Biotic gas generation from the degradation of organic carbon in marine sediments supplies and maintains gas hydrates throughout the world’s oceans. In nascent, ultraslow-spreading ocean basins, methane generation can also be abiotic, occurring during the high-temperature (>200 °C) serpentinization of ultramafic rocks. Here, we report on the evolution of a growing Arctic gas- and gas hydrate–charged ...

The development of various combinative methods for Arctic sea ice reconstruction using the sympagic highly-branched isoprenoid (HBI) IP₂₅ in conjunction with pelagic biomarkers has often facilitated more detailed descriptions of sea ice conditions than using IP₂₅ alone. Here, we investigated the application of the Phytoplankton-IP₂₅ index (PIP₂₅) and a ...

The discovery of IP25 as a qualitative biomarker proxy for Arctic sea ice and subsequent introduction of the so-called PIP25 index for semi-quantitative descriptions of sea ice conditions has significantly advanced our understanding of long-term paleo Arctic sea ice conditions over the past decade. We investigated the potential for classification tree1 (CT) models to provide a further approach ...

As the title of the correspondence by Fossen et al. suggests, determining the age of landscape elements of the Earth surface is difficult. We thus welcome the opportunity to clarify our arguments on the contentious themes touched upon by Fredin et al.

Submarine groundwater discharge could impact the transport of critical solutes to the ocean. However, its driver(s), significance over geological time scales, and geographical coverage are poorly understood. We characterize a submarine groundwater seep from the continental slope off northern Norway where substantial amount of meteoric water was detected. We reconstruct the seepage history from ...

Arctic sea ice coverage is shrinking in response to global climate change and summer ice-free conditions in the Arctic Ocean are predicted by the end of the century. The validity of this prediction could potentially be tested through the reconstruction of the climate of the Pliocene epoch (5.33–2.58 million years ago), an analogue of a future warmer Earth. Here we show that, in the Eurasian sector ...

The topographic relief of the Barents Sea was subjected to major changes during the past 1.5 million years mostly due to sediment redistribution driven by glacial activity. This paper addresses the problem of Pleistocene bathymetric evolution of the southern Barents Sea using a numerical modelling approach that considers the influence of regional isostasy on relief development. The model presented ...

The Long chain Diol Index (LDI) is a relatively new organic geochemical proxy for sea surface temperature (SST), based on the abundance of the C₃₀ 1,15-diol relative to the summed abundance of the C₂₈ 1,13-, C₃₀ 1,13- and C₃₀ 1,15-diols. Here we substantially extend and re-evaluate the initial core top calibration by combining the original dataset with 172 ...

Circum-Arctic glacial ice is melting in an unprecedented mode, and release of currently trapped geological methane may act as a positive feedback on ice-sheet retreat during global warming. Evidence for methane release during the penultimate (Eemian, ca. 125 ka) interglacial, a period with less glacial sea ice and higher temperatures than today, is currently absent. Here, we argue that based on ...

Sub-sea Arctic methane and gas hydrate reservoirs are expected to be severely impacted by ocean temperature increase and sea-level rise. Our understanding of the gas emission phenomenon in the Arctic is however partial, especially in deep environments where the access is difficult and hydro-acoustic surveys are sporadic. Here, we report on the first continuous pore-pressure and temperature measurements ...