Inferring global wind energetics from a simple Earth system model based on the principle of maximum entropy production
Summary: This paper proposes a method to infer global wind energetics of the atmosphere. It uses the energy fluxes obtained with a climate box-model previously proposed by Herbert et al., based on the maximization of entropy production (MEP) principle, to compute annual mean winds. Specific details of the circulation are not recovered, as the atmosphere is represented with only one layer, but global figures are well captured.
Climate and carbon cycle dynamics in a CESM simulation from 850–2100 CE
Summary: We present the first last millennium simulation with the Community Earth System Model (CESM) including an interactive carbon cycle in both ocean and land component. Volcanic eruptions emerge as strongest forcing factor for the preindustrial climate and carbon cycle. We estimate the climate-carbon cycle feedback in CESM to be at the lower bounds of empirical estimates (1.3 ppm/°C). The time of emergence for interannual global land and ocean carbon uptake rates are 1947 and 1877, respectively.
F. Lehner, F. Joos, C. C. Raible, J. Mignot, A. Born, K. M. Keller, and T. F. Stocker Earth Syst. Dynam. Discuss., 6, 351-406, doi:10.5194/esdd-6-351-2015, 2015 AbstractDiscussion Paper (PDF, 5001 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for ESD
26 Feb 2015
Ice-supersaturation and the potential for contrail formation in a changing climate
Summary: Aviation can impact on climate via contrails, which are often clearly visible in the sky. Contrail formation requires particular cold/moist atmospheric conditions at cruise altitudes. Climate change is expected to change these conditions. Using simulations from several climate models we conclude that by the end of the century the probability of contrail formation could decrease in the tropics by 9% and increase in polar regions by 5%. There is no consenus on the likely change in mid-latitudes.
Appraising the capability of a land biosphere model as a tool in modelling land surface interactions: results from its validation at selected European ecosystems
Summary: This study evaluated the ability of the SimSphere SVAT model in estimating key parameters characterising land surface interactions. Results confirmed the correspondence of the model structure to real conditions for which it had been parameterised, evidencing its ability to reproduce outputs akin to the in situ data. To our knowledge this is the first comprehensive validation of the model. Findings are very important since use of the model is growing globally as educational and research tool.
M. R. North, G. P. Petropoulos, G. Ireland, and J. P. McCalmont Earth Syst. Dynam. Discuss., 6, 217-265, doi:10.5194/esdd-6-217-2015, 2015 AbstractDiscussion Paper (PDF, 8692 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for ESD
09 Feb 2015
Inter-annual and seasonal trends of vegetation condition in the Upper Blue Nile (Abbay) basin: dual scale time series analysis
Summary: This study concludes that integrated analysis of course and fine scale, inter-annual & intra-annual trends enables a more robust identification of changes in vegetation condition. Seasonal trend analysis was found to be very useful in identifying changes in vegetation condition that could be masked if only inter-annual vegetation trend analysis was performed. The finer scale intra-annual trend analysis revealed trends that were more linked to human activities.
Resource acquisition, distribution and end-use efficiencies and the growth of industrial society
Summary: This paper uses observations of global and national energy use to attempt to show that the growth in energy use over the last 160 years can be related to the distribution constraints imposed by the networks that link environmentally-derived resources to points of end use. Having accounted for the distribution efficiency of this global-scale network, we speculate that the observed long-run return rate on energy of ~2.4 %/yr requires regulated deployment of acquisition and end use efficiencies.
Future hydrological extremes: the uncertainty from multiple global climate and global hydrological models
Summary: We assessed future changes in high and low flows globally using runoff projections from Global Hydrological (GHM) driven by Global Climate (GCM) Models under the RCP8.5 scenario. Further, we quantified the relative size of uncertainty from GHMs and from GCMs using ANOVA. We show that GCMs are the major contributors to uncertainty overall, but that GHMs increase their contribution for low flows and can equal or outweigh GCMs uncertainty in snow dominated areas for both high and low flows.
Optimizing cropland cover for stable food production in Sub-Saharan Africa using simulated yield and Modern Portfolio Theory
Summary: Food security is defined as stable access to food of good nutritional quality. In regions where food security is highly dependent on local production it is thus of importance to produce not only enough calories but also to minimize variation in yield. This trade-off is investigated here using simulated crop yield and by selecting relative distributions of crops. The results show a large potential to either increase food production or to decrease its variance by applying optimized crop selection.
Policy support, economic incentives and the adoption of irrigation technology in China
Summary: The econometric analyses results revealed that policy supports via subsidies and extension services have played an important role inpromoting the adoption of irrigation technology. Strikingly, the present irrigation pricing policy has played significant but contradictory roles in promoting the adoption of different types of irrigation technology. Irrigation pricing showed a positive impact on household-based irrigation technology, and a negative impact on community-based irrigation technology.