Foraminifera reveal past sea-surface temperatures

Spatial changes in marine plankton (planktonic foraminifera) species assemblages reveal steeper thermal gradients in the North Atlantic during the Last Glacial Maximum than simulated by climate models, according to a macroecological analysis of marine sediment cores. The image shows fossil planktonic foraminifera from the Caribbean Sea. Each shell measures a few hundreds of micrometres and the shape and colour can be used to identify species and reconstruct past biodiversity and biogeographical patterns.

See Jonkers et al.

Reducing air pollution

Air pollution is a problem around the world, including in Africa, a region that has received little international attention. Actions are urgently needed to protect Africa’s air quality. The image shows industrial pollution rising from a factory chimney.

See Pope et al.

Grand Canyon cave illuminates past climate

Early Holocene groundwater recharge rates were higher than modern rates in the Grand Canyon region, likely due to strengthening of the North American monsoon, according to a speleothem record and palaeoclimate modelling. The image shows a calcite stalagmite from a Grand Canyon cave.

See Lachniet et al.

Arctic warmth from blowing snow

Fine sea salt aerosols produced by blowing snow in the Arctic impact cloud properties and warm the surface, according to observations from the MOSAiC expedition. The image shows the polar night during the MOSAiC expedition in December 2019, with extensive blowing snow observed over the central Arctic sea ice surface in the lights of the ice-bound research vessel Polarstern.

See Gong et al.

Long-lived marine plastic

A global, 3D mass budget of marine plastic suggests that larger items contribute more than 95% of buoyant plastics by mass and are longer-lived than previously estimated. The image shows plastic debris on a beach on Mabul Island, Borneo.

See Kaandorp et al.

Methane released from groundwater springs as Arctic glaciers retreat

Groundwater springs formed during the retreat of a melting glacier are likely hotspots of methane emissions in the high Arctic, according to measurements of methane concentrations in springs at central Svalbard. The image shows a cave at Von Postbreen glacier that has been formed by the large volume of glacial meltwater that flows through it during summer. During winter, extensive proglacial icing forms at its mouth and extends across the entire floodplain in front of the glacier, which is visible through the cave opening in the image.

See Kleber et al.

Mantle plume activity forged by ancient ocean chemistry

Correlation between large igneous province activity and the ages of banded iron formations suggests that the latter may have facilitated mantle plume upwelling in the Archean and Proterozoic Earth. The image shows dark bands of iron oxides interlayered with gold bands of quartz and amphibole and red-orange bands of chert containing iron oxide inclusions from a metamorphosed banded iron formation in the Hamersley Basin of Western Australia.

See Keller et al.

Sedimentation from eruption column collapse

Analogue experiments suggest that submarine terraced deposits of caldera-forming explosive eruptions result from periodic collapses of the eruption column. The image shows a plan view of ground-hugging gravity currents spreading from the base of a particle fountain experiment modelling a collapsing eruption column.

See Gilchrist et al.

Lakes fed by hidden glacier melt

According to analysis of satellite observations and bathymetric measurements, the estimated glacier mass loss across the Himalaya over the past 20 years increases by 7% when subaqueous melting from lake-terminating glaciers is accounted for. The image shows a glacial lake below Shishapangma — the 14th-highest mountain in the world — in the Tibet Autonomous Region, China.

See Bolch et al.

Pollution in the night

Measurements show that night-time production of atmospheric nitrate radicals increased in China but decreased in Europe and the USA from 2014 to 2019. This suggests the increasing contribution of night-time atmospheric oxidation in China — and potentially other developing countries — to air pollution. The image shows Beijing at night with bright lights corresponding with sites of active anthropogenic emissions.

See Lu et al.

Dwindling phosphorus in paddy soils

Plant-available phosphorus declines in paddy soils as atmospheric CO2 increases, according to long-term free air carbon dioxide enrichment (FACE) experiments on rice plants in China. The image shows an aerial view of a study site.

See Zhu et al.

Looking up at the Martian sky

Meteorological measurements from NASA’s Perseverance rover on Mars reveal a diversity of processes at work in the atmospheric boundary layer at Jezero Crater over a range of temporal scales. The cover shows SkyCam images of the Martian sky that enable monitoring of suspended dust and clouds, with rover hardware sometimes also visible in the camera frame.

See Rodriguez-Manfredi et al.