EGU Letters 

This study investigates interactions between soil organic carbon (SOC) and calcium (Ca). It reveals that Ca contributes to SOC stability even in acidic soils, a finding that departs from previous assumptions that Ca's role is limited to neutral or alkaline soils. It also investigates the formation mechanisms driving the association of Ca with a characteristic fraction of SOC, highlighting the importance of decomposition processes in its formation. In this work, the authors employ advanced spectromicroscopy and targeted experiments to confirm that Ca binds SOC compounds rich in aromatic and phenolic groups after decomposition, preventing their loss as dissolved organic carbon. The identification of this biogeochemical mechanism has direct implications for improving soil carbon models and guiding Ca amendment practices in agriculture, enhancing soil carbon retention and contributing to climate resilience.

This letter aims to synergistically combine multifractals and climate network theory to better understand geophysical processes. Multifractals quantify their own variability and intermittency across a wide range of scales, while climate networks reveal their own long-range nonlinear dependencies at the observational scale. This novel methodology is introduced in the context of the Indian Monsoon, highlighting the multifractality of climate networks and showing how to upscale them.

This research letter presents a conceptual model and data from physical experiments for a new mechanism of sediment entrainment on the seafloor during the huge co-seismic motion imposed by the large subduction earthquakes. This new mechanism introduces the concept of sediment entrainment being due to the motion of the sediment bed instead caused my movement of the water above. Furthermore, by identifying the sedimentary fingerprint of megathrust ruptures with high tsunamigenic potential, the authors propose a new approach to constraining the seismic and tsunami hazard in subduction zones.

The ocean plays a key role in the global carbon cycle and its carbon sink strength is critical for removing atmospheric carbon dioxide and stabilizing global climate. This oceanic carbon sink strength is difficult to measure and models provide estimates that differ from one another. Terhaar combines multiple modeling approaches using composite model-based averages and fully coupled Earth System Models to take advantages of the benefits of both, and in doing so derives a similar sink strength to existing estimates but with reduced uncertainty.

The explosive Hunga Tonga eruption in 2022 had several characteristics that are unique in the recent observational record. Its effects on the atmosphere are of great scientific interest and have included rapidly propagating patterns of Lamb and gravity waves and long-lived anomalies in stratospheric water vapour. This modelling study demonstrates how, through a coupled sequence of chemical, radiative and dynamical mechanisms, the additional water vapour in the tropical upper stratosphere is likely to have had a significant effect on the wintertime circulation of the stratosphere and hence the troposphere in Northern Hemisphere mid- and high latitudes. These results on the fascinating Hunga Tonga event have wider relevance to perturbations of the climate system where the initial impact is stratospheric but important secondary effects are felt elsewhere, including at the surface.