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1. Sea Ice and the Law of the Sea: The Myth of Article 234

   Lynch, Amanda H; Norchi, Charles H (July 2024, Ocean and coastal law journal)

   The sea ice of Article 234 of UNCLOS represents not the physical ice of the Arctic Ocean but a negotiated myth of ice as it affects the Arctic littoral states. The stability of this prescription is threatened by anthropogenic climate change causing a preferential evacuation of ice from the eastern Arctic compared to the western Arctic, as well as expectations for a possible future ice-free Arctic. This is leading to an intensification of claims on marine space. The irreducible uncertainties of the future trajectory of Arctic change demands a dynamic response. The myth of Article 234 will ultimately align with the complexities of the phenomenon of disappearing ice. It is in the dynamic nature of international law that prescriptions do not remain constant and neither does ice. 

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2. Coevolution of Extreme Sea Levels and Sea‐Level Rise Under Global Warming

   https://doi.org/10.1029/2023EF003649  

   Boumis, Georgios; Moftakhari, Hamed R.; Moradkhani, Hamid (July 2023, Earth's Future)

   Abstract Design of coastal defense structures like seawalls and breakwaters can no longer be based on stationarity assumption. In many parts of the world, an anticipated sea‐level rise (SLR) due to climate change will constitute present‐day extreme sea levels inappropriate for future coastal flood risk assessments since it will significantly increase their probability of occurrence. Here, we first show that global annual maxima sea levels (AMSLs) have been increasing in magnitude over the last decades, primarily due to a positive shift in mean sea level (MSL). Then, we apply non‐stationary extreme value theory to model the extremal behavior of sea levels with MSL as a covariate and quantify the evolution of AMSLs in the following decades using revised probabilistic sea‐level rise projections. Our analysis reveals that non‐stationary distributions exhibit distinct differences compared to simply considering stationary conditions with a change in location parameter equal to the amount of MSL rise. With the use of non‐stationary distributions, we show that by the year 2050 many locations will experience their present‐day 100‐yr return level as an event with return period less than 15 and 9 years under the moderate (RCP4.5) and high (RCP8.5) representative concentration pathways. Also, we find that by the end of this century almost all locations examined will encounter their current 100‐yr return level on an annual basis, even if CO₂concentration is kept at moderate levels (RCP4.5). Our assessment accounts for large uncertainty by incorporating ambiguities in both SLR projections and non‐stationary extreme value distribution parameters via a Monte Carlo simulation. 

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3. Sensitivity of Sea‐Surface Enthalpy and Momentum Fluxes to Sea Spray Microphysics

   https://doi.org/10.1029/2021JC017774  

   Sroka, Sydney; Emanuel, Kerry (December 2021, Journal of Geophysical Research: Oceans)

   Abstract Accurate estimates of air‐sea enthalpy and momentum fluxes are critically important for hurricane intensity predictions. However, calculating these fluxes is challenging due to the nature of the air‐sea transition region. At extreme wind speeds, a substantial amount of sea spray is lofted making it necessary to calculate the sea spray‐mediated enthalpy and momentum fluxes. These calculations rely on microphysical equations, which are sensitive to the details of the local environmental conditions. Here we use a microphysical model to show that there exists a threshold wind speed beyond which the net sea spray‐mediated enthalpy and momentum fluxes are well‐approximated by using the net sea spray mass flux alone. This result supports the hypothesis that at extreme wind speeds, the ratio of the air‐sea exchange coefficients becomes independent of wind speed, implying the air‐sea flux calculations can be substantially simplified. 

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4. How Sea Ice Drift Influences Sea Ice Area and Volume

   https://doi.org/10.1029/2021GL093069  

   Wagner, T. J.; Eisenman, I.; Mason, H. C. (October 2021, Geophysical Research Letters)

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5. Monthly Sea Surface Temperature, Sea Ice, and Sea Level Pressure over 1850–2023 from Coupled Data Assimilation

   https://doi.org/10.1175/JCLI-D-25-0021.1  

   Cooper, Vincent_T; Hakim, Gregory_J; Armour, Kyle_C (October 2025, Journal of Climate)

   Abstract Historical observations of Earth’s climate underpin our knowledge and predictions of climate variability and change. However, the observations are incomplete and uncertain, and existing datasets based on these observations typically do not assimilate observations simultaneously across different components of the climate system, yielding inconsistencies that limit understanding of coupled climate dynamics. Here, we use coupled data assimilation, which synthesizes observational and dynamical constraints across all climate fields simultaneously, to reconstruct globally resolved sea surface temperature (SST), near-surface air temperature (T), sea level pressure (SLP), and sea ice concentration (SIC), over 1850–2023. We use a Kalman filter and forecasts from an efficient emulator, the linear inverse model (LIM), to assimilate observations of SST, landT, marine SLP, and satellite-era SIC. We account for model error by training LIMs on eight CMIP6 models, and we use the LIMs to generate eight independent reanalyses with 200 ensemble members, yielding 1600 total members. Key findings in the tropics include post-1980 trends in the Walker circulation that are consistent with past variability, whereas the tropical SST contrast (the difference between warmer and colder SSTs) shows a distinct strengthening since 1975. El Niño–Southern Oscillation (ENSO) amplitude exhibits substantial low-frequency variability and a local maximum in variance over 1875–1910. In polar regions, we find a muted cooling trend in the Southern Ocean post-1980 and substantial uncertainty. Changes in Antarctic sea ice are relatively small between 1850 and 2000, while Arctic sea ice declines by 0.5 ± 0.1 (1σ) million km²during the 1920s. Significance StatementThe key advance in our reconstruction is that the ocean, atmosphere, and sea ice are dynamically consistent with each other and with observations across all components, thus forming a true climate reanalysis. Existing climate datasets are typically derived separately for each component (e.g., atmosphere, ocean, and sea ice), leading to spurious trends and inconsistencies in coupled climate variability. We use coupled data assimilation to unify observations and coupled dynamics across components. We combine forecasts from climate models with observations from ocean vessels and weather stations to produce monthly state estimates spanning 1850–2023 and a novel quantification of globally resolved uncertainty. This reconstruction provides insights into historical variability and trends while motivating future efforts to reduce uncertainties in the climate record. 

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