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

Resonant backward scattering of light by a two-side-open subwavelength metallic slit

The backward scattering of TM-polarized light by a two-side-open subwavelength slit in a metal film is analyzed. We show that the reflection coefficient versus wavelength possesses a Fabry-Perot-like dependence that is similar to the anomalous behavior of transmission reported in the study [Y. Takakura, Phys. Rev. Lett. \textbf{86}, 5601 (2001)]. The open slit totally reflects the light at the near-to-resonance wavelengths. In addition, we show that the interference of incident and resonantly backward-scattered light produces in the near-field diffraction zone a spatially localized wave whose intensity is 10-10$^3$ times greater than the incident wave, but one order of magnitude smaller than the intra-cavity intensity. The amplitude and phase of the resonant wave at the slit entrance and exit are different from that of a Fabry-Perot cavity.Comment: 5 figure

Assessing current and future impacts of climate-related extreme events. The case of Bangladesh

Extreme events and options for managing these risks are receiving increasing attention in research and policy. In order to cost these extremes, a standard approach is to use Integrated Assessment Models with global or regional resolution and represent risk using add-on damage functions that are based on observed impacts and contingent on gradual temperature increase. Such assessments generally find that economic development and population growth are likely to be the major drivers of natural disaster risk in the future; yet, little is said about changes in vulnerability, generally considered a key component of risk. As well, risk is represented by an estimate of average observed impacts using the statistical expectation. Explicitly accounting for vulnerability and using a fuller risk-analytical framework embedded in a simpler economic model, we study the case of Bangladesh, the most flood prone country in the world, in order to critically examine the contribution of all drivers to risk. Specifically, we assess projected changes in riverine flood risk in Bangladesh up to the year 2050 and attempt to quantitatively assess the relative importance of climate change versus socio-economic change in current and future disaster risk. We find that, while flood frequency and intensity, based on regional climate downscaling, are expected to increase, vulnerability, based on observed behaviour in real events over the last 30 years, can be expected to decrease. Also, changes in vulnerability and hazard are roughly of similar magnitudes, while uncertainties are large. Overall, we interpret our findings to corroborate the need for taking a more risk-based approach when assessing extreme events impacts and adaptation - cognizant of the large associated uncertainties and methodological challenges -

A methodological framework to operationalize Climate Risk Management: Managing sovereign climate-related extreme event risk in Austria

Despite considerable uncertainties regarding the exact contribution of anthropogenic climate change to disaster risk, rising losses from extreme events have highlighted the need to comprehensively address climate-related risk. This requires linking climate adaptation to disaster risk management (DRM), leading to what has been broadly referred to as climate risk management (CRM). While this concept has received attention in debate, important gaps remain in terms of operationalizing it with applicable methods and tools for specific risks and decision-contexts. By developing and applying a methodological approach to CRM in the decision context of sovereign risk (flooding) in Austria we test the usefulness of CRM, and based on these insights, inform applications in other decision contexts. Our methodological approach builds on multiple lines of evidence and methods. These comprise of a broad stakeholder engagement process, empirical analysis of public budgets, and risk-focused economic modelling. We find that a CRM framework is able to inform instrumental as well as reflexive and participatory debate in practice. Due to the complex interaction of social-ecological systems with climate risks, and taking into account the likelihood of future contingent climate-related fiscal liabilities increasing substantially as a result of socioeconomic developments and climate change, we identify the need for advanced learning processes and iterative updates of CRM management plans. We suggest that strategies comprising a portfolio of policy measures to reduce and manage climate-related risks are particularly effective if they tailor individual instruments to the specific requirements of different risk layers. (authors' abstract

2nd Consultation Report. Bouncing Forward Sustainably: Pathways to a post-COVID World. Governance for Sustainability

COVID-19 has once again brought the role of governments, and their ability to cooperate and coordinate their actions into the spotlight. It has however also highlighted significant gaps in various areas including the science policy interface; the ability of institutional mechanisms to deal with crises; in the preparedness of global and national science communities and government systems; and in access to reliable, verifiable data to inform decision making. The consultative meetings around this topic draw on lessons learned and experiences from the COVID-19 pandemic to identify effective policy tools and mechanisms that would also give due credence to issues of poverty alleviation, justice, inequalities, and the environment. The goal is to suggest pathways for more robustand responsive governance systems for an uncertain future. This report gives a summary over the discussions in the second consultative meeting that took place online, on July 27, 2020

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

Mechanisms for financing the costs of disasters

This paper provides an overview of disaster risk financing mechanisms, both traditional instruments that share the costs of disastrous events after they happen and ex ante instruments, some innovative, that contractually transfer risks before the events occur. The focus is on developing countries and the most vulnerable within those countries. As recent novel instruments, we describe index-based insurance for farmers and herders, national insurance programs, sovereign instruments for governments and regional risk insurance pools. We present evidence on their benefits, costs and risks, and, finally, address the question: What financial-protection actions could be taken in the next ten years that might reduce the negative impact of disasters occurring up to 2040

National systems for managing the risks from climate extremes and disasters

This chapter assesses how countries are managing current and projected disaster risks, given knowledge of how risks are changing with observations and projections of weather and climate extremes, vulnerability and exposure, and impacts. It focuses on the design of national systems for managing such risks, the roles played by actors involved in the system, and the functions they perform, acknowledging that complementary actions to manage risks are also taken at local and international level