United Nations: Paris Agreement. In United Nations Treaty Series Vol. 3156, 79 (United Nations, 2015).

IPCC Climate Change 2023: Synthesis Report (eds Core Writing Team, Lee, H. & Romero, J.) 35–115 (IPCC, 2023); https://doi.org/10.59327/IPCC/AR6-9789291691647

Armstrong McKay, D. I. et al. Exceeding 1.5°C global warming could trigger multiple climate tipping points. Science 377, 7950 (2022).

Article 

Google Scholar
 

Wunderling, N. et al. Climate tipping point interactions and cascades: a review. Earth Syst. Dyn. 15, 41–74 (2024).

Article 

Google Scholar
 

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

Article 
CAS 

Google Scholar
 

Caldeira, K. & Wickett, M. E. Anthropogenic carbon and ocean pH. Nature 425, 365–365 (2003).

Article 
CAS 

Google Scholar
 

Doney, S. C., Fabry, V. J., Feely, R. A. & Kleypas, J. A. Ocean acidification the other CO2 problem. Annu. Rev. Marine Sci. 1, 169–192 (2009).

Article 

Google Scholar
 

Jiang, L.-Q. et al. Global surface ocean acidification indicators from 1750 to 2100. J. Adv. Model. Earth Syst. 15, 2022–003563 (2023).

Article 

Google Scholar
 

Müller, J. D. & Gruber, N. Progression of ocean interior acidification over the industrial era. Sci. Adv. 10, 3103 (2024).

Article 

Google Scholar
 

Mathesius, S., Hofmann, M., Caldeira, K. & Schellnhuber, H. J. Long-term response of oceans to CO2 removal from the atmosphere. Nat. Clim. Change 5, 1107–1113 (2015).

Article 
CAS 

Google Scholar
 

Collins, M. et al. in IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (eds Pörtner, H.-O. et al) 589–655 (Cambridge Univ. Press, 2019).

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).

Article 

Google Scholar
 

Koven, C. D. et al. Multi-century dynamics of the climate and carbon cycle under both high and net negative emissions scenarios. Earth Syst. Dyn. 13, 885–909 (2022).

Article 

Google Scholar
 

Yao, W., Cao, L. & Jin, X. Simulated responses of the ocean carbon cycle to different rates of atmospheric CO2 removal. J. Geophys. Res. Oceans 130, 2024–022115 (2025).

Article 

Google Scholar
 

Resplandy, L., Bopp, L., Orr, J. C. & Dunne, J. P. Role of mode and intermediate waters in future ocean acidification: analysis of CMIP5 models. Geophys. Res. Lett. 40, 3091–3095 (2013).

Article 

Google Scholar
 

Jones, D. C., Ito, T., Takano, Y. & Hsu, W.-C. Spatial and seasonal variability of the air–sea equilibration timescale of carbon dioxide. Glob. Biogeochem. Cycles 28, 1163–1178 (2014).

Article 
CAS 

Google Scholar
 

Bates, N. R., Moran, S. B., Hansell, D. A. & Mathis, J. T. An increasing CO2 sink in the Arctic Ocean due to sea-ice loss. Geophys. Res. Lett. 33, 2006–027028 (2006).

Article 

Google Scholar
 

Bopp, L. et al. Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models. Biogeosciences 10, 6225–6245 (2013).

Article 

Google Scholar
 

Qi, D. et al. Climate change drives rapid decadal acidification in the Arctic Ocean from 1994 to 2020. Science 377, 1544–1550 (2022).

Article 
CAS 

Google Scholar
 

Yasunaka, S. et al. An assessment of CO2 uptake in the Arctic Ocean from 1985 to 2018. Glob. Biogeochem. Cycles 37, 2023–007806 (2023).

Article 

Google Scholar
 

Terhaar, J., Orr, J. C., Gehlen, M., Ethé, C. & Bopp, L. Model constraints on the anthropogenic carbon budget of the Arctic Ocean. Biogeosciences 16, 2343–2367 (2019).

Article 
CAS 

Google Scholar
 

Köhl, A. & Serra, N. Causes of decadal changes of the freshwater content in the Arctic Ocean. J. Clim. 27, 3461–3475 (2014).

Article 

Google Scholar
 

Shu, Q., Qiao, F., Song, Z., Zhao, J. & Li, X. Projected freshening of the Arctic Ocean in the 21st century. J. Geophys. Res. Oceans 123, 9232–9244 (2018).

Article 

Google Scholar
 

Terhaar, J., Torres, O., Bourgeois, T. & Kwiatkowski, L. Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble. Biogeosciences 18, 2221–2240 (2021).

Article 
CAS 

Google Scholar
 

Steinacher, M., Joos, F., Frölicher, T. L., Plattner, G.-K. & Doney, S. C. Imminent ocean acidification in the Arctic projected with the NCAR global coupled carbon cycle-climate model. Biogeosciences 6, 515–533 (2009).

Article 
CAS 

Google Scholar
 

Orr, J. C. et al. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437, 681–686 (2005).

Article 
CAS 

Google Scholar
 

Fabry, V. J., Seibel, B. A., Feely, R. A. & Orr, J. C. Impacts of ocean acidification on marine fauna and ecosystem processes. ICES J. Mar. Sci. 65, 414–432 (2008).

Article 
CAS 

Google Scholar
 

Kwiatkowski, L. & Orr, J. C. Diverging seasonal extremes for ocean acidification during the twenty-first century. Nat. Clim. Change 8, 141–145 (2018).

Article 
CAS 

Google Scholar
 

Orr, J. C., Kwiatkowski, L. & Pörtner, H.-O. Arctic Ocean annual high in pCO2 could shift from winter to summer. Nature 610, 94–100 (2022).

Article 
CAS 

Google Scholar
 

Yamamoto-Kawai, M., McLaughlin, F. A., Carmack, E. C., Nishino, S. & Shimada, K. Aragonite undersaturation in the Arctic Ocean: effects of ocean acidification and sea ice melt. Science 326, 1098–1100 (2009).

Article 
CAS 

Google Scholar
 

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).

Article 
CAS 

Google Scholar
 

Jiang, J. et al. Response of ocean acidification to atmospheric carbon dioxide removal. J. Environ. Sci. 140, 79–90 (2024).

Article 
CAS 

Google Scholar
 

Timmermans, M.-L. & Marshall, J. Understanding Arctic Ocean circulation: a review of ocean dynamics in a changing climate. J. Geophys. Res. Oceans 125, 2018–014378 (2020).

Article 

Google Scholar
 

Yu, H. et al. Incomplete Arctic sea-ice recovery under CO2 removal and its effects on the winter atmospheric circulation. Geophys. Res. Lett. 52, 2024–113541 (2025).

Article 

Google Scholar
 

Manizza, M. et al. Changes in the Arctic Ocean CO2 sink (1996–2007): a regional model analysis. Glob. Biogeochem. Cycles 27, 1108–1118 (2013).

Article 
CAS 

Google Scholar
 

MacGilchrist, G. A. et al. The Arctic Ocean carbon sink. Deep Sea Res. Part I 86, 39–55 (2014).

Article 
CAS 

Google Scholar
 

Ouyang, Z. et al. Sea-ice loss amplifies summertime decadal CO2 increase in the western Arctic Ocean. Nat. Clim. Change 10, 678–684 (2020).

Article 
CAS 

Google Scholar
 

Sanderson, B. M. et al. The need for carbon-emissions-driven climate projections in CMIP7. Geosci. Model Dev. 17, 8141–8172 (2024).

Article 
CAS 

Google Scholar
 

Elson, P. et al. SciTools/cartopy: v0.22.0. Zenodo https://doi.org/10.5281/zenodo.8216315 (2023).

Ziehn, T. et al. The Australian Earth System Model ACCESS-ESM1.5. J. South. Hemisph. Earth Syst. Sci. 70, 193–214 (2020).

Article 

Google Scholar
 

Swart, N. C. et al. The Canadian Earth System Model version 5 (CanESM5.0.3). Geosci. Model Dev. 12, 4823–4873 (2019).

Article 
CAS 

Google Scholar
 

Danabasoglu, G. et al. The Community Earth System Model Version 2 (CESM2). J. Adv. Model. Earth Syst. 12, 2019–001916 (2020).

Article 

Google Scholar
 

Séférian, R. et al. Evaluation of CNRM Earth System Model, CNRM-ESM2-1: role of Earth system processes in present-day and future climate. J. Adv. Model. Earth Syst. 11, 4182–4227 (2019).

Article 

Google Scholar
 

Dunne, J. P. et al. The GFDL Earth System Model Version 4.1 (GFDL-ESM 4.1): overall coupled model description and simulation characteristics. J. Adv. Model. Earth Syst. 12, 2019–002015 (2020).

Article 

Google Scholar
 

Hajima, T. et al. Development of the MIROC-ES2L Earth system model and the evaluation of biogeochemical processes and feedbacks. Geosci. Model Dev. 13, 2197–2244 (2020).

Article 

Google Scholar
 

Seland, Ø et al. Overview of the Norwegian Earth System Model (NorESM2) and key climate response of CMIP6 DECK, historical, and scenario simulations. Geosci. Model Dev. 13, 6165–6200 (2020).

Article 
CAS 

Google Scholar
 

Sellar, A. A. et al. UKESM1 description and evaluation of the U.K. Earth system model. J. Adv. Model. Earth Syst. 11, 4513–4558 (2019).

Article 

Google Scholar
 

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).

Article 

Google Scholar
 

Orr, J. C. & Epitalon, J.-M. Improved routines to model the ocean carbonate system: Mocsy 2.0. Geosci. Model Dev. 8, 485–499 (2015).

Article 

Google Scholar
 

Garcia, H. E. et al. World Ocean Atlas 2023, Volume 4: Dissolved Inorganic Nutrients (Phosphate, Nitrate and Nitrate+Nitrite, Silicate) (NOAA, 2024).

Waters, J., Millero, F. J. & Woosley, R. J. Corrigendum to “The free proton concentration scale for seawater pH”, [MARCHE 149 (2013) 8–22]. Mar. Chem. 165, 66–67 (2014).

Article 
CAS 

Google Scholar
 

Dickson, A. G. & Riley, J. P. The estimation of acid dissociation constants in seawater media from potentionmetric titrations with strong base. I. The ionic product of water — Kw. Mar. Chem. 7, 89–99 (1979).

Article 
CAS 

Google Scholar
 

Uppström, L. R. The boron/chlorinity ratio of deep-sea water from the Pacific Ocean. Deep Sea Res. Oceanogr. Abstr. 21, 161–162 (1974).

Article 

Google Scholar
 

Humphreys, M. P., Lewis, E. R., Sharp, J. D. & Pierrot, D. PyCO2SYS v1.8: marine carbonate system calculations in Python. Geosci. Model Dev. 15, 15–43 (2022).

Article 
CAS 

Google Scholar
 

Kim, S.-K. et al. Widespread irreversible changes in surface temperature and precipitation in response to CO2 forcing. Nat. Clim. Change 12, 834–840 (2022).

Article 
CAS 

Google Scholar
 

Takahashi, T., Olafsson, J., Goddard, J. G., Chipman, D. W. & Sutherland, S. C. Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: a comparative study. Glob. Biogeochem. Cycles 7, 843–878 (1993).

Article 
CAS 

Google Scholar
 

Sarmiento, J. L. & Gruber, N. Ocean Biogeochemical Dynamics (Princeton Univ. Press, 2006).

Orr, J. C., Epitalon, J.-M., Dickson, A. G. & Gattuso, J.-P. Routine uncertainty propagation for the marine carbon dioxide system. Mar. Chem. 207, 84–107 (2018).

Article 
CAS 

Google Scholar
 

Keeling, C. D., Brix, H. & Gruber, N. Interannual variability of the upper ocean carbon cycle at station ALOHA near Hawaii. Glob. Biogeochem. Cycles 18, GB4006 (2004).

Article 

Google Scholar
 

Lovenduski, N. S., Gruber, N., Doney, S. C. & Lima, I. D. Enhanced CO2 outgassing in the Southern Ocean from a positive phase of the Southern Annular Mode. Glob. Biogeochem. Cycles 21, GB2026 (2007).

Article 

Google Scholar
 

Köhn, E. E. Eikekoehn/Arctic_acidification_reversibility_scripts: 1.1. Zenodo https://doi.org/10.5281/zenodo.17415103 (2026).