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Université de Fribourg

Assessing coral reef health in the North Ari Atoll (Maldives) using the FoRAM Index

Pisapia, C. ; Kateb, Akram El ; Hallock, P. ; Spezzaferri, Silvia

In: Marine Micropaleontology, 2017, vol. 133, no. Supplement C, p. 50–57

Tropical marine ecosystems are richly diverse, but are experiencing growing pressure from coastal development and tourism. Assessing the status of coral reef communities along gradients of human pressure is necessary to predict recovery capacity of reefs exposed to acute events such as mass bleaching or storm destruction. Islands in the central Maldives Archipelago, which experience three...

Université de Fribourg

A tipping point in refreezing accelerates mass loss of Greenland’s glaciers and ice caps

Noël, B. ; Berg, W. J van de ; Lhermitte, S. ; Wouters, B. ; Machguth, Horst ; Howat, I. ; Citterio, M. ; Moholdt, G. ; Lenaerts, J. T. M. ; Broeke, M. R. van den

In: Nature Communications, 2017, vol. 8, p. 14730

Melting of the Greenland ice sheet (GrIS) and its peripheral glaciers and ice caps (GICs) contributes about 43% to contemporary sea level rise. While patterns of GrIS mass loss are well studied, the spatial and temporal evolution of GICs mass loss and the acting processes have remained unclear. Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote...

Université de Fribourg

Estimation of snowfall limit for the Kashmir Valley, Indian Himalayas, with TRMM PR Bright Band information

Schauwecker, S. ; Rohrer, M. ; Schwarb, M. ; Huggel,, C. ; Dimri, A.P. ; Salzmann, Nadine

In: Meteorologische Zeitschrift, 2016, p. 501–509

Knowing the height of the snowfall limit during precipitation events is crucial for better understanding a number of hydro-climatic processes, for instance glacier-climate interactions or runoff from high mountain catchments. However, knowledge on heights of the phase change during precipitation events is limited by the small number of meteorological measurements available at high altitudes,...

Université de Fribourg

The abandoned ice sheet base at Camp Century, Greenland, in a warming climate

Colgan, William ; Machguth, Horst ; MacFerrin, Mike ; Colgan, Jeff D. ; As, Dirk van ; MacGregor, Joseph A.

In: Geophysical Research Letters, 2016, vol. 43, no. 15, p. 8091–8096

In 1959 the U.S. Army Corps of Engineers built Camp Century beneath the surface of the northwestern Greenland Ice Sheet. There they studied the feasibility of deploying ballistic missiles within the ice sheet. The base and its wastes were abandoned with minimal decommissioning in 1967, under the assumption they would be preserved for eternity by perpetually accumulating snowfall. Here we show...

Université de Fribourg

Robust climate scenarios for sites with sparse observations: a two-step bias correction approach

Rajczak, Jan ; Kotlarski, Sven ; Salzmann, Nadine ; Schär, Christoph

In: International Journal of Climatology, 2016, vol. 36, no. 3, p. 1226–1243

Observed and projected climatic changes demand for robust assessments of climate impacts on various environmental and anthropogenic systems. Empirical-statistical downscaling (ESD) methods coupled to output from climate model projections are promising tools to assess impacts at regional to local scale. ESD methods correct for common model deficiencies in accuracy (e.g. model biases) and scale...

Université de Fribourg

Climate trends and glacier retreat in the Cordillera Blanca, Peru, revisited

Schauwecker, S. ; Rohrer, M. ; Acuña, D. ; Cochachin, A. ; Dávila, L. ; Frey, H. ; Giráldez, C. ; Gómez, J. ; Huggel, C. ; Jacques-Coper, M. ; Loarte, E. ; Salzmann, Nadine ; Vuille, M.

In: Global and Planetary Change, 2014, vol. 119, p. 85–97

The total glacial area of the Cordillera Blanca, Peru, has shrunk by more than 30% in the period of 1930 to the present with a marked glacier retreat also in the recent decades. The aim of this paper is to assess local air temperature and precipitation changes in the Cordillera Blanca and to discuss how these variables could have affected the observed glacier retreat between the 1980s and...

Université de Fribourg

Li/Mg systematics in scleractinian corals: Calibration of the thermometer

Montagna, Paolo ; McCulloch, Malcolm ; Douville, Eric ; Correa, Matthias López ; Trotter, Julie ; Rodolfo-Metalpa, Riccardo ; Dissard, Delphine ; Ferrier-Pagès, Christine ; Frank, Norbert ; Freiwald, André ; Goldstein, Steve ; Mazzoli, Claudio ; Reynaud, Stephanie ; Rüggeberg, Andres ; Russo, Simone ; Taviani, Marco

In: Geochimica et Cosmochimica Acta, 2014, vol. 132, p. 288–310

We show that the Li/Mg systematics of a large suite of aragonitic coral skeletons, representing a wide range of species inhabiting disparate environments, provides a robust proxy for ambient seawater temperature. The corals encompass both zooxanthellate and azooxanthellate species (Acropora sp., Porites sp., Cladocora caespitosa, Lophelia pertusa, Madrepora...

Université de Fribourg

Simulating high-latitude permafrost regions by the JSBACH terrestrial ecosystem model

Ekici, A. ; Beer, C. ; Hagemann, S. ; Boike, J. ; Langer, M. ; Hauck, Christian

In: Geoscientific Model Development, 2014, vol. 7, no. 2, p. 631–647

The current version of JSBACH incorporates phenomena specific to high latitudes: freeze/thaw processes, coupling thermal and hydrological processes in a layered soil scheme, defining a multilayer snow representation and an insulating moss cover. Evaluations using comprehensive Arctic data sets show comparable results at the site, basin, continental and circumarctic scales. Such comparisons...

Université de Neuchâtel

Observed climate variability and change in Urmia Lake Basin, Iran

Delju, A. H. ; Ceylan, A. ; Piguet, Etienne ; Rebetez, M.

In: Theoretical and Applied Climatology, 2013, vol. 111, no. 1-2, p. 285-296

This paper analyzes climate variability and change in the Urmia Lake Basin, northwest of Iran. Annual average of the following data time series has been analyzed by statistical methods: dry bulb temperature, maximum and minimum temperature, precipitation, and number of rainy and snowy days. We have also used mean monthly temperature and precipitation data for analysis of drought spells for the...

Université de Fribourg

Modeled sensitivity of two alpine permafrost sites to RCM-based climate scenarios

Scherler, Martin ; Hauck, Christian ; Hoelzle, Martin ; Salzmann, Nadine

In: Journal of Geophysical Research: Earth Surface, 2013, vol. 18, no. 2, p. 780–794

Climate change as projected by contemporary general circulation models (GCMs) and regional climate models (RCMs) will have a great impact on high latitude and high mountain permafrost. A process-based one-dimensional permafrost model is used to evaluate the sensitivity of two characteristic alpine permafrost sites to changes in climate for a 110 year time period starting 1991 and ending 2100...