Outreach

Under the ice of Antarctica lie the roots of Himalayan-style mountains, according to two geologists tied to the Australian National University (ANU), who reached that conclusion from 1,712 zircon crystals that glaciers had carried off the continent and dumped on the surrounding seafloor.

A stretch of sediment beneath the North Atlantic preserves a magnetic reversal that took about 70,000 years to finish. Rather than switching cleanly, Earth's field wandered through repeated disturbances before settling into its opposite polarity. The geological analysis, published in Communications Earth & Environment, examined two reversals roughly 40 million years ago. Yuhji Yamamoto of Japan's Kochi University led the work with colleagues in France, Japan and the University of Utah.

The opening and closing of gateways that connect major ocean basins can profoundly change the intensity and physical characteristics of major ocean currents. One such gateway is currently present at the southern tip of Africa1. Here, the Agulhas Current brings warm, salty water poleward in the southwest Indian Ocean, most of which loops back and returns to the same ocean basin. A portion of the flow, however, breaks off in eddies that travel across the South Atlantic and can become incorporated in equatorward flowing currents off the coast of Brazil.

Iron is an essential micronutrient for life, enabling processes such as respiration, photosynthesis, and DNA synthesis. Its availability is often a limiting resource in today’s oceans, which means that increasing its flux into the oceans could raise the amount of carbon fixed by phytoplankton, with consequences for global climate. Iron reaches the oceans and terrestrial ecosystems through rivers, glacial melt, hydrothermal activity, and, above all, wind.

The African savanna is one of the most recognizable landscapes on the planet: open grass, a few flat-topped trees, herds of wild animals moving through it. The date usually attached to its start is around 10 million years ago, when grasses running on a drought-hardy kind of photosynthesis spread through the tropics. But the ground was already open long before those grasses arrived.

Over the past 230,000 years, the growth and retreat of the Icelandic ice sheet have led to major changes in the seawater chemistry of the North Atlantic, caused by the interaction between volcanism and ice in Iceland. Scientists at the Institute of Environmental Physics at Heidelberg University have demonstrated this using sediment cores from the northeastern Atlantic – the Rockall Plateau.