Volume 9 Issue 12, December 2016

The Intergovernmental Panel on Climate Change is preparing a report on keeping global warming below 1.5 °C. How the panel chooses to deal with the option of solar geoengineering will test the integrity of scientific climate policy advice.

The latitude of the tropical rainbelt is constrained by the energy balance between hemispheres. An expansion of this theory that includes longitudinal variations of atmospheric heating can predict regional changes in tropical precipitation.

Mantle enrichment processes were thought to be limited to parts of oceanic plates influenced by plumes and to continental interiors. Analyses of mantle fragments of the Pacific Plate suggest that such enrichment processes may operate everywhere.

Large quantities of organic carbon are stored in the ocean, but its biogeochemical behaviour is elusive. Size–age–composition relations now quantify the production of tiny organic molecules as a major pathway for carbon sequestration.

The slow instrumental-record warming is consistent with lower-end climate sensitivity. Simulations and observations now show that changing sea surface temperature patterns could have affected cloudiness and thereby dampened the warming.

Tectonic plate interiors are often regarded as relatively inactive. Yet, reconstructions of marine terrace uplift in Angola suggest that underlying mantle flow can rapidly warp Earth's surface far from obviously active plate boundaries.

Cloud feedbacks strongly influence the magnitude of global warming. Climate model simulations show that these feedbacks vary strongly as the spatial patterns of sea surface temperatures change over time.

Ozone is an air pollutant and a greenhouse gas. Simulations with a global chemistry transport model reveal that the spatial distribution of ozone precursor emissions dominates the global ozone burden, and that emissions in the tropics matter most.

Cement production is a source of CO₂. Analysis of carbonation, a process that sequesters CO₂ during the lifetime of cement, suggests that between 1930 and 2013, it has offset 43% of CO₂ emissions from cement production globally.

A lot of methane is emitted from oxygenated seawater, where its production should be inhibited. Seawater incubations and organic matter characterizations reveal that bacteria aerobically produce methane from phosphonates in organic matter.

Organic matter represents a large pool of carbon in the ocean. Radiocarbon and chemical analyses suggest that larger particles are preferentially remineralized in the Pacific Ocean, with smaller particles and molecules persisting longer.

Shifts in the latitude of the tropical rainfall band are constrained by meridional energy fluxes. Calculations show that combining zonal and meridional energy fluxes can explain past regional rainfall variations like the African Humid Period.

Oceanic lithosphere is recycled into the mantle at subduction zones. Analysis of fragments of lower oceanic lithosphere brought to the surface by petit-spot volcanoes suggests this lithosphere may be enriched by melts prior to subduction.

The origin of carbon-rich magmas is unclear. Boron isotopic analysis of carbonatite magmas that formed over the past 2.6 billion years reveals a link to carbon recycled during tectonic plate subduction.

Mantle flow can warp Earth’s surface. Reconstructions of surface deformation in Angola over the past 45,000 years reveal rapid uplift of about 2 mm per year, implying that mantle-induced uplift may occur in quick pulses.