The bulk properties of iron at the pressure and temperature conditions of Earth's core were determined by a method that combines first-principles and classical molecular dynamic simulations. The theory indicates that (i) the iron melting temperature at inner-core boundary (ICB) pressure (330 gigapascals) is 5400 (+/-400) kelvin; (ii) liquid iron at ICB conditions is about 6% denser than Earth's outer core; and (iii) the shear modulus of solid iron close to its melting line is 140 gigapascals, consistent with the seismic value for the inner core. These results reconcile melting temperature estimates based on sound velocity shock wave data with those based on diamond anvil cell experiments.
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http://dx.doi.org/10.1126/science.287.5455.1027 | DOI Listing |
Environ Monit Assess
January 2025
Institute of Geoecology and Geoinformation, Adam Mickiewicz University, Poznań, Poland.
A spatial assessment of temporal forest cover changes is essential for effective forest conservation and management practices. This study analyzes changes in forest cover and the evolution of forest spatial configuration using Landsat satellite imagery over the past three decades (1990-2020) in Azad Jammu and Kashmir (AJK), Pakistan. To achieve the objectives, landscape metrics and forest fragmentation analyses were applied.
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January 2025
Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand.
The fate of the West Antarctic Ice Sheet (WAIS) is the largest cause of uncertainty in long-term sea-level projections. In the last interglacial (LIG) around 125,000 years ago, data suggest that sea level was several metres higher than today, and required a significant contribution from Antarctic ice loss, with WAIS usually implicated. Antarctica and the Southern Ocean were warmer than today, by amounts comparable to those expected by 2100 under moderate to high future warming scenarios.
View Article and Find Full Text PDFSci Adv
January 2025
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
Ice core measurements reveal dipole-like snow accumulation trends over West Antarctica throughout the 20th century, with an increase of >2000 billion metric tons over the Antarctic Peninsula and Ellsworth Land but a decrease of ~500 billion metric tons over Marie Byrd Land. Although atmospheric teleconnections were frequently revealed, linking variability between tropics and higher latitudes on interannual and decadal timescales, centennial-scale teleconnection is absent from literature. Here, using statistical analysis and numerical experiments, we reveal that changes of tropical oceans throughout the 20th century drive the long-term Antarctic snowfall trend.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
Department of Earth Sciences, University College London, London WC1E 6BT, United Kingdom.
CaSiO[Formula: see text] perovskite (CaPv) is the last major mineral in the Earth's lower mantle whose elasticity remains largely unresolved. Here, we investigate the elasticity of CaPv using ab initio machine-learning force fields (MLFF). At room temperature, the elasticity of tetragonal CaPv determined by MLFF molecular dynamics (MD) agrees well with experimental measurements after considering temperature induced variations in the hydrostatic structure, proving the effectiveness of the method.
View Article and Find Full Text PDFEnergy Fuels
January 2025
Geothermal Energy and Geofluids Group, Institute of Geophysics, Department of Earth and Planetary Sciences, ETH Zurich, Zurich 8092, Switzerland.
Carbon capture and storage (CCS) and CO-based geothermal energy are promising technologies for reducing CO emissions and mitigating climate change. Safe implementation of these technologies requires an understanding of how CO interacts with fluids and rocks at depth, particularly under elevated pressure and temperature. While CO-bearing aqueous solutions in geological reservoirs have been extensively studied, the chemical behavior of water-bearing supercritical CO remains largely overlooked by academics and practitioners alike.
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