Enhanced Transmission and Reflection of Femtosecond Pulses by a Single Slit

We show that a physical mechanism responsible for the enhanced transmission and reflection of femtosecond pulses by a single subwavelength nanoslit in a thick metallic film is the Fabry-Perot-like resonant excitation of stationary, quasistationary and nonstationary waves inside the slit, which leads to the field enhancement inside and around the slit. The mechanism is universal for any pulse-scatter system, which supports the stationary resonances. We point out that there is a pulse duration limit below which the slit does not support the intraslit resonance.Comment: 4 pages, 3 figure

The impact of air pollutant and methane emission controls on tropospheric ozone and radiative forcing: CTM calculations for the period 1990-2030

To explore the relationship between tropospheric ozone and radiative forcing with changing emissions, we compiled two sets of global scenarios for the emissions of the ozone precursors methane (CH₄), carbon monoxide (CO), non-methane volatile organic compounds (NMVOC) and nitrogen oxides (NO_x) up to the year 2030 and implemented them in two global Chemistry Transport Models. The 'Current Legislation' (CLE) scenario reflects the current perspectives of individual countries on future economic development and takes the anticipated effects of presently decided emission control legislation in the individual countries into account. In addition, we developed a 'Maximum technically Feasible Reduction' (MFR) scenario that outlines the scope for emission reductions offered by full implementation of the presently available emission control technologies, while maintaining the projected levels of anthropogenic activities. Whereas the resulting projections of methane emissions lie within the range suggested by other greenhouse gas projections, the recent pollution control legislation of many Asian countries, requiring introduction of catalytic converters for vehicles, leads to significantly lower growth in emissions of the air pollutants NO_x, NMVOC and CO than was suggested by the widely used and more pessimistic IPCC (Intergovernmental Panel on Climate Change) SRES (Special Report on Emission Scenarios) scenarios (Nakicenovic et al., 2000), which made Business-as-Usual assumptions regarding emission control technology. With the TM3 and STOCHEM models we performed several long-term integrations (1990-2030) to assess global, hemispheric and regional changes in CH₄, CO, hydroxyl radicals, ozone and the radiative climate forcings resulting from these two emission scenarios. Both models reproduce broadly the observed trends in CO, and CH₄ concentrations from 1990 to 2002. <P style='line-height: 20px;'> For the 'current legislation' case, both models indicate an increase of the annual average ozone levels in the Northern Hemisphere by 5ppbv, and up to 15ppbv over the Indian sub-continent, comparing the 2020s (2020-2030) with the 1990s (1990-2000). The corresponding higher ozone and methane burdens in the atmosphere increase radiative forcing by approximately 0.2 Wm^-2. Full application of today's emissions control technologies, however, would bring down ozone below the levels experienced in the 1990s and would reduce the radiative forcing of ozone and methane to approximately -0.1 Wm^-2. This can be compared to the 0.14-0.47 Wm^-2 increase of methane and ozone radiative forcings associated with the SRES scenarios. While methane reductions lead to lower ozone burdens and to less radiative forcing, further reductions of the air pollutants NO_x and NMVOC result in lower ozone, but at the same time increase the lifetime of methane. Control of methane emissions appears an efficient option to reduce tropospheric ozone as well as radiative forcing

New Climate Economics: Methodological Choices and Recommendations

Projections of future impacts, benefits and costs of climate mitigation and adaptation policies are based on both detailed empirical research, and modelling choices and assumptions that frame the analysis. For instance, assumptions about the expected growth of population and incomes drive the projections of greenhouse gas emissions. Assumptions about the pace and nature of innovation, the economy-environment-society interactions and the relative value of future versus current resources affect the estimates of the long-run benefits or costs of climate policies. Assumptions about future population health in the business-as-usual scenario affect the estimates of the health benefits or harms of climate change mitigation and adaptation policies. Further, estimates and assumptions regarding climate variability affect the benefits of adaptation measures to tackle potential increases in climate-related extreme events. Also, methodological choices about the treatment of disparate, incommensurable impacts are often decisive for policy decisions. This document presents a series of what we refer to as critical issues for climate mitigation and adaptation policy analysis, involving overarching choices that affect multiple areas of expert analysis, and in particular the socio-economic assessments of climate policies. The following pages identify key issues for a comprehensive and realistic economic analysis of climate policies, present a few major options for answering those issues, and recommend a preferred course of action or option for analysts to consider (akin to what some refer to as "new economic thinking"). The issue of risk and uncertainty has been addressed in a separate supporting guidance document, due to its overriding importance and specific inter-disciplinary profile (available on the website of the MCA4climate initiative: www.mca4climate.info). In addition, some practical implementation aspects of the issues discussed below have been provided in Annex 1 at the end of this document. Some of the topics addressed here may be more amenable to qualitative than to quantitative analysis; potential examples include the valuation of non-market "goods" such as human health and environmental protection, and the goal of intergenerational equity. It is nonetheless important to understand the implications of both quantitative and qualitative approaches to these issues, since both approaches are often raised in the discussion of climate policy. The guiding principles underpinning the overall MCA4climate approach

Enhanced transmission versus localization of a light pulse by a subwavelength metal slit: Can the pulse have both characteristics?

The existence of resonant enhanced transmission and collimation of light waves by subwavelength slits in metal films [for example, see T.W. Ebbesen et al., Nature (London) 391, 667 (1998) and H.J. Lezec et al., Science, 297, 820 (2002)] leads to the basic question: Can a light be enhanced and simultaneously localized in space and time by a subwavelength slit? To address this question, the spatial distribution of the energy flux of an ultrashort (femtosecond) wave-packet diffracted by a subwavelength (nanometer-size) slit was analyzed by using the conventional approach based on the Neerhoff and Mur solution of Maxwell's equations. The results show that a light can be enhanced by orders of magnitude and simultaneously localized in the near-field diffraction zone at the nm- and fs-scales. Possible applications in nanophotonics are discussed.Comment: 5 figure

A typology of community flood resilience

Flood risk is increasing worldwide and there is a growing need to better understand the co-benefits of investments in disaster resilience. Utilizing a multinational community flood resilience dataset, this paper takes a systems approach to understanding community-level flood resilience. Using a cluster analysis and bivariate correlation methods, we develop a typology of community flood resilience capacity based on community characteristics and five capitals (human, financial, natural, physical, and social). Our results reinforce the importance of context-specific policymaking and give recommendations of four distinct clusters to investigate the relationship between flood resilience and prevailing development conditions. We especially find that communities with higher interactions between their capital capacities tend to have higher flood resilience levels. Additionally, there are indications that stronger interactions between community capacities can help to induce multiple co-benefits when investing in disaster resilience. Our results also have important policy implications on the individual community level. For example, based on our results, we suggest that communities with lower flood resilience capacities and interactions can best build resilience on leveraging their relatively higher human capital capacities to strengthen the financial and social capitals. Negative effects might happen for urban communities when co-benefits of natural and physical capital are not fully integrated. The highest flood resilience capacity is found in communities with a well-balanced household income distribution which is likely a contributing factor to the importance of financial capital for this cluster. Our results emphasize the importance of an integrative approach to management when implementing systematic flood disaster resilience metrics and development measures

Fiscal resilience challenged

The GAR Risk Atlas contributes to unveiling the hidden risk in national economies and their urban centres. Building on a multi-year effort by a consortium of leading scientific institutions coordinated by UNISDR, it provides a global vision of where and how disaster risk can undermine development. It estimates the probability of future disaster losses in the built environment for five major hazards (earthquakes, tsunamis, riverine floods, and tropical cyclones - winds and storm surge) and for every country and territory in the world and represents the results using robust risk metrics such as Average Annual Loss (AAL) and Probable Maximum Loss (PML). The GAR Risk Atlas (special report of the GAR series) presents the fully updated results of the global risk assessment in a visually appealing and innovative manner

Scenarios as the basis for assessment of mitigation and adaptation

The possibilities and need for adaptation and mitigation depends on uncertain future developments with respect to socio-economic factors and the climate system. Scenarios are used to explore the impacts of different strategies under uncertainty. In this chapter, some scenarios are presented that are used in the ADAM project for this purpose. One scenario explores developments with no mitigation, and thus with high temperature increase and high reliance on adaptation (leading to 4oC increase by 2100 compared to pre-industrial levels). A second scenario explores an ambitious mitigation strategy (leading to 2oC increase by 2100 compared to pre-industrial levels). In the latter scenario, stringent mitigation strategies effectively reduces the risks of climate change, but based on uncertainties in the climate system a temperature increase of 3oC or more cannot be excluded. The analysis shows that, in many cases, adaptation and mitigation are not trade-offs but supplements. For example, the number of people exposed to increased water resource stress due to climate change can be substantially reduced in the mitigation scenario, but even then adaptation will be required for the remaining large numbers of people exposed to increased stress. Another example is sea level rise, for which adaptation is more cost-effective than mitigation, but mitigation can help reduce damages and the cost of adaptation. For agriculture, finally, only the scenario based on a combination of adaptation and mitigation is able to avoid serious climate change impacts

Quantifying community resilience to riverine hazards in Bangladesh

Every year, 30–70% of Bangladesh is inundated with flood waters, which combined with erosion, affect between 10 and 70 million people annually. Rural riverine communities in Bangladesh have long been identified as some of the poorest populations, most vulnerable to riverine hazards. However, these communities have, for generations, also developed resilience strategies – considered as the combination of absorptive, adaptive, and transformative approaches – to manage significant flooding and erosion. It is not clear whether such existing strategies are sufficient to generate resilience in the face of increasing hazards and growing pressures for land. In this study, we quantify community resilience to flooding and erosion of 35 of the most poverty-stricken and exposed communities in riverine Bangladesh by applying the systematic resilience measurement framework provided by the Flood Resilience Measurement for Communities tool. The low levels of resilience observed in the riverine communities, as well as their continued focus on enhancing absorptive capacities are alarming, especially in the face of growing climate threats and continued population growth. Innovative transformative responses are urgently required in riverine Bangladesh, which align with and complement ongoing community-centred efforts to enhance rural resilience to riverine hazards

Adaptation to Climate Change: Why is it Needed and How Can it be Implemented?

This is the 3rd study to be published in the CEPS Policy Brief series from ongoing research being carried out for the EU-funded ADAM project (ADaptation And Mitigation strategies: supporting European climate policy). Following an introduction to the aims and objectives of the ADAM project, section 2 sets out the rationales for public policy related to adaptation to the impacts of climatic change in the EU. Section 3 provides evidence from a number of stakeholders and sketches the perception of various actors towards the role of European adaptation policies and climate proofing of sectoral policies. Section 4 on the economics of adaptation argues that the economic impacts of climate change will mainly be reduced by private and autonomous response, while principal challenges are with adaptation needs that require collective action and public engagement, including public finance. Section 5 assesses monetary and socioeconomic risks from extreme weather events in Europe and points to the evidence of rising losses due to weather extremes whilst important knowledge gaps remain to project future risks. And the final section (6) deals with different concepts of uncertainties surrounding climate change and climate variability, and argues for adaptive measures to be sufficiently flexible to allow recalibration as uncertainties are reduced with time