Evaluating Global Warming Potentials as Historical Temperature Proxies: an application of ACC2 Inverse Calculation

Global Warming Potentials (GWPs) are evaluated as proxies of the historical temperature by applying them to convert historical CH4 and N2O emissions to equivalent CO2 emissions. Our GWP analysis is based on the historical Earth system evolution obtained from the inverse calculation for the Aggregated Carbon Cycle, Atmospheric Cycle, and Climate Model (ACC2). Indices higher than the Kyoto GWPs are required to reproduce the historical temperature. The GWP for N2O, in particular, does not approximate the historical temperature with any time horizon because the GWP definition and calculations assume a background system different from the ACC2 inversion results. In addition, indices have to be progressively updated upon the acquisition of new measurements and/or the change in our understanding on the Earth system processes.global warming potentials

Induced Discounting and Its Implications to Catastrophic Risk Management

The implication of risks for justifying long-term investment remains a controversial issue. For example, how can we justify mitigation efforts for a 200-year flood that may, in fact, occur in one year or in 300 years? Discount rates obtained from capital markets are linked to assets with lifespans of a few decades and, as such, may significantly underestimate the results of long-term mitigations. In this paper, we show that the explicit treatment of extreme catastrophic events and related uncertain time horizons and risks induce dynamically adjusted discount rates, conditional on the degree of social commitment to mitigate risk. In particular, the standard time geometric (exponential) discount factors are induced by an event with time horizons characterized by a "memoryless" geometric (exponential) probability distribution. A set of such events induces declining time inconsistent discount rates that are dominated by least probable extreme events. In general, risk affects discount rates, which alter the optimal mitigation efforts that in turn, change the risk. We show that the induced discount factors can be analyzed by solving stochastic optimization problems. Our simulation results indicate that the misperception of time inconsistency associated with induced discounting may dramatically effect - delay or provoke - the possibility of catastrophic collapse

Unconventional Current Scaling and Edge Effects for Charge Transport through Molecular Clusters

Metal–molecule–metal junctions are the key components of molecular electronics circuits. Gaining a microscopic understanding of their conducting properties is central to advancing the field. In the present contribution, we highlight the fundamental differences between single-molecule and ensemble junctions focusing on the fundamentals of transport through molecular clusters. In this way, we elucidate the collective behavior of parallel molecular wires, bridging the gap between single molecule and large-area monolayer electronics, where even in the latter case transport is usually dominated by finite-size islands. On the basis of first-principles charge-transport simulations, we explain why the scaling of the conductivity of a junction has to be distinctly nonlinear in the number of molecules it contains. Moreover, transport through molecular clusters is found to be highly inhomogeneous with pronounced edge effects determined by molecules in locally different electrostatic environments. These effects are most pronounced for comparably small clusters, but electrostatic considerations show that they prevail also for more extended systems.We thank D. A. Egger, E. Lortscher, and M. Brandbyge for stimulating discussions and G. Nascimbeni for performing additional test calculations. The authors are also grateful for the thoughtful and detailed comments of the referees, which helped us to compile a more insightful manuscript. We are grateful for financial support by the Austrian Science Fund (FWF): P24666-N20, P28631-N36, and P28051-N36. N.P. acknowledges support from the Center for Nanostructured Graphene, sponsored by the Danish National Research Foundation, Project No. DNRF103, from Villum fonden (Grant 00013340), and from the EU H2020 Project No. 676598, ‘‘MaX: Materials at the eXascale’’ Center of Excellence in Supercomputing Applications. ICN2 is funded by the CERCA Programme/Generalitat de Catalunya and is supported by the Severo Ochoa program from the Spanish MINECO (Grant SEV-2013-0295). Electronic structure calculations have been performed using the cluster of the division for high-performance computing at the Graz University of Technology and the Vienna Scientific Cluster. Transport calculations have been performed using the Marenostrum supercomputer of the Barcelona Supercomputing Center (BSC).Peer ReviewedPostprint (published version

International cooperation on Earth observation in the course of GEOSS An evaluation based on game theoretic and economic concepts

Growing environmental concern has fueled the discussion about the establishment of an international institutional arrangement for cooperation on Earth observation. The Global Earth Observation System of Systems (GEOSS) comes as a timely solution, bundling data, technologies and existing observation systems, and providing crucial information about the state of our Earth. However, the implementation of GEOSS faces challenges; some of them are related to the fact that contribution to GEOSS is voluntary. Additionally, benefits of GEOSS are enjoyed by contributors and non-contributors alike, such that GEOSS can be classified as a public good, whose provision is usually corrupted by "freeriding". This paper identifies challenges in managing and implementing GEOSS as a public good. To figure out resolutions and scenarios we examine how these problems are discussed in economic and game theoretical literature. We further examine problems concerning the user integration of GEOSS, and the interaction between Earth observation science and policy

Identifying benefits and challenges arising from the voluntary provision of GEOSS

Even though the efforts to contribute to and sustain the Global Earth Observation System of Systems (GEOSS) are voluntary, the derived benefits will be enjoyed by contributors and non-contributors alike. Thus, GEOSS can be classified as a public good, whose provision is prone to "free- riding". We analyze the benefits of participating in GEO (Group on Earth Observation) and GEOSS as well as the potential problems arising from voluntary contribution to GEOSS. We survey economic and game theoretic literature to see what type of problems, related to the provision of public goods, are described. Secondly, we conduct a survey among individuals involved in various GEOSS tasks, to find out about their perception, benefits and problems regarding GEO and GEOSS. First results show that benefits from participating in GEO include improved networking opportunities and visibility for work. Overall, contribution to GEOSS was perceived as rather low and lacking financial support was regarded as impediment

Uncertainty in soil data can outweigh climate impact signals in crop yield simulations

Global gridded crop models (GGCMs) are increasingly used for agro-environmental assessments and estimates of climate change impacts on food production. Recently, the influence of climate data and weather variability on GGCM outcomes has come under detailed scrutiny, unlike the influence of soil data. Here we compare yield variability caused by the soil type selected for GGCM simulations to weather-induced yield variability. Without fertilizer application, soil-type-related yield variability generally outweighs the simulated inter-annual variability in yield due to weather. Increasing applications of fertilizer and irrigation reduce this variability until it is practically negligible. Importantly, estimated climate change effects on yield can be either negative or positive depending on the chosen soil type. Soils thus have the capacity to either buffer or amplify these impacts. Our findings call for improvements in soil data available for crop modelling and more explicit accounting for soil variability in GGCM simulations

Managing Climate Risk

At the heart of the traditional approach to strategy in the climate change dilemma lies the assumption that the global community, by applying a set of powerful analytical tools, can predict the future of climate change accurately enough to choose a clear strategic direction for it. We claim that this approach might involve underestimating uncertainty in order to lay out a vision of future events sufficiently precise to be captured in a discounted cost flow analysis in integrated assessment models. However, since the future of climate change is truly uncertain, this approach might at best be marginally helpful and at worst downright dangerous: underestimating uncertainty can lead to strategies that do not defend the world against unexpected and sometimes even catastrophic threats. Another danger lies on the other extreme: if the global community can not find a strategy that works under traditional analysis or if uncertainties are too large that clear messages are absent, they may abandon the analytical rigor of their planning process altogether and base their decisions on good instinct and consensus of some future process that is easy to agree upon. In this paper, we try to outline a system to derive strategic decisions under uncertainty for the climate change dilemma. What follows is a framework for determining the level of uncertainty surrounding strategic decisions and for tailoring strategy to that uncertainty. Our core argument is that a robust strategy towards climate change involves the building of a technological portfolio of mitigation and adaptation measures that includes sufficient opposite technological positions to the underlying baseline emission scenarios given the uncertainties of the entire physical and socioeconomic system in place. In the case of mitigation, opposite technological positions with the highest leverage are particular types of sinks. A robust climate risk management portfolio can only work when the opposite technological positions are readily available when needed and therefore have to be prepared in advance. It is precisely the flexibility of these technological options which has to be quantified under the perspective of the uncertain nature of the underlying system and compared to the cost of creating these options, rather than comparing their cost with expected losses in a net present value type analysis. We conclude that climate policy - especially under the consideration of the precautionary principle - would look much different if uncertainties would be taken explicitly into account

Impacts and Uncertainties of +2°C of Climate Change and Soil Degradation on European Crop Calorie Supply

Even if global warming is kept below +2°C, European agriculture will be significantly impacted. Soil degradation may amplify these impacts substantially and thus hamper crop production further. We quantify biophysical consequences and bracket uncertainty of +2°C warming on calories supply from ten major crops and vulnerability to soil degradation in Europe using crop modelling. The Environmental Policy Integrated Climate (EPIC) model together with regional climate projections from the European branch of the Coordinated Regional Downscaling Experiment (EURO-CORDEX) were used for this purpose. A robustly positive calorie yield change was estimated for the EU Member States except for some regions in Southern and South-Eastern Europe. The mean impacts range from +30 Gcal ha–1 in the north, through +25 and +20 Gcal ha–1 in Western and Eastern Europe, respectively, to +10 Gcal ha–1 in the south if soil degradation and heat impacts are not accounted for. Elevated CO2 and increased temperature are the dominant drivers of the simulated yield changes in high-input agricultural systems. The growth stimulus due to elevated CO2 may offset potentially negative yield impacts of temperature increase by +2°C in most of Europe. Soil degradation causes a calorie vulnerability ranging from 0 to 80 Gcal ha–1 due to insufficient compensation for nutrient depletion and this might undermine climate benefits in many regions, if not prevented by adaptation measures, especially in Eastern and North-Eastern Europe. Uncertainties due to future potentials for crop intensification are about two to fifty times higher than climate change impacts

Comparing the quality of crowdsourced data contributed by expert and non-experts

There is currently a lack of in-situ environmental data for the calibration and validation of remotely sensed products and for the development and verification of models. Crowdsourcing is increasingly being seen as one potentially powerful way of increasing the supply of in-situ data but here are a number of concerns over the subsequent use of the data, in particular over data quality. This paper examined crowdsourced data from the Geo-Wiki crowdsourcing tool for land cover validation to determine whether there were significant differences in quality between the answers provided by experts and non-experts in the domain of remote sensing and therefore the extent to which crowdsourced data describing human impact and land cover can be used in further scientific research. The results showed that there was little difference between experts and non-experts in identifying human impact although results varied by land cover while experts were better than non-experts in identifying the land cover type. This suggests the need to create training materials with more examples in those areas where difficulties in identification were encountered, and to offer some method for contributors to reflect on the information they contribute, perhaps by feeding back the evaluations of their contributed data or by making additional training materials available. Accuracies were also found to be higher when the volunteers were more consistent in their responses at a given location and when they indicated higher confidence, which suggests that these additional pieces of information could be used in the development of robust measures of quality in the future