ALBERT

Beschreibung: Nature Geoscience 7, 860 (2014). doi:10.1038/ngeo2301 Author: Jay J. Ague Aqueous subduction-zone fluids contain CO2 and methane. New calculations indicate that these fluids also host a wide array of organic carbon species, in concentrations sufficient to influence the deep carbon cycle.

Beschreibung: Nature Geoscience 7, 925 (2014). doi:10.1038/ngeo2278 Authors: Devin McPhillips, Paul R. Bierman & Dylan H. Rood

Beschreibung: Nature Geoscience 7, 920 (2014). doi:10.1038/ngeo2284 Authors: Peter B. Reich, Sarah E. Hobbie & Tali D. Lee

Beschreibung: Nature Geoscience 7, 931 (2014). doi:10.1038/ngeo2296 Author: Colin Goldblatt, Tyler D. Robinson, Kevin J. Zahnle & David Crisp

Beschreibung: Nature Geoscience 7, 321 (2014). doi:10.1038/ngeo2163 Climate change could compromise food security over the coming century. Scientists working towards mitigation and adaptation have to win over those who work on the land.

Beschreibung: Nature Geoscience 7, 324 (2014). doi:10.1038/ngeo2153 Authors: Paolo D'Odorico & Maria Cristina Rulli Large tracts of agricultural land are being bought up by external investors. Turning the land into a commodity can have detrimental effects, for generations to come, on the local communities that sell or lease the land.

Beschreibung: Nature Geoscience 7, 328 (2014). doi:10.1038/ngeo2158 Author: Tamara Goldin

Beschreibung: Nature Geoscience 7, 329 (2014). doi:10.1038/ngeo2145 Author: Sanjoy M. Som A dense early atmosphere has been invoked to explain the strong greenhouse effect inferred for early Mars. Yet an analysis of the smallest impact craters suggests that the atmospheric pressure on Mars 3.6 billion years ago was surprisingly low.

Beschreibung: Nature Geoscience 7, 335 (2014). doi:10.1038/ngeo2137 Authors: Edwin S. Kite, Jean-Pierre Williams, Antoine Lucas & Oded Aharonson The decay of the martian atmosphere—which is dominated by carbon dioxide—is a component of the long-term environmental change on Mars from a climate that once allowed rivers to flow to the cold and dry conditions of today. The minimum size of craters serves as a proxy for palaeopressure of planetary atmospheres, because thinner atmospheres permit smaller objects to reach the surface at high velocities and form craters. The Aeolis Dorsa region near Gale crater on Mars contains a high density of preserved ancient craters interbedded with river deposits and thus can provide constraints on atmospheric density at the time of fluvial activity. Here we use high-resolution images and digital terrain models from the Mars Reconnaissance Orbiter to identify ancient craters in deposits in Aeolis Dorsa that date to about 3.6 Gyr ago and compare their size distribution with models of atmospheric filtering of impactors. We obtain an upper limit of 0.9 ± 0.1 bar for the martian atmospheric palaeopressure, rising to 1.9 ± 0.2 bar if rimmed circular mesas—interpreted to be erosionally-resistant fills or floors of impact craters—are excluded. We assume target properties appropriate for desert alluvium: if sediment had rock-mass strength similar to bedrock at the time of impact, the paleopressure upper limit increases by a factor of up to two. If Mars did not have a stable multibar atmosphere at the time that the rivers were flowing—as suggested by our results—then a warm and wet CO2/H2O greenhouse is ruled out, and long-term average temperatures were most likely below freezing.

Beschreibung: Nature Geoscience 7, 376 (2014). doi:10.1038/ngeo2119 Authors: Gregor Knorr & Gerrit Lohmann