023-12), p. 100613-
    Details
    In: Weather and Climate Extremes, Elsevier BV, Vol. 42 ( 2023-12), p. 100613-
    Type of Medium: Online Resource
    ISSN: 2212-0947
    URL: Article
    DOI: 10.1016/j.wace.2023.100613
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 2732464-3
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  • 10
    Online Resource
    Online Resource
    Probabilistic projections of El Niño Southern Oscillation properties accounting for model dependence and skill
    Springer Science and Business Media LLC ; 2022
    In:  Scientific Reports Vol. 12, No. 1 ( 2022-12-22)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 12, No. 1 ( 2022-12-22)
    Abstract: The El Niño – Southern Oscillation (ENSO) is a dominant mode of global climate variability. Nevertheless, future multi-model probabilistic projections of ENSO properties have not yet been made. Main roadblocks that have been hindering making these projections are climate model dependence and difficulty in quantifying historical model performance. Dependence is broadly defined as similarity between climate model output, assumptions, or physical parameterizations. Here, we propose a unifying metric of relative model performance, based on the probability density function (PDF) of ENSO paths. This metric is applied to assess the overall skill of Climate Model Intercomparison Project phase 6 (CMIP6) climate models at capturing ENSO. We then perform future multi-model probabilistic projections of changes in ENSO properties (from years 1850–1949 to 2040–2099) under the shared socioeconomic pathway scenario SSP585, accounting for model skill and dependence. We find that future ENSO will likely be more seasonally locked (89% chance), and have a longer period (67% chance). Yet, the jury is still out on future ENSO amplification. Our method reduces uncertainty by up to 37% compared to a simple approach ignoring model dependence and skill.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-022-26513-3
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2615211-3
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