Reviews & Analysis

Serpentine minerals in Earth's early upper continental crust suppressed atmospheric oxygen levels until the upper crust became granitic.

The careful compilation and interpretation of molybdenum isotopes can track the expansion of sulfidic bottom waters. A synthesis and analysis of data from two Mesozoic ocean anoxic events and the Palaeocene-Eocene thermal maximum applies these techniques to constrain past ocean deoxygenation.

Changes in dust flux, export productivity, and bottom-water oxygenation in the equatorial Pacific Ocean have been tightly linked with variations in North Atlantic climate over the past 100,000 years, according to analyses of marine sediments.

Climate sensitivity, the long-term warming due to doubled atmospheric CO₂ levels, is estimated in the range of 1.5 °C to 4.5 °C. A synthesis of work reveals that whether the value falls at the high or low end, future emissions will have to be strongly limited.

A fast equatorial jet in the Venusian cloud layer has been revealed by the Akatsuki orbiter by tracking cloud movement in near-infrared images. The findings suggest that the Venusian atmosphere is more variable than previously thought.

Microbial metabolisms depend on enzymes that contain trace metals. A synthesis of molecular and geochemical data shows that these metabolic pathways evolved alongside changing marine availability of trace metals during the Precambrian.

The processes that form and recycle continental crust have changed through time. Numerical models reveal an evolution from extensive recycling on early Earth as the lower crust peeled away, to limited recycling via slab break-off today.

Estimates of carbon in the deep mantle vary by more than an order of magnitude. Coupled volcanic CO₂ emission data and magma supply rates reveal a carbon-rich mantle plume source region beneath Hawai'i with 40% more carbon than previous estimates.

Mass changes in High Mountain Asia's glaciers have been under dispute for almost a decade. An analysis of satellite data archives provides an observation-based mass budget for every single glacier in the region.

In our own solar system, Venus is too hot, Mars is too cold and Earth is just right. Simulations show that making an icy planet habitable is not as simple as melting its ice: many icy bodies swing from too cold to too hot, bypassing just right.

River deltas are shaped by interactions between fluvial and tidal processes. Tides act to stabilize delta morphology, but sediment depletion due to human activities disrupts the balance and leads to erosion and scour.

The Sustainable Development Goals map out a broad spectrum of objectives. Analytical tools in form of the Index and Dashboards provide a starting point to set national baselines, and allow comparison of the SDGs with other indices of well-being.

Warm conditions in the Arctic Ocean have been linked to cold mid-latitude winters. Observations and simulations suggest that warm Arctic anomalies lead to a dip in CO₂ uptake capacity in North American ecosystems and to low crop productivity.

Relatively flat, low-relief plateaus contrast with glacially carved, deep fjords. Computational experiments suggest that these astonishing landscapes are formed exclusively by glaciers.

The only temperature profile of the lowermost Venusian atmosphere appears unstable. Compositional heterogeneity due to density-driven separation of N₂ from CO₂ gas in the lower atmosphere of Venus may be a viable explanation.

Phosphorus loading can cause eutrophication of lakes. Analyses of lake chemistry in China reveal that policies have led to lower phosphorus levels overall, but increasing trends in some lakes suggest that expanded policies may be needed.

The North Atlantic region experiences climate variability on a range of timescales. A climate reconstruction suggests that large-magnitude, multidecadal internal variability was a robust feature over the past 1,200 years.

The long-term cooling of Earth's mantle is recorded in the declining temperature and volume of its volcanic outpourings over time. However, analyses of 89-million-year-old lavas from Costa Rica suggest that extremely hot mantle still lurks below.