Nature Geoscience. doi:10.1038/ngeo265

Authors: Eric Kirby, Kelin Whipple & Nathan Harkins

The devastating earthquake in the Chinese province of Sichuan struck an area that was not expected to suffer seismic activity of such magnitude. Yet topographic analyses of the region indicate active deformation, suggesting a way of refining maps of earthquake risk elsewhere.

Nature Geoscience. doi:10.1038/ngeo257

Author: Peter J. Webster

Tropical cyclone Nargis wrought havoc in southern Myanmar, with an estimated death toll well above 100,000. Potential future disasters could be alleviated with currently available forecasting skill and effective disaster mitigation plans.

Nature Geoscience. doi:10.1038/ngeo262

Authors: Geert Lenderink & Erik van Meijgaard

Changes in precipitation extremes under greenhouse warming are commonly assumed to be constrained by changes in the amounts of precipitable water in the atmosphere. Global climate models generally predict only marginal changes in relative humidity, implying that the actual amount of atmospheric precipitable water scales with the water vapour content of saturation, which is governed by the Clausius–Clapeyron relation. Indeed, changes in daily precipitation extremes in global climate models seem to be consistent with the 7% increase per degree of warming given by the Clausius–Clapeyron relation, but it is uncertain how general this scaling behaviour is across timescales. Here, we analyse a 99-year record of hourly precipitation observations from De Bilt, the Netherlands, and find that one-hour precipitation extremes increase twice as fast with rising temperatures as expected from the Clausius–Clapeyron relation when daily mean temperatures exceed 12 ∘C. In addition, simulations with a high-resolution regional climate model show that one-hour precipitation extremes increase at a rate close to 14% per degree of warming in large parts of Europe. Our results demonstrate that changes in short-duration precipitation extremes may well exceed expectations from the Clausius–Clapeyron relation. These short-duration extreme events can have significant impacts, such as local flooding, erosion and water damage.

Nature Geoscience. doi:10.1038/ngeo251

Authors: Wolfgang Kiessling, Martin Aberhan & Loïc Villier

Marine calcifying organisms that produce sediments and build reefs generally have skeletons and shells that are composed of either aragonite or calcite. Long-term changes in the estimated Mg/Ca ratios of sea water tend to correspond to changes in the prevailing mineralogy of these creatures. High Mg/Ca ratios are expected to favour the spread of aragonitic organisms, whereas calcitic taxa are thought to benefit from low Mg/Ca ratios. Here we test these patterns throughout the Phanerozoic eon and assess the relative impacts of changing ocean chemistry and mass extinctions on the evolutionary success of calcifying organisms. We find that mass extinctions are more important in regulating long-term patterns of skeletal mineralogy than the Mg/Ca ratios of the global oceans. Furthermore, selective recovery from mass extinctions is usually more important than selective extinction, in driving the Phanerozoic pattern of skeletal mineralogy. But even in the recovery phase there is no clear connection between changes in the dominance of aragonite or calcite and the Mg/Ca ratio of the oceans, thus providing further evidence for the complexity of biotic recoveries.

Nature Geoscience. doi:10.1038/ngeo248

Authors: Simona Bordoni & Tapio Schneider

Monsoons are generally viewed as planetary-scale sea-breeze circulations, caused by contrasts in the thermal properties between oceans and land surfaces that lead to thermal contrasts upon radiative heating. But the radiative heating evolves gradually with the seasons, whereas the onset of monsoon precipitation, and the associated circulation changes such as reversal of surface winds, occur rapidly. Here we use reanalysis data to show that the onset of the Asian monsoon marks a transition between two circulation regimes that are distinct in the degree to which eddy momentum fluxes control the strength of the tropical overturning circulation. Rapid transitions of the circulation between the two regimes can occur as a result of feedbacks between large-scale extratropical eddies and the tropical circulation. Using simulations with an aquaplanet general circulation model, we demonstrate that rapid, eddy-mediated monsoon transitions occur even in the absence of surface inhomogeneities, provided the planet surface has sufficiently low thermal inertia. On the basis of these results, we propose a view of monsoons in which feedbacks between large-scale extratropical eddies and the tropical circulation are essential for the development of monsoons, whereas surface inhomogeneities such as land-sea contrasts are not.

Nature Geoscience. doi:10.1038/ngeo249

Authors: D. Santamaria Tovar, J. Shulmeister & T. R. Davies

The Waiho Loop moraine on South Island, New Zealand, has been interpreted as a consequence of Younger Dryas cooling in New Zealand, and thus as evidence for inter-hemisphere synchroneity of climate change. However, recent work has challenged both the timing of the event and whether strong cooling was necessary to initiate the advance. Here, we characterize the sedimentology of the moraine to assess the possible causes of the advance. Our analysis shows that the composition of the Waiho Loop moraine is different from other moraines in the region, with respect to both the composition and the type of clasts present. We deduce that the moraine represents the end product of a major landslide onto the Franz Josef glacier, which triggered a substantial glacial advance. In combination with the revised age and temperature estimates for this region, our results suggest that there was no significant climatic forcing of this advance, including an alternative precipitation-driven model. Our study shows that glacial moraines are not necessarily climatic in origin, which must be taken into account when evaluating the mass balance responses of glacial systems.

Nature Geoscience. doi:10.1038/ngeo252

Authors: Dries Huygens, Pascal Boeckx, Pamela Templer, Leandro Paulino, Oswald Van Cleemput, Carlos Oyarzún, Christoph Müller & Roberto Godoy

Nature Geoscience. doi:10.1038/ngeo254

Authors: Lenny Winkel, Michael Berg, Manouchehr Amini, Stephan J. Hug & C. Annette Johnson

Nature Geoscience. doi:10.1038/ngeo250

Authors: Gabriel Gutiérrez-Alonso, Javier Fernández-Suárez, Arlo B. Weil, J. Brendan Murphy, R. Damian Nance, Fernando Corfú & Stephen T. Johnston