Evolution of Lunar Orbit under Climate Dynamics since the Last Glacial Cycle

In this paper, we present the consistent evolution of short-period exoplanets coupling the tidal and gravothermal evolution of the planet. Contrarily to previous similar studies, our calculations are based on the complete tidal evolution equations of the Hut model, valid at any order in eccentricity, obliquity and spin. We demonstrate, both analytically and numerically, that, except if the system was formed with a nearly circular orbit (e<0.2), solving consistently the complete tidal equations is mandatory to derive correct tidal evolution histories. We show that calculations based on tidal models truncated at second order in eccentricity, as done in all previous studies, lead to erroneous tidal evolutions. As a consequence, tidal energy dissipation rates are severely underestimated in all these calculations and the characteristic timescales for the various orbital parameters evolutions can be wrong by up to three orders in magnitude. Based on these complete, consistent calculations, we revisit the viability of the tidal heating hypothesis to explain the anomalously large radius of transiting giant planets. We show that, even though tidal dissipation does provide a substantial contribution to the planet's heat budget and can explain some of the moderately bloated hot-Jupiters, this mechanism can not explain alone the properties of the most inflated objects, including HD 209458b. Indeed, solving the complete tidal equations shows that enhanced tidal dissipation and thus orbit circularization occur too early during the planet's evolution to provide enough extra energy at the present epoch. In that case another mechanisms, such as stellar irradiation induced surface winds dissipating in the planet's tidal bulges, or inefficient convection in the planet's interior must be invoked, together with tidal dissipation, to provide all the pieces of the abnormally large exoplanet puzzle.

At present, tides supply approximately half (1 TW) of the energy necessary to sustain the global deep meridional overturning circulation (MOC) through diapycnal mixing. During the Last Glacial Maximum (LGM; 19,000–26,500 years BP), tidal dissipation in the open ocean may have strongly increased due to the 120‐ to 130‐m global mean sea level drop and changes in ocean basin shape. However, few investigations into LGM climate and ocean circulation consider LGM tidal mixing changes. Here, using an intermediate complexity climate model, we present a detailed investigation on how changes in tidal dissipation would affect the global MOC. Present‐day and LGM tidal constituents M2, S2, K1, and O1 are simulated using a tide model and accounting for LGM bathymetric changes. The tide model results suggest that the LGM energy supply to the internal wave field was 1.8–3 times larger than at present and highly sensitive to Antarctic and Laurentide ice sheet extent. Including realistic LGM tide forcing in the LGM climate simulations leads to large increases in Atlantic diapycnal diffusivities and strengthens (by 14–64% at 32°S) and deepens the Atlantic MOC. Increased input of tidal energy leads to a greater drawdown of North Atlantic Deep Water and mixing with Antarctic Bottom Water altering Atlantic temperature and salinity distributions. Our results imply that changes in tidal dissipation need be accounted for in paleoclimate simulation setup as they can lead to large differences in ocean mixing, the global MOC, and presumably also ocean carbon and other biogeochemical cycles.

We study how stably stratified or semi-convective layers alter the tidal dissipation rates associated with the generation of internal waves in planetary interiors. We consider if these layers could contribute to the high rates of tidal dissipation observed for Jupiter and Saturn in our solar system. We use an idealized global spherical Boussinesq model to study the influence of stable stratification and semi-convective layers on tidal dissipation rates. We carry out analytical and numerical calculations considering realistic tidal forcing and measure how the viscous and thermal dissipation rates depend on the parameters relating to the internal stratification profile. We find that the strongly frequency-dependent tidal dissipation rate is highly dependent on the parameters relating to the stable stratification, with strong resonant peaks that align with the internal modes of the system. The locations and sizes of these resonances depend on the form and parameters of the stratification, which we explore both analytically and numerically. Our results suggest that stable stratification can significantly enhance the tidal dissipation in particular frequency ranges. Analytical calculations in the low-frequency regime give us scaling laws for the key parameters, including the tidal quality factor due to internal gravity waves. Stably stratified layers can significantly contribute to tidal dissipation in solar and extrasolar giant planets, and we estimate substantial tidal evolution for hot Neptunes. Further investigation is needed to robustly quantify the significance of the contribution in realistic interior models, and to consider the contribution of inertial waves.

Studies of the Last Glacial Maximum (LGM; 26.5–19 ka) tides showed strong enhancements in open ocean tidal amplitudes and dissipation rates; however, changes prior to the LGM remain largely unexplored. Using two different ice sheet and sea level reconstructions, we explicitly simulate the evolution of the leading semi‐diurnal and diurnal tidal constituents (M2, S2, K1, and O1) over the last glacial cycle with a global tide model. Both sets of simulations show that global changes, dominated by the Atlantic, take place for the semi‐diurnal constituents, while changes for the diurnal constituents are mainly regional. Irrespective of the reconstruction, open ocean dissipation peaks during the sea level lowstands of MIS 2 (∼20 ka) and MIS 4 (∼60 ka), although dissipation values prior to MIS 2 are sensitive to differences in reconstructed ice sheet extent. Using the statistically significant relationship between global mean sea level and dissipation, we apply regression analysis to infer open ocean and shelf dissipation, respectively, over the last four glacial cycles back to 430 ka. Our analysis shows that open ocean tidal energy was probably increased for most of this period, peaking during glacial maxima, and returning to near‐present‐day values during interglacials. Due to tidal resonance during glacial phases, small changes in bathymetry could have caused large changes in tidal amplitudes and dissipation, emphasizing the need for accurate ice margin reconstructions. During glacial phases, once global mean sea level decreased by more than ∼100 m, the amount of open ocean tidal energy available for ocean mixing approximately doubled.

Preface Introduction Victor R. Baker List of contributors. General 1. Oxic, suboxic, and anoxic conditions in the Black Sea James W. Murray, Keith Stewart, Steven Kassakian, Marta Krynytzky, and Doug DiJulio 2. Molluscan paleoecology in the reconstruction of coastal changes Daniela Basso and Cesare Corselli 3. Climate modeling results for the Circum-Pontic Region from the late Pleistocene to the mid-Holocene Alexander V. Kislov and Pavel M. Toropov Principal Flood Scenarios 4. Status of the Black Sea flood hypothesis William B.F. Ryan 5. The Marmara Sea Gateway since ~16 ky BP: non-catastrophic causes of paleoceanographic events in the Black Sea at 8.4 and 7.15 ky BP Richard N. Hiscott, Ali E. Aksu, Peta J. Mudie, Michael A. Kaminski, Teofilo Abrajano, Dogan Yasar, and Andre Rochon 6. The late glacial great flood in the Ponto-Caspian basin Andrei L. Chepalyga 7. Controversy over Noah's Flood in the Black Sea: geological and foraminiferal evidence from the shelf Valentina V. Yanko-Hombach Research in the Northern Sector 8. On the post-glacial changes in the level of the Black Sea Pavel N. Kuprin and Valentin M. Sorokin 9. The post-glacial transgression of the Black Sea Valery I. Shmuratko 10. Climate dynamics, sea-level change, and shoreline migration in the Ukrainian sector of the Circum-Pontic Region Yuri Shuisky 11. The Middle Paleolithic and early Upper Paleolithic in the northern Black Sea region Viktor P. Chabai 12. Environment, sea-level changes, and human migrations in the northern Pontic area during late Pleistocene and Holocene times Pavel M. Dolukhanov and Konstantin K. Shilik 13. HoloceneMediterranization of the southern Crimean vegetation: paleoecological records, regional climate change, and possible non-climatic influences Carlos E. Cordova 14. Pontic-Caspian Mesolithic and Early Neolithic societies at the time of the Black Sea flood: a small audience and small effects David W. Anthony 15. Fluctuations in the level of the Black Sea and Mesolithic settlement of the northern Pontic area Vladimir N. Stanko Research in the Western Sector 16. The northwestern Black Sea: climatic and sea-level changes in the Late Quaternary Nicolae Panin and Irina Popescu 17. Sea-level fluctuations and coastline migration in the northwestern Black Sea area over the last 18 ky based on high-resolution lithological-genetic analysis of sediment architecture Evgeny G. Konikov 18 Water-level fluctuations in the Black Sea since the Last Glacial Maximum Gilles Lericolais, Irina Popescu, Francois Guichard, Speranta-Maria Popescu, and Laurence Manolakakis 19. Archaeological and paleontological evidence of climate dynamics, sea-level change, and coastline migration in the Bulgarian sector of the Circum-Pontic Region Mariana Filipova-Marinova 20. Dendrochronology of submerged Bulgarian sites Peter I. Kuniholm, Maryanne W. Newton, and Bernd Kromer 21. The Neolithization of the north Pontic area and the Balkans in the context of the Black Sea floods Valentin Dergachev and Pavel M. Dolukhanov 22. Holocene changes in the level of the Black Sea: consequences at a human scale Douglass W. Bailey Research in the Southern Sector 23. Morphotectonic development of the southern Black Sea region and the Bosphorus channel Yucel Yilmaz 24. Sea-level changes modified the Quaternary coastlines in the Marmara region,

A key controller of a planet's rotational evolution, and hence habitability, is tidal dissipation, which on Earth is dominated by the ocean tides. Because exoplanet or deep‐time Earth topographies are unknown, a statistical ensemble is used to constrain possible tidal dissipation rates on an Earth‐like planet. A dedicated tidal model is used together with 120 random continental configurations to simulate Earth's semidiurnal lunar tide. The results show a possible ocean tidal dissipation range spanning 3 orders of magnitude, between 2.3 GWto 1.9 TW (1 TW=1012 W). When model resolution is considered, this compares well with theoretical limits derived for the energetics of Earth's present‐day deep ocean. Consequently, continents exert a fundamental control on tidal dissipation rates and we suggest that plate tectonics on a planet will induce a time‐varying dissipation analogous to Earth's. This will alter rotational periods over millions of years and further complicate the role of tides for planetary evolution.

&amp;lt;p&amp;gt;Simulations of the tides from the Last Glacial Maximum (26.5 &amp;amp;#8211; 19 kyr BP) to the present show large amplitude and dissipation changes, especially in the semi-diurnal band during the deglacial period. New reconstructions of global ice sheet history and sea levels allow us to extend the tidal simulations back to cover most of the last glacial cycle. Climate during this period was far from stable with periods of ice sheet advance and lower sea levels interspaced with ice sheet melting and sea level increases. Here, using the sea level and ice history from Gowan et al., 2021, we present simulations of tidal amplitudes and dissipation from 80 kyr BP to present using the tide model OTIS. Our results show large variations in amplitudes and dissipation over this period for the M&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; tidal constituent with several tidal maxima. Due to the lower sea levels and altered bathymetry open ocean dissipation was enhanced with respect to present day levels for most of the glacial cycle. This result is important in the context of historical ocean mixing rates. For the semi-diurnal K&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt; tide, in contrast, changes are mainly local or regional.&amp;amp;#160;&amp;lt;/p&amp;gt;

The last glacial maximum and late glacial environmental and climate dynamics in the Baikal region inferred from an oxygen isotope record of lacustrine diatom silica

Projections of global sea-level rise into the future have become more pessimistic over the past five years or so. A global rise by more than one metre by the year 2100 is now widely accepted as a serious possibility if greenhouse gas emissions continue unabated. That is witnessed by the scientific assessments that were made since the last IPCC report was published in 2007. The Delta Commission of the Dutch government projected up to 1.10 m as a 'high-end' scenario (Vellinga et al 2009). The Scientific Committee on Antarctic Research (SCAR) projected up to 1.40 m (Scientific Committee on Antarctic Research 2009), and the Arctic Monitoring and Assessment Programme (AMAP) gives a range of 0.90–1.60 m in its 2011 report (Arctic Monitoring and Assessment Programme 2011). And recently the US Army Corps of Engineers recommends using a 'low', an 'intermediate' and a 'high' scenario for global sea-level rise when planning civil works programmes, with the high one corresponding to a 1.50 m rise by 2100 (US Army Corps of Engineers 2011).

Holocene relative sea-level changes inferred from multiple proxies on the west coast of South Korea

Surficial shell accumulations from shallow marine settings are typically averaged over centennial-to-millennial time scales and dominated by specimens that died in the most recent centuries, resulting in strongly right-skewed age-frequency distributions (AFDs). However, AFDs from modern offshore settings (outer shelf and uppermost continental slope) still need to be explored. Using individually dated shells (14C-calibrated amino acid racemization), we compared AFDs along an onshore-offshore gradient across the southern Brazilian shelf, with sites ranging from the inner shelf, shallow-water (&amp;lt; 40 m) to offshore, deep-water (&amp;gt; 100 m) settings. The duration of time averaging is slightly higher in deeper water environments, and the AFD shapes change along the depositional profile. The inner shelf AFDs are strongly right-skewed due to the dominance of shells from the most recent millennia (median age range: 0–3 ka). In contrast, on the outer shelf and the uppermost continental slope, AFDs are symmetrical to left-skewed and dominated by specimens that died following the Last Glacial Maximum (median age range: 15–18 ka). The onshore-offshore changes in the observed properties of AFDs—increased median age and decreased skewness, but only slightly increased temporal mixing—likely reflect changes in sea level and concurrent water depth-related changes in biological productivity. These results suggest that on a passive continental margin subject to post-glacial sea-level changes, the magnitude of time-averaging of shell assemblages is less variable along the depositional profile than shell assemblage ages and the shapes of AFDs.

Residual circulation in the English Channel as a dynamically consistent synthesis of shore-based observations of sea level and currents

Improving tidal modeling for rocky worlds

Driving mechanisms of Holocene coastal evolution in the Bonifacio Strait (Western Mediterranean)

Context. Tidal dissipation in planets and in stars is one of the key physical\nmechanisms that drive the evolution of planetary systems.\n Aims. Tidal dissipation properties are intrisically linked to the internal\nstructure and the rheology of studied celestial bodies. The resulting\ndependence of the dissipation upon the tidal frequency is strongly different in\nthe cases of solids and fluids.\n Methods. We compute the tidal evolution of a two-body coplanar system, using\nthe tidal quality factor's frequency-dependencies appropriate to rocks and to\nconvective fluids.\n Results. The ensuing orbital dynamics comes out smooth or strongly erratic,\ndependent on how the tidal dissipation depends upon frequency.\n Conclusions. We demonstrate the strong impact of the internal structure and\nof the rheology of the central body on the orbital evolution of the tidal\nperturber. A smooth frequency-dependence of the tidal dissipation renders a\nsmooth orbital evolution while a peaked dissipation can furnish erratic orbital\nbehaviour.\n