Spatial and temporal variability of the frequency of extreme daily rainfall regime in the La Plata Basin during the 20th century

We analyzed trends, interdecadal variability, and the quantification of the changes in the frequency of daily rainfall for two thresholds: 0.1 mm and percentile 75th, using high quality daily series from 52 stations in the La Plata Basin (LPB). We observed increases in the annual frequencies in spatially coherent areas. This coherence was more marked in austral summer, autumn, and spring, during which the greatest increases occurred in southern Brazil, especially during extreme events. In winter, the low and middle basins of the Río Uruguay and Río Paraná showed negative trends, some of which were significant. Interdecadal variability is well defined in the region with more pronounced positive jumps west of the basin between 1950 and 2000. This variability was particularly more marked during periods of extreme rainfall in summer, autumn, and spring, unlike in winter when extreme daily rainfall in the lower Rio Paraná basin decreased by up to 60%. The changes in the past century during extreme rainfall produced modifications in the annual rainfall cycle. The annual cycle of both indices was broader during the last period which is mainly explained by the strong decreases in winter.     

Performance of a multi-RCM ensemble for South Eastern South America

The ability of four regional climate models to reproduce the present-day South American climate is examined with emphasis on La Plata Basin. Models were integrated for the period 1991–2000 with initial and lateral boundary conditions from ERA-40 Reanalysis. The ensemble sea level pressure, maximum and minimum temperatures and precipitation are evaluated in terms of seasonal means and extreme indices based on a percentile approach. Dispersion among the individual models and uncertainties when comparing the ensemble mean with different climatologies are also discussed. The ensemble mean is warmer than the observations in South Eastern South America (SESA), especially for minimum winter temperatures with errors increasing in magnitude towards the tails of the distributions. The ensemble mean reproduces the broad spatial pattern of precipitation, but overestimates the convective precipitation in the tropics and the orographic precipitation along the Andes and over the Brazilian Highlands, and underestimates the precipitation near the monsoon core region. The models overestimate the number of wet days and underestimate the daily intensity of rainfall for both seasons suggesting a premature triggering of convection. The skill of models to simulate the intensity of convective precipitation in summer in SESA and the variability associated with heavy precipitation events (the upper quartile daily precipitation) is far from satisfactory. Owing to the sparseness of the observing network, ensemble and observations uncertainties in seasonal means are comparable for some regions and seasons.     

Portfolio screening to support the mainstreaming of adaptation to climate change into development assistance

The need to mainstream adaptation to climate change into development planning and ongoing sectoral decision-making is increasingly recognised, and several bilateral and multilateral development agencies are starting to take an interest. Over the past years at least six development agencies have screened their project portfolios, generally with two goals in mind: (1) to ascertain the extent to which existing development projects already consider climate risks or address vulnerability to climate variability and change, and (2) to identify opportunities for incorporating climate change explicitly into future projects. As each portfolio screening was conducted independently, the broader lessons emerging from the screenings have not been systematically analysed. In this paper we assess the screening activities to date, focusing on both the results and the methods applied. Based on this assessment we identify opportunities for development agencies to expand their current focus on the links between climate and development. Most agencies already consider climate change as a real but uncertain threat to future development, but they have given less thought to how different development patterns might affect vulnerability to climate change. The screenings undertaken have shown the need to take a comprehensive approach to adaptation and its integration into development planning and sectoral decision-making, and a number of policy initiatives have been taken to promote such integration. We provide some initial guidance as to how portfolio screening can be carried out in a way that would allow agencies to assess systematically the relevance of climate change to their ongoing and planned development projects.     

Homeostatic representation for risk decision making: a novel multi-method simulation approach for evacuation under volcanic eruption

Natural Hazards - All decision-making processes are complex and include a high number of variables. Particularly, decisions related to disaster risk reduction despite having an inherent...     

Detection of spatial fluctuations of non-point source fecal pollution in coral reef surrounding waters in southwestern Puerto Rico using PCR-based assays

Human fecal contamination of coral reefs is a major cause of concern. Conventional methods used to monitor microbial water quality cannot be used to discriminate between different fecal pollution sources. Fecal coliforms, enterococci, and human-specific Bacteroides (HF183, HF134), general Bacteroides-Prevotella (GB32), and Clostridium coccoides group (CP) 16S rDNA PCR assays were used to test for the presence of non-point source fecal contamination across the southwestern Puerto Rico shelf. Inshore waters were highly turbid, consistently receiving fecal pollution from variable sources, and showing the highest frequency of positive molecular marker signals. Signals were also detected at offshore waters in compliance with existing microbiological quality regulations. Phylogenetic analysis showed that most isolates were of human fecal origin. The geographic extent of non-point source fecal pollution was large and impacted extensive coral reef systems. This could have deleterious long-term impacts on public health, local fisheries and in tourism potential if not adequately addressed.     

A Sustainability Framework for Enhancing the Long-Term Success of Lulucf Projects

Collateral impacts of land use and land-use change and forestry (LULUCF) projects, especially those concerning social and environmental aspects, have been recognized as important by the Marrakech Accords. The same applies to the necessity of assessing and, if possible, of quantifying the magnitude of these impacts. This article aims to define, clarify and structure the relevant social, economic and environmental issues to be addressed and to give examples of indicators that ought to be included in the planning, design, implementation, monitoring, and ex post evaluation of LULUCF projects. This is being done by providing a conceptual framework for the assessment of the sustainability of such projects that can be used as a checklist when dealing with concrete projects, and that in principle is applicable to both Annex I and non-Annex I countries. Finally, a set of recommendations is provided to further develop and promote the proposed framework.     

Landslide hazard assessment based on Bayesian optimization–support vector machine in Nanping City,China

Natural Hazards - Landslide hazard assessment is critical for preventing and mitigating landslide disasters. The tuning of hyperparameters is of great importance to achieve better accuracy in a...     

Luminous efficacy of global solar radiation on a horizontal surface for overcast and intermediate skies

Summary  In the first part of this research two models for the luminous efficacy of global solar radiation on horizontal surfaces and overcast skies have been developed. The first of these models is developed using a method similar to that proposed by Littlefair (1988). The second model has been obtained from the corresponding illuminance and irradiance models in an, apparently, new approach to the subject. In the second part of this research, a model for the luminous efficacy of global solar radiation for intermediate skies and horizontal surfaces is developed from the corresponding illuminance and irradiance models. The model for intermediate skies is given by the same mathematical function as that of the analogous model for overcast skies, and only the empirical constants change. In all the cases the only independent variables used are the solar altitude and the brightness index. The models proposed in the present paper have been statistically tested, and their prediction accuracy compared with other models available in the scientific literature. Received June 26, 2000 Revised December 9, 2000     

Keeping the forest for the climate's sake: avoiding deforestation in developing countries under the UNFCCC

Abstract

A process for reducing emissions from deforestation in developing countries has been initiated under the UNFCCC. Efforts to agree on a legally binding instrument to halt deforestation have previously failed in other international fora. The magnitude of the social, economic, technical and political complexities underlying deforestation have led to negotiations being challenging. What policy instruments could provide incentives to reduce deforestation, and how could these instruments be framed, under the UNFCCC? This article analyses the advantages and disadvantages of the available alternatives within and outside of the Kyoto Protocol. Staying within the Kyoto framework means low institutional development costs, established but limited incentives for action, and low flexibility. Alternatives outside the Protocol provide higher institutional development costs, uncertainties with regard to the incentives, but greater flexibility. We argue that a separate protocol may be the most viable option, as it could offer the necessary flexibility and avoid some technical and political pitfalls that would be likely to beset new efforts under the Kyoto Protocol. The article also presents the concept of ‘committed forests’ as a means of defining geographically where the reduction of emissions from deforestation can take place.