Volume 17 Issue 7, July 2024

Surface meltwater plays a key role in ice shelf stability, and consequently, Antarctica’s sea level contributions. New satellite observations suggest there is substantially more surface meltwater than previously thought, and models are underestimating it.

The fate of water carried by subducted slabs to the deep Earth remains unclear. Experiments suggest that water is unlikely to escape the slabs when they reach the core–mantle boundary despite high pressures and temperatures.

Simple silica exists in many forms on Earth, as Falko Langenhorst explains. Some of these polymorphs can shed light on the Earth’s violent past.

Chemical regimes of atmospheric secondary inorganic aerosol formation and nitrogen deposition in rural areas of the USA shifted from ammonia-sensitive to ammonia-insensitive between 2011 and 2020, according to analyses of long-term observations. These regime shifts led to a reduction in ammonium in aerosols and increased ammonia deposition near emission hotspots.

Climate models and paleoclimate proxy records indicate that the absence of preserved eastern Mediterranean organic-rich layers preceding mid-Pliocene glaciation is linked to a pan-North African humid period caused by a more northerly African monsoon front relative to subsequent glacials. The vegetation expansion caused by this humid phase might have influenced early hominin dispersal.

High-resolution numerical simulations show that subduction of the Indian plate peeled off the mantle lithosphere from the Tibetan Plateau. This process successfully explains first-order observations of the stepwise growth of the plateau, the migration of magmatism in the region and its seismic properties.

Folding-related brittle deformation structures in accretionary wedges may contribute to shallow seismicity in subduction zones, according to a compilation of structural evidence.

High-resolution spacecraft imagery has revealed transient deposits that appear in the early mornings of cold seasons at the high altitudes of the Tharsis volcanoes on Mars, consistent with water frost of atmospheric origin.

Chemical regimes of atmospheric secondary inorganic aerosol formation in rural areas of the United States shifted from NH₃-sensitive to NH₃-insensitive between 2011 and 2020, according to analyses of long-term observational data on aerosol composition and gaseous precursors.

Analysis of satellite imagery suggests that slush accounts for approximately half of the total meltwater area across Antarctic ice shelves.

Modelling results suggest that ice sheets may be more vulnerable to ocean water intrusion at the grounding zone than previously thought due to a potential tipping point that leads to runaway melting.

Extreme and highly variable summer floods in the Nile River valley through the North African Humid Period were modulated by both interannual and multi-decadal climate modes, according to an offshore sedimentary archive.

Substantial evolution of the Nile River over the past 11,500 years, shaping the riverine landscape and ancient Egyptian culture, is linked to climate and environmental changes, according to analyses of sediment cores near Luxor dated with optically stimulated luminescence.

Millennial-scale trends in cosmogenic radionuclide production rates through the Holocene are largely the result of variations in geomagnetic field and not solar activity, according to an analysis of several radionuclide records and geomagnetic field models.

An absence of sapropels in eastern Mediterranean sediments suggests an expansion of vegetation over a relatively humid North African landscape preceding the mid-Pliocene glaciation, potentially facilitating early human migration.

Oxygen in shallow shelf waters rose linearly with atmospheric oxygen in the Neoproterozoic era, potentially driving the first radiation of marine animals, but widespread ocean oxygenation came later, according to reconstructions of oxygen levels and marine productivity.

Climate simulations suggest atmospheric tides in resonance with atmospheric waves on early Earth when days were shorter could have modified tropical convection patterns and warmed the planet despite a fainter Sun.

Delamination of the lithospheric mantle from the overriding Eurasian plate below the Tibetan Plateau is consistent with topographic, magmatic and seismic observations, according to numerical simulations of the geodynamic evolution of the plateau.

The intermediate-scale Kamchatka thermochemical anomaly segregated from the Perm anomaly and may have generated a mantle plume before merging with the Pacific large low-velocity province, according to a study of mantle tomographic and numerical models.

Water-bearing subducted slabs may not dehydrate and contribute to chemical heterogeneities at the core–mantle boundary, according to high-pressure and high-temperature melting experiments.

Core processes, dynamically linked to mantle and climate-related surface processes, contribute to both the long-term trend and shorter-term fluctuations observed in Earth’s polar motion, according to predictions from physics-informed neural networks.