Volume 10 Issue 10, October 2017

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

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.

The release of methane trapped in Martian subsurface reservoirs following planetary obliquity shifts may have contributed to episodic climate warming between 3.6 and 3 billion years ago, explaining evidence for ancient ice-covered lakes.

Partial desiccation of the Mediterranean Sea may have boosted magmatism during the Messinian epoch.

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.

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.

Bursts of methane stored in the Martian subsurface may explain intermittent warm climates on ancient Mars, according to numerical simulations. Sedimentary evidence for palaeolakes requires infrequent, yet sustained, lake-forming climates.

If CO₂ emissions after 2015 do not exceed 200 GtC, climate warming after 2015 will fall below 0.6 °C in 66% of CMIP5 models, according to an analysis based on combining a simple climate–carbon-cycle model with estimated ranges for key climate system properties.

Atmospheric organic compounds are central to key chemical processes that influence air quality. Concurrent measurements of a wide range of these compounds, including previously unmeasured ones, provide closure on OH reactivity.

Microbes on glacial snow and ice reduce albedo and increase melting. Field experiments show that nutrient and meltwater additions increase microbial abundance and that areas of microbe-covered snow generate increased snowmelt.

Productivity in the eastern equatorial Pacific is limited by the availability of iron. Geochemical analyses of a 100,000-year-long sediment core suggest that pulses of dust deposition during Heinrich stadials fuelled primary productivity.

Seismic waves can trigger further fault slip. Analysis of seismic and geodetic data shows that seismic waves from the 2016 Kaikōura, New Zealand earthquake were amplified by subduction zone sediments, triggering slow fault slip up to 600 km away.

Earthquakes can occur at great depths in the Earth, within subducting tectonic plates. Deformation experiments suggest these deep earthquakes can be triggered by localized heating of the slabs under high pressures.

Super-eruptions are fed by large magma reservoirs. Geochemical analyses of volcanic rocks erupted in New Mexico suggest the magma was stored under cool conditions in the crust for 600,000 years, before late-stage heating triggered an eruption.

Unloading of the lithosphere due to reduced sea level in the Mediterranean 6 million years ago may have triggered magmatism around the region, according to numerical models. The eruptions cannot be easily explained by tectonic processes.

A decrease in mafic continental crust coincides with the rise of O₂ in the Earth’s surface environments about 3 billion years ago, according to an analysis of sediment chemistry. Reduced rates of serpentinization of mafic material, which produces chemicals that react with O₂, could explain the link.

Impacts could have driven transient subduction events on the Hadean Earth, according to numerical simulations. The scenario reconciles evidence for tectonic activity with that for an otherwise tectonically stagnant early Earth.