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Hysteresis of the intertropical convergence zone to CO2 forcing

Abstract

With the unprecedented rate of global warming in recent decades, whether or not anthropogenic climate change is irreversible is an important question. Based on idealized CO2 ramp-up until 1,468 ppm and symmetric ramp-down model experiments, here we show that the intertropical convergence zone (ITCZ) does not respond linearly to CO2 forcing, but exhibits strong hysteresis behaviour. While the location of the ITCZ changes minimally during the ramp-up period, it moves sharply south as soon as CO2 begins to decrease, and its centre eventually resides in the Southern Hemisphere during the ramp-down period. Such ITCZ hysteresis is associated with delays in global energy exchanges between the tropics and extratropics. The delayed energy exchanges are explained by two distinct hysteresis behaviours of the Atlantic Meridional Overturning Circulation and slower warming/cooling in the Southern Ocean. We also suggest that the ITCZ hysteresis can lead to hysteresis in regional hydrological cycles.

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Fig. 1: Evolution and hysteresis of temperature, precipitation and ITCZ location.
Fig. 2: Changes in the global SAT and hydrological cycle.
Fig. 3: Changes in atmospheric meridional energy exchanges.
Fig. 4: Changes in the land hydrological cycle.

Data availability

The data used in this study are available from https://doi.org/10.6084/m9.figshare.1666932461, and the CMIP6 archives are freely available from https://esgf-node.llnl.gov/projects/cmip6.

Code availability

The code used in this study is available from the corresponding author on reasonable request.

References

  1. Joos, F. & Spahni, R. Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years. Proc. Natl Acad. Sci. USA 105, 1425–1430 (2008).

    CAS  Google Scholar 

  2. Swingedouw, D. et al. Early warning from space for a few key tipping points in physical, biological, and social-ecological systems. Surv. Geophys. 41, 1237–1284 (2020).

    Google Scholar 

  3. Lenton, T. M. Early warning of climate tipping points. Nat. Clim. Chang. 1, 201–209 (2011).

    Google Scholar 

  4. Lenton, T. M. et al. Tipping elements in the Earth’s climate system. Proc. Natl Acad. Sci. USA 105, 1786–1793 (2008).

    CAS  Google Scholar 

  5. Miller, G. H. et al. Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks. Geophys. Res. Lett. 39, L02708 (2012).

    Google Scholar 

  6. Broecker, W. S. Unpleasant surprises in the greenhouse? Nature 328, 123–126 (1987).

    CAS  Google Scholar 

  7. Jeltsch-Thömmes, A., Stocker, T. F. & Joos, F. Hysteresis of the Earth system under positive and negative CO2 emissions. Environ. Res. Lett. 15, 124026 (2020).

    Google Scholar 

  8. Wu, P., Wood, R., Ridley, J. & Lowe, J. Temporary acceleration of the hydrological cycle in response to a CO2 rampdown. Geophys. Res. Lett. 37, L12705 (2010).

    Google Scholar 

  9. Sgubin, G., Swingedouw, D., Drijfhout, S., Hagemann, S. & Robertson, E. Multimodel analysis on the response of the AMOC under an increase of radiative forcing and its symmetrical reversal. Clim. Dyn. 45, 1429–1450 (2015).

    Google Scholar 

  10. Cao, L., Bala, G. & Caldeira, K. Why is there a short-term increase in global precipitation in response to diminished CO2 forcing? Geophys. Res. Lett. 38, 1–6 (2011).

    Google Scholar 

  11. Gillett, N. P., Arora, V. K., Zickfeld, K., Marshall, S. J. & Merryfield, W. J. Ongoing climate change following a complete cessation of carbon dioxide emissions. Nat. Geosci. 4, 83–87 (2011).

    CAS  Google Scholar 

  12. Chadwick, R., Wu, P., Good, P. & Andrews, T. Asymmetries in tropical rainfall and circulation patterns in idealised CO2 removal experiments. Clim. Dyn. 40, 295–316 (2013).

    Google Scholar 

  13. Lowe, J. A. et al. How difficult is it to recover from dangerous levels of global warming? Environ. Res. Lett. 4, 014012 (2009).

    Google Scholar 

  14. Frölicher, T. L. & Joos, F. Reversible and irreversible impacts of greenhouse gas emissions in multi-century projections with the NCAR global coupled carbon cycle-climate model. Clim. Dyn. 35, 1439–1459 (2010).

    Google Scholar 

  15. Boucher, O. et al. Reversibility in an Earth system model in response to CO2 concentration changes. Environ. Res. Lett. 7, 024013 (2012).

    Google Scholar 

  16. Wu, P., Ridley, J., Pardaens, A., Levine, R. & Lowe, J. The reversibility of CO2 induced climate change. Clim. Dyn. 45, 745–754 (2015).

    Google Scholar 

  17. Garbe, J., Albrecht, T., Levermann, A., Donges, J. F. & Winkelmann, R. The hysteresis of the Antarctic Ice Sheet. Nature 585, 538–544 (2020).

    CAS  Google Scholar 

  18. Kang, S. M., Shin, Y. & Xie, S. P. Extratropical forcing and tropical rainfall distribution: energetics framework and ocean Ekman advection. npj Clim. Atmos. Sci. 1, 20172 (2018).

    Google Scholar 

  19. Su, H. et al. Tightening of tropical ascent and high clouds key to precipitation change in a warmer climate. Nat. Commun. 8, 1–9 (2017).

    Google Scholar 

  20. Byrne, M. P. & Schneider, T. Atmospheric dynamics feedback: concept, simulations, and climate implications. J. Clim. 31, 3249–3264 (2018).

    Google Scholar 

  21. Kang, S. M., Held, I. M., Frierson, D. M. W. & Zhao, M. The response of the ITCZ to extratropical thermal forcing: idealized slab-ocean experiments with a GCM. J. Clim. 21, 3521–3532 (2008).

    Google Scholar 

  22. Kang, S. M., Frierson, D. M. W. & Held, I. M. The tropical response to extratropical thermal forcing in an idealized GCM: the importance of radiative feedbacks and convective parameterization. J. Atmos. Sci. 66, 2812–2827 (2009).

    Google Scholar 

  23. Frierson, D. M. W. & Hwang, Y. T. Extratropical influence on ITCZ shifts in slab ocean simulations of global warming. J. Clim. 25, 720–733 (2012).

    Google Scholar 

  24. Donohoe, A., Marshall, J., Ferreira, D. & Mcgee, D. The relationship between ITCZ location and cross-equatorial atmospheric heat transport: from the seasonal cycle to the last glacial maximum. J. Clim. 26, 3597–3618 (2013).

    Google Scholar 

  25. Donohoe, A., Marshall, J., Ferreira, D., Armour, K. & Mcgee, D. The interannual variability of tropical precipitation and interhemispheric energy transport. J. Clim. 27, 3377–3392 (2014).

    Google Scholar 

  26. Bischoff, T. & Schneider, T. The equatorial energy balance, ITCZ position, and double-ITCZ bifurcations. J. Clim. 29, 2997–3013 (2016).

    Google Scholar 

  27. Byrne, M. P. & Schneider, T. Narrowing of the ITCZ in a warming climate: physical mechanisms. Geophys. Res. Lett. 43, 11,350–11,357 (2016).

    Google Scholar 

  28. Byrne, M. P. & Schneider, T. Energetic constraints on the width of the intertropical convergence zone. J. Clim. 29, 4709–4721 (2016).

    Google Scholar 

  29. Byrne, M. P., Pendergrass, A. G., Rapp, A. D. & Wodzicki, K. R. Response of the intertropical convergence zone to climate change: location, width, and strength. Curr. Clim. Chang. Rep. 4, 355–370 (2018).

    Google Scholar 

  30. Chou, C., Neelin, J. D., Chen, C. A. & Tu, J. Y. Evaluating the ‘rich-get-richer’ mechanism in tropical precipitation change under global warming. J. Clim. 22, 1982–2005 (2009).

    Google Scholar 

  31. Atwood, A. R., Donohoe, A., Battisti, D. S ., Liu, X. & Pausata, F. S. R. Robust longitudinally variable responses of the ITCZ to a myriad of climate forcings. Geophys. Res. Lett. 47, e2020GL088833 (2020).

    Google Scholar 

  32. Mamalakis, A. et al. Zonally contrasting shifts of the tropical rain belt in response to climate change. Nat. Clim. Chang. 11, 143–151 (2021).

    Google Scholar 

  33. Moreno-Chamarro, E., Marshall, J. & Delworth, T. L. Linking ITCZ migrations to the AMOC and North Atlantic/Pacific SST decadal variability. J. Clim. 33, 893–905 (2020).

    Google Scholar 

  34. Lau, W. K. M. & Kim, K. M. Robust Hadley circulation changes and increasing global dryness due to CO2 warming from CMIP5 model projections. Proc. Natl Acad. Sci. USA 112, 3630–3635 (2015).

    CAS  Google Scholar 

  35. Liu, Z., Vavrus, S., He, F., Wen, N. & Zhong, Y. Rethinking tropical ocean response to global warming: the enhanced equatorial warming. J. Clim. 18, 4684–4700 (2005).

    Google Scholar 

  36. Zhou, W., Xie, S. P. & Yang, D. Enhanced equatorial warming causes deep-tropical contraction and subtropical monsoon shift. Nat. Clim. Chang. 9, 834–839 (2019).

    CAS  Google Scholar 

  37. Lee, S.-Y., Chiang, J. C. H., Matsumoto, K. & Tokos, K. S. Southern Ocean wind response to North Atlantic cooling and the rise in atmospheric CO2: modeling perspective and paleoceanographic implications. Paleoceanography 26, PA1214 (2011).

    Google Scholar 

  38. Liu, W., Fedorov, A. V., Xie, S. P. & Hu, S. Climate impacts of a weakened Atlantic Meridional Overturning Circulation in a warming climate. Sci. Adv. https://doi.org/10.1126/sciadv.aaz4876 (2020).

  39. Cvijanovic, I. & Chiang, J. C. H. Global energy budget changes to high latitude North Atlantic cooling and the tropical ITCZ response. Clim. Dyn. 40, 1435–1452 (2013).

    Google Scholar 

  40. Eyring, V. et al. Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization. Geosci. Model Dev. 9, 1937–1958 (2016).

    Google Scholar 

  41. Schneider, T., Bischoff, T. & Haug, G. H. Migrations and dynamics of the intertropical convergence zone. Nature 513, 45–53 (2014).

    CAS  Google Scholar 

  42. Friedman, A. R., Hwang, Y. T., Chiang, J. C. H. & Frierson, D. M. W. Interhemispheric temperature asymmetry over the twentieth century and in future projections. J. Clim. 26, 5419–5433 (2013).

    Google Scholar 

  43. Chiang, J. C. H. & Bitz, C. M. Influence of high latitude ice cover on the marine intertropical convergence zone. Clim. Dyn. 25, 477–496 (2005).

    Google Scholar 

  44. Bischoff, T. & Schneider, T. Energetic constraints on the position of the intertropical convergence zone. J. Clim. 27, 4937–4951 (2014).

    Google Scholar 

  45. Wei, H. H. & Bordoni, S. Energetic constraints on the ITCZ position in idealized simulations with a seasonal cycle. J. Adv. Model. Earth Syst. 10, 1708–1725 (2018).

    Google Scholar 

  46. White, R. H. et al. Tropical precipitation and cross-equatorial heat transport in response to localized heating: basin and hemisphere dependence. Geophys. Res. Lett. 45, 11,949–11,958 (2018).

    Google Scholar 

  47. Marshall, J., Donohoe, A., Ferreira, D. & McGee, D. The ocean’s role in setting the mean position of the inter-tropical convergence zone. Clim. Dyn. 42, 1967–1979 (2014).

    Google Scholar 

  48. Jackson, L. C. Shutdown and recovery of the AMOC in a coupled global climate model: the role of the advective feedback. Geophys. Res. Lett. 40, 1182–1188 (2013).

    Google Scholar 

  49. Haskins, R. K., Oliver, K. I. C., Jackson, L. C., Wood, R. A. & Drijfhout, S. S. Temperature domination of AMOC weakening due to freshwater hosing in two GCMs. Clim. Dyn. 54, 273–286 (2020).

    Google Scholar 

  50. Levang, S. J. & Schmitt, R. W. What causes the AMOC to weaken in CMIP5? J. Clim. 33, 1535–1545 (2020).

    Google Scholar 

  51. Thorpe, R. B., Gregory, J. M., Johns, T. C., Wood, R. A. & Mitchell, J. F. B. Mechanisms determining the Atlantic Thermohaline Circulation response to greenhouse gas forcing in a non-flux-adjusted coupled climate model. J. Clim. 14, 3102–3116 (2001).

    Google Scholar 

  52. Held, I. M. et al. Probing the fast and slow components of global warming by returning abruptly to preindustrial forcing. J. Clim. 23, 2418–2427 (2010).

    Google Scholar 

  53. Long, S.-M., Xie, S.-P., Zheng, X.-T. & Liu, Q. Fast and slow responses to global warming: sea surface temperature and precipitation patterns. J. Clim. 27, 285–299 (2014).

    Google Scholar 

  54. Hoskins, B. J. & Karoly, D. J. The steady linear response of a spherical atmosphere to thermal and orographic forcing. J. Atmos. Sci. 38, 1179–1196 (1981).

    Google Scholar 

  55. Taylor, K. E., Stouffer, R. J. & Meehl, G. A. An overview of CMIP5 and the experiment design. Bull. Am. Meteorol. Soc. 93, 485–498 (2012).

    Google Scholar 

  56. Hurrell, J. W. et al. The community earth system model: a framework for collaborative research. Bull. Am. Meteorol. Soc. 94, 1339–1360 (2013).

    Google Scholar 

  57. Meinshausen, M. et al. The Shared Socio-economic Pathway (SSP) greenhouse gas concentrations and their extensions to 2500. Geosci. Model Dev. 13, 3571–3605 (2020).

    CAS  Google Scholar 

  58. Keller, D. P. et al. The Carbon Dioxide Removal Model Intercomparison Project (CDRMIP): rationale and experimental protocol for CMIP6. Geosci. Model Dev. 11, 1133–1160 (2018).

    CAS  Google Scholar 

  59. Guo, L. et al. The contributions of local and remote atmospheric moisture fluxes to East Asian precipitation and its variability. Clim. Dyn. 51, 4139–4156 (2018).

    Google Scholar 

  60. Fasullo, J. T. & Trenberth, K. E. The annual cycle of the energy budget. Part I: global mean and land–ocean exchanges. J. Clim. 21, 2297–2312 (2008).

    Google Scholar 

  61. Kug, J.-S. et al. Data for hysteresis of the intertropical convergence zone to CO2 forcing. Figshare https://doi.org/10.6084/m9.figshare.16669324 (2021)

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Acknowledgements

This work was supported by the National Research Foundation of Korea (NRF-2018R1A5A1024958), the National Supercomputing Center with supercomputing resources including technical support (KSC-2018-CHA-0062) and the Korea Research Environment Open NETwork (KREONET).

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Contributions

J.-H.O. compiled the data, conducted analyses, prepared the figures and wrote the manuscript. J.-S.K. designed the research and wrote the majority of the manuscript content. All of the authors discussed the study results and reviewed the manuscript.

Corresponding author

Correspondence to Jong-Seong Kug.

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Peer review information Nature Climate Change thanks Antonios Mamalakis, Didier Swingedouw and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Time evolution of the ITCZ width, northern and southern edge of the ITCZ.

Time series of a, ITCZ width, b, northern edge and c, southern edge of ITCZ. ITCZ edge is defined as the latitude that is changed from a zonal-mean upward motion to a downward motion in the mid-troposphere (700hPa). Lines and shadings as in Fig. 1b.

Extended Data Fig. 2 Precipitation anomalies in the extreme El Niño period.

Composite of DJF averaged precipitation anomalies during 82/83, 97/98, and 15/16 El Niño period in the observational data, b, during the cases when the DJF Nino3.4 index is greater than the 2standard deviation of the DJF Nino3.4 index in the model (CESM1). The observational precipitation data are the Climate Prediction Merged Analysis of Precipitation (CMAP), which uses a horizontal resolution of 2.5° and covers the period from 1979 to 2018. Note that the seasonal cycle and linear trend are removed from the data.

Extended Data Fig. 3 Changes in global hydrological cycle in CMIP6.

Same as Fig. 2c, but the data from the individual models in CMIP6 (ACCESS-ESM1-5, CanESM5, CESM2, GFDL-ESM4, MIROC-ES2L, UKESM1-0-LL).

Extended Data Fig. 4 Changes in global SAT and hydrological cycle in CMIP6.

Same as Fig. 2a and d-e, but the data in the multi-model mean from the CMIP6 (ACCESS-ESM1-5, CanESM5, CESM2, GFDL-ESM4, MIROC-ES2L, UKESM1-0-LL). The regions denoted by the cross-shaped dots a, dots b, and colors c, indicate where more than 2/3 of models disagree a, agree b, and agree c with the sign of the multi-model mean, respectively.

Extended Data Fig. 5 Changes in poleward ocean heat transport.

Time-series of the AMOC strength, global poleward ocean heat transport at 30°N and 30°S, b, poleward ocean heat transport anomalies at 30°N in global, Atlantic, and Indo-Pacific oceans relative to the Year 2000. The ocean heat transport variable (N_HEAT; both global and Atlantic components are included) is obtained directly from the model output. Note that the heat transport at 30°S is the absolute value. Lines and shadings as in Fig. 1b.

Extended Data Fig. 6 Land and ocean contribution to global surface warming.

The percentage of the land and ocean SAT anomalies in the NH and SH for global surface temperature anomaly relative to long-term climatological values of the present climate simulation. Dotted lines represent the ratio of each area to the total earth surface (SH ocean: 40.5%, SH land: 9.5%, NH ocean: 30.2%, NH land: 19.8%). Solid line indicates the boundary of SH land and NH ocean, which represent hemispheric warming contrast. For example, less than 50% of the solid line means that the NH is warmer than the SH. b, The deviation of the percentage of each component from the ratio to the total earth surface (deonted in Dotted lines in a). c, Time-series of the top 2000m ocean heat content anomaly integrated over the Southern Ocean (90°S–50°S) relative to the Year 2000. Lines and shadings as in Fig. 1b.

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Kug, JS., Oh, JH., An, SI. et al. Hysteresis of the intertropical convergence zone to CO2 forcing. Nat. Clim. Chang. 12, 47–53 (2022). https://doi.org/10.1038/s41558-021-01211-6

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