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Engelhardt M.,University of Oslo | Schuler T.V.,University of Oslo | Andreassen L.M.,Norwegian Water Resources and Energy Direct.
Hydrology and Earth System Sciences | Year: 2014

Glacierised catchments show a discharge regime that is strongly influenced by snow and glacier meltwaters. In this study, we modelled the mass balance and discharge rates for three highly glacierised catchments (>50% glacier cover) in western Norway over the period 1961-2012. The spatial pattern of the catchments follows a gradient in climate continentality from west to east. The model input were gridded temperature and precipitation values from seNorge (http://senorge.no) which are available at daily resolution. The model accounted for accumulation of snow, transformation of snow to firn and ice, evaporation and melt. Calibration and validation were performed for each catchment based on measurements of seasonal glacier mass balances and daily discharge rates, as additional validation data served daily melt rates from sonic rangers located in the ablation zones of two of the glaciers. The discharge sources snowmelt, glacier melt and rain were analysed with respect to spatial variations and temporal evolution. Model simulations reveal an increase in the relative contribution from glacier melt to total discharge for the three catchments from less than 10% in the early 1990s to 15-30% in the late 2000s. The decline in precipitation by 10-20% in the same period was therefore overcompensated, resulting in an increase in annual discharge by 5-20%. Annual discharge sums and annual glacier melt are most strongly correlated with annual and winter precipitation at the most maritime glacier and, with increased climate continentality, variations in both glacier melt contribution and annual discharge are becoming more strongly correlated with variations in summer temperatures. Therefore, glaciers in more continental climates are especially vulnerable to decrease in both annual and summer discharge with continued rise in summer temperatures and subsequent decrease in glacier extent. This may lead to significant changes to the discharge regime, with increase during spring but decline later in the year, especially for catchments in less maritime climate conditions. © Author(s) 2014.

Elliott J.,University of Chicago | Elliott J.,Argonne National Laboratory | Elliott J.,Columbia University | Deryng D.,University of East Anglia | And 28 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

We compare ensembles of water supply and demand projections from 10 global hydrological models and six global gridded crop models. These are produced as part of the Inter-Sectoral Impacts Model Intercomparison Project, with coordination from the Agricultural Model Intercomparison and Improvement Project, and driven by outputs of general circulation models run under representative concentration pathway 8.5 as part of the Fifth Coupled Model Intercomparison Project. Models project that direct climate impacts to maize, soybean, wheat, and rice involve losses of 400- 1,400 Pcal (8-24% of present-day total) when CO2 fertilization effects are accounted for or 1,400-2,600 Pcal (24-43%) otherwise. Freshwater limitations in some irrigated regions (western United States; China; and West, South, and Central Asia) could necessitate the reversion of 20-60 Mha of cropland from irrigated to rainfed management by end-of-century, and a further loss of 600-2,900 Pcal of food production. In other regions (northern/eastern United States, parts of South America, much of Europe, and South East Asia) surplus water supply could in principle support a net increase in irrigation, although substantial investments in irrigation infrastructure would be required.

Pfaffhuber A.A.,Norwegian Geotechnical Institute | Bastani M.,Uppsala University | Cornee S.,ETH Zurich | Romoen M.,NGl | And 5 more authors.
Near Surface 2010 - 16th European Meeting of Environmental and Engineering Geophysics | Year: 2010

Quick clay is highly sensitive, marine clay with an unstable mineral structure due to post glacial heaving and consequent leaching of saline pore fluids by surface- and groundwater. Extended quick clay layers pose a serious geo-hazard in Scandinavia and North America and need to be delineated in detail. Geophysical methods, especially resistivity methods, have been tested for small scale quick clay mapping at a research site close to Oslo, Norway. By scrutinizing results from Electric Resistivity Tomography ERT and Controlled Source Radiomagnetotellurics (CSRMT) and integrating them to geotechnical borehole data with the help of a resistivity logging tool (RCPT) we confirm the value of this integrated study for quick clay hazard zonation. ERT is an ideal tool to interpolate limited borehole results and thus to provide a more cost efficient and detailed result than with boreholes alone. Our resistivity data from ERT, RCPT and lab measurements are consistent and appear isotropic.

Solberg R.,Norwegian Computing Center | Killie M.A.,Norwegian Meteorological Institute | Andreassen L.M.,Norwegian Water Resources and Energy Direct. | Konig M.,Norwegian Polar Institute
IOP Conference Series: Earth and Environmental Science | Year: 2014

The CryoClim project has developed a new operational and permanent service for long-term systematic climate monitoring of the cryosphere. The product production and the product repositories are hosted by mandated organisations, and the service is delivered through a state-of-the-art web service and web portal. The service provides sea ice and snow products of global coverage and glacier products covering Norway (mainland and Svalbard). The sea ice sub-service is based on data from passive microwave radiometers (SMMR and SSM/I). The same period is covered by snow cover extent products based on passive microwave radiometers (SMMR and SSM/I) and optical (AVHRR from 1982). Glacier maps, including glacier area outline and glacier lakes have been generated from Landsat TM, ETM+ and historic topographic maps for all glaciers in mainland Norway starting the time series from 1952. For Svalbard, glacier products are based on optical data (SPOT and MODIS) for glacier area outline and glacier snow line, and SAR data (ERS-1, ERS-2, Envisat ASAR and Radarsat) for glacier surface type. The period covered with satellite data starts in the early 1990s. The glacier area outline time series has in Svalbard also been extended with map data and aerial images from earlier days.

Schewe J.,Potsdam Institute for Climate Impact Research | Heinke J.,Potsdam Institute for Climate Impact Research | Heinke J.,Kenya International Livestock Research Institute | Gerten D.,Potsdam Institute for Climate Impact Research | And 24 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Water scarcity severely impairs food security and economic prosperity in many countries today. Expected future population changes will, in many countries as well as globally, increase the pressure on available water resources. On the supply side, renewable water resources will be affected by projected changes in precipitation patterns, temperature, and other climate variables. Here we use a large ensemble of global hydrological models (GHMs) forced by five global climate models and the latest greenhouse-gas concentration scenarios (Representative Concentration Pathways) to synthesize the current knowledge about climate change impacts on water resources. We show that climate change is likely to exacerbate regional and global water scarcity considerably. In particular, the ensemble average projects that a global warming of 2 °C above present (approximately 2.7 °C above preindustrial) will confront an additional approximate 15%of the global population with a severe decrease in water resources and will increase the number of people living under absolute water scarcity (<500m3 per capita per year) by another 40% (according to some models, more than 100%) compared with the effect of population growth alone. For some indicators of moderate impacts, the steepest increase is seen between the present day and 2 °C, whereas indicators of very severe impacts increase unabated beyond 2 °C. At the same time, the study highlights large uncertainties associated with these estimates, with both global climate models and GHMs contributing to the spread. GHM uncertainty is particularly dominant in many regions affected by declining water resources, suggesting a high potential for improved water resource projections through hydrological model development.

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