Articles in 2016

Large earthquakes cause other quakes near and far. Analyses of quakes in Pakistan and Chile suggest that such triggering can occur almost instantaneously, making triggered events hard to detect, and potentially enhancing the associated hazards.

Societal upheaval occurred across Eurasia in the sixth and seventh centuries. Tree-ring reconstructions suggest a period of pronounced cooling during this time associated with several volcanic eruptions.

The amount of carbon dioxide in the atmosphere declined as the Earth entered the last glacial period. Estimates of deep carbonate ion concentrations suggest that a substantial amount of carbon was sequestered in the deep Atlantic Ocean.

Assessments of earthquake risk often assume rupture of a single fault. Analysis of a 1997 Pakistan earthquake reveals that not one but two separate ruptures caused the shaking, implying that cascading events should be factored into forecasts.

Drought management is inefficient because feedbacks between drought and people are not fully understood. In this human-influenced era, we need to rethink the concept of drought to include the human role in mitigating and enhancing drought.

Groundwater flow meddles with hydrological, environmental and geological processes. As water scarcity issues mount for people living above ground, the vast stores of freshwater in the subsurface require research attention.

Economic-grade deposits of copper are hard to find. The aluminium content of magmatic rocks at the surface may provide an indicator of ore deposits buried deep below.

Very small ponds have been omitted from greenhouse gas budgets. Estimates of CO₂ and CH₄ emissions from 427 lakes and ponds show that very small ponds account for 15% of CO₂ and 40% of diffusive CH₄ emissions, but 8.6% of lake and pond area.

Different ocean basins warm at different rates in response to climate change. A coupled carbon–climate model reveals that high carbon emission rates will lead to greater sea-level rise in the Atlantic than the Pacific on centennial timescales.

Porphyry ore deposits are increasingly hard to discover. Geochemical analysis of minerals formed in porphyry systems worldwide shows that the most fertile deposits are associated with excess Al and water-rich magma injections.

Magma reservoirs typically accumulate over hundreds to thousands of years. Yet, geochemical analyses of volcanic rocks from Campi Flegrei suggest activity there was triggered by injections of volatile-rich magma only days before the eruption.

Natural seafloor hydrocarbon seeps are responsible for roughly half of the oil released into the ocean. As these oils and gases rise to the surface, they transport nutrients upwards, benefiting phytoplankton in the upper sunlit layer.

Humanity's nitrogen pollution footprint has increased by a factor of six since the 1930s. A global analysis reveals that a quarter of this nitrogen pollution is associated with the production of internationally traded products.

Variability in solar UV radiation is uncertain, but it affects Earth’s climate. Simulations of the ozone response to various data sets of spectral solar irradiance show that high-amplitude solar variability is inconsistent with ozone observations.

Groundwater flow redistributes heat in the Earth’s crust. Numerical simulations of groundwater flow show net cooling of groundwater basins, as well as cooling of the underlying lithosphere in areas where groundwater flows over large distances.

Natural hydrocarbon seeps account for up to 47% of the oil released into the oceans. In situ and remote measurements of chlorophyll concentrations suggest that natural hydrocarbons enhance productivity in surface waters in the Gulf of Mexico.

Anthropogenic emissions of reactive nitrogen have had severe environmental impacts. An analysis of reactive nitrogen emissions from the production, consumption and transport of commodities attributes roughly a quarter to international trade.