Earth

This article shows that mantle plumes -- hot, upwelling portions of the Earth's mantle -- create large quantities of gold-rich crust when they are melted. These gold-rich rocks contain up to 13 times the amount of gold in normal crust.

This means that crust created from mantle plumes represent a rich source of gold and other metals which could be incorporated into mineral deposits. As such, mineral deposits created by sourcing metals from such rocks may be larger or occur more frequently than deposits formed from normal crust.

The El Niño-Southern Oscillation (ENSO) drives many of the catastrophic climate events that occur from one year to the next: floods, droughts, wildfires, and hurricanes.

However, climate scientists do not yet know how ENSO will respond to climate change. A new multi-century reconstruction of ENSO variability, based on fossil corals from Papua New Guinea, reveals a century-long decline in the number of El Niño events starting in the mid-1500s.

Over the last few decades, melting of West Antarctic glaciers has contributed significantly to global sea-level rise. Since 1992, two major outlet glaciers have experienced up to 25 km of landward retreat of their "grounding line," the position at which the glacier margin starts to float.

Understanding how global temperature changes with increasing atmospheric greenhouse gas concentrations, or climate sensitivity, is of central importance to climate change research.

Climate models provide sensitivity estimates that may not fully incorporate slow, long-term feedbacks such as those involving ice sheets and vegetation. Geological studies, on the other hand, can provide estimates that integrate long- and short-term climate feedbacks to radiative forcing.

Plumes of hot, buoyant material are thought to rise from the deepest mantle, near the core-mantle boundary.

In the shallow mantle, the plumes partially melt, and the melt is erupted at the surface at hotspot volcanoes. Several hotspot volcanoes, including those in Hawaii, Samoa, and the Marquesas, exhibit two parallel volcanic lineaments that are geochemically distinct. This geochemical separation is thought to result from the plumes being sourced from the northern side of a large, enriched geochemical and seismological anomaly in the deepest mantle.

This study by Jose Luis Antinao and Eric McDonald assesses the hypothesis that a climatically induced decrease in vegetation density on arid region hillslopes is a major factor behind erosion, sediment transport, and aggradation (sedimentation) downstream.

This linkage is often used to explain sedimentation in alluvial fans during the Late Pleistocene Holocene period (8 to 14-thousand years ago) in the U.S. Southwest deserts. Antinao and McDonald compiled paleo-botanical and alluvial fan sedimentation histories during this period in the Mojave and northern Sonoran deserts.

Charles Ferguson and colleagues describe the discovery of a volcano in the Mojave Desert of the southwestern United States that has implications for understanding the mechanism for super-eruptions, a class of volcanic eruption that taps very large (greater than 100 cubic kilometers) amounts of magma in a very short period of time (hours to days).

Marine zoning in the Pacific Ocean, in combination with other measures, could significantly improve numbers of heavily overfished bigeye tuna and improve local economies, a fish modelling study has found.

Experts are urging policy makers to preserve mangroves and their essential services to nature and humanity alike, saying their replacement with shrimp farms and other forms of development is a bad economic tradeoff both short and long-term.

CORVALLIS, Ore. – Eight researchers in a new report have suggested that climate change is causing additional stress to many western rangelands, and as a result land managers should consider a significant reduction, or in some places elimination of livestock and other large animals from public lands.

Global climate models abound. What is harder to pin down, however, is how a warmer global temperature might affect any specific region on Earth.

Dr. Marco Tedesco, associate professor of earth and atmospheric sciences at The City College of New York, and a colleague have made the global local. Using a regional climate model and the output of three global climate models, they predict how different greenhouse gas scenarios would change the face of Greenland over the next century and how this would impact sea level rise.

WASHINGTON — November 13, 2012 — Scientists from the American Meteorological Society (AMS) and University of California, Berkeley have demonstrated that plants and soils could release large amounts of carbon dioxide as global climate warms. This finding contrasts with the expectation that plants and soils will absorb carbon dioxide and is important because that additional carbon release from land surface could be a potent positive feedback that exacerbates climate warming.

Optical Boomerangs

P. Aleahmad et al.

Physical Review Letters (forthcoming)

P. Zheng et al.Physical Review Letters, 109, 193901 (2012)

Bending light around corners is usually done with mirrors, but now scientists have realized self-bending light beams that propagate along curved paths.

Analysis of 90 years of observational data has revealed that summer climates in regions across the globe are changing -- mostly, but not always, warming --according to a new study led by a scientist from the Cooperative Institute for Research in Environmental Sciences headquartered at the University of Colorado Boulder.

"It is the first time that we show on a local scale that there are significant changes in summer temperatures," said lead author CIRES scientist Irina Mahlstein. "This result shows us that we are experiencing a new summer climate regime in some regions."