Preface: Forecast and projection in climate scenario of Mediterranean intense events: uncertainties and propagation on environment (the MEDUP project)

The Mediterranean basin is a particularly vulnerable region to climate change, partly due to its quite unique character that results both from physiographic conditions and societal development. The region features indeed a near-closed sea surrounded by very urbanised littorals and mountains from which numerous rivers originate. This results in a lot of interactions and feedbacks between oceanic-atmospheric-hydrological processes that play a predominant role on climate and extreme events that frequently cause heavy dam- ages and human losses in the Mediterranean ...

Preface: Extreme events induced by weather and climate change: evaluation, forecasting and proactive planning

This special issue of Natural Hazards and Earth System Sciences (NHESS) contains eight papers presented as oral or poster contributions in the Natural Hazards NH-1.2 session on"Extreme events induced by weather and climate change: evaluation, forecasting and proactive planning", held at the European Geosciences Union (EGU) General Assembly in Vienna, Austria, on 13-18 April 2008. The aim of the session was to provide an international forum for presenting new results and for discussing innovative ideas and concepts on extreme hydro-meteorological events, including: (i) the assessment of the risk posed by the extreme events, (ii) the expected changes in the frequency and intensity of the events driven by a changing climate and by multiple human- induced causes, (iii) new modelling approaches and original forecasting methods to predict extreme events and their consequences, and (iv) strategies for hazard mitigation and risk reduction, and for a improved adaptation to extreme hydro-meteorological events ...

Assessing trends in insured losses from floods in Spain 1971-2008

Economic impacts from floods have been increasing over recent decades, a fact often attributed to a changing climate. On the other hand, there is now a significant body of scientific scholarship all pointing towards increasing concentrations and values of assets as the principle cause of the increasing cost of natural disasters. This holds true for a variety of perils and across different jurisdictions. With this in mind, this paper examines the time history of insured losses from floods in Spain between 1971 and 2008. It as- sesses whether any discernible residual signal remains after adjusting the data for the increase in the number and value of insured assets over this period of time. Data on insured losses from floods were sourced from Consorcio de Com- pensacíon de Seguros (CCS). Although a public institution, CCS compensates homeowners for the damage produced by floods, and thus plays a role similar to that of a private insurance company. Insured losses were adjusted using two proxy measures: first, changes in the total amount of annual surcharges (premiums) paid by customers to CCS, and secondly, changes in the total value of dwellings per year. The adjusted data reveals no significant trend over the period 1971-2008 and serves again to confirm that at this juncture, societal in- fluences remain the prime factors driving insured and economic losses from natural disasters.

Preface"11th Plinius Conference on Mediterranean Storms"

The EGU Plinius Conference on Mediterranean Storms was established in 1999 within the framework of the Interdisciplinary Working Group on Natural Hazards (IWG-NH) of the former European Geophysical Society (EGS)- since 2002,European Geosciences Union (EGU). Since its advent, the Plinius Conference series has provided a crucial interdisciplinary forum for improving our understanding of hazardous storms over the Mediterranean basin that are capable of producing strong winds, heavy rains, explosive landslides, devastating flash floods and other related extremes ...

Fluctuaciones de la extension del casquete glacial de la isla de Livingston (Shetland del sur) desde 1956 hasta 1996.

A partir de documentos cartográficos e imágenes de satélite se constata un 4,31% de reducción de extensión del casquete glacial de la isla Livingston desde 1956 hasta 1996. Se detecta la influencia de factores locales, fundamentalmente de tipo topogr á fico, que condicionan los avances y retrocesos del frente glacial en los diferentes sectores de la costa y se establece un modelo simple en el que se relaciona la reducción del conjunto del casquete con el calentamiento atmosférico experimentado en los últimos decenios en la zona de la Península Antártica.

Evidence for the influence of the North Atlantic Oscillation on the total ozone column at northern low latitudes and midlatitudes during winter and summer seasons.

The strong influence of the winter North Atlantic Oscillation (NAO) on the total ozone column (TOC) in the Northern Hemisphere has been reported in a number of previous studies. In this study we show that this influence is not restricted to the winter season but is also significant in summer. Especially interesting effects of the summer NAO (SNAO) on the TOC are observed over the eastern Mediterranean region, where a strongly positive SNAO index is related to the creation of a geopotential height-negative anomaly over Greece with maximum amplitude at 200 hPa. Another anomaly was observed west of the Iberian Peninsula with similar effects on the TOC. Analyzing 26 years of Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) data from the equator to midlatitudes (60°) in the Northern Hemisphere, we demonstrate that the SNAO accounts for up to 30% of the TOC variability with a strong latitudinal and longitudinal dependence. Additionally, we obtain significant correlations between the NAO index and the thermal tropopause pressure and also with the geopotential heights at 200 and 500 hPa. Finally, some indirect connections between NAO and the TOC through teleconnections are also discussed.

Cambio climático y diversidad de la flora vascular en las montañas tabulares de Guayana.

Una de las posibles consecuencias del calentamiento global es la extinción de especies de alta montaña por migración ascendente de las condiciones ambientales y pérdida de hábitat, fenómeno que, por el momento, ha sido considerado únicamente en montañas templadas y boreales. Este trabajo analiza la misma situación en montañas tropicales y estima el grado de amenaza de la flora vascular de las cimas de las montañas neotropicales de Guayana, al norte de Sudamérica. Del estudio basado en una muestra de 83 especies, entre aproximadamente el 8 y el 33% de las mismas se encuentran en peligro de extinguirse debido a la desaparición de su hábitat. La mayoría de estas especies son endémicas de Guayana, por lo que su desaparición afectaría a la biodiversidad global.

Estimating 750 years of temperature variations and uncertainties in the Pyrenees by tree-ring reconstructions and climate simulations.

Past temperature variations are usually inferred from proxy data or estimated using general circulation models. Comparisons between climate estimations derived from proxy records and from model simulations help to better understand mechanisms driving climate variations, and also offer the possibility to identify deficiencies in both approaches. This paper presents regional temperature reconstructions based on tree-ring maximum density series in the Pyrenees, and compares them with the output of global simulations for this region and with regional climate model simulations conducted for the target region. An ensemble of 24 reconstructions of May-to-September regional mean temperature was derived from 22 maximum density tree-ring site chronologies distributed over the larger Pyrenees area. Four different tree-ring series standardization procedures were applied, combining two detrending methods: 300-yr spline and the regional curve standardization (RCS). Additionally, different methodological variants for the regional chronology were generated by using three different aggregation methods. Calibration verification trials were performed in split periods and using two methods: regression and a simple variance matching. The resulting set of temperature reconstructions was compared with climate simulations performed with global (ECHO-G) and regional (MM5) climate models. The 24 variants of May-to-September temperature reconstructions reveal a generally coherent pattern of inter-annual to multi-centennial temperature variations in the Pyrenees region for the last 750 yr. However, some reconstructions display a marked positive trend for the entire length of the reconstruction, pointing out that the application of the RCS method to a suboptimal set of samples may lead to unreliable results. Climate model simulations agree with the tree-ring based reconstructions at multi-decadal time scales, suggesting solar variability and volcanism as the main factors controlling preindustrial mean temperature variations in the Pyrenees. Nevertheless, the comparison also highlights differences with the reconstructions, mainly in the amplitude of past temperature variations and in the 20th century trends. Neither proxy-based reconstructions nor model simulations are able to perfectly track the temperature variations of the instrumental record, suggesting that both approximations still need further improvements.

A look to the HyMeX program (Una mirada al programa HyMeX)

The international HyMeX (Hydrological Mediterranean Experiment) program aims to improve our understanding of the water cycle in the Mediterranean, using a multidisciplinary and multiscale approach and with emphasis on extreme events. This program will improve our understanding and our predictive ability of hydrometeorological hazards including their evolution within the next century. One of the most important results of the program will be its observational campaigns, which will greatly improve the data available, leading to significant scientific results. The interest of the program for the Spanish research groups is described, as the active participation of some of them in the design and execution of the observational activities. At the same time, due to its location, Spain is key to the program, being a good observation platform. HyMeX will enrich the work of the Spanish research groups, it will improve the predictive ability of the weather services, will help us to have a better understanding of the impacts of hydrometeorological extremes on our society and will lead to better strategies for adapting to climate change.

El canvi climàtic posa en perill el cafè i el cacau

PER A MOLTES PERSONES, beure cafè i menjar xocolata és un autèntic plaer. Tant les plantes de cafè com les de cacau es cultiven en unes zones molt concretes de la Terra, als cinturons tropicals, i en teoria representen una font de riquesa per als països productors. Tanmateix, la demanda creixent, combinada amb els efectes del canvi climàtic i les desigualtats econòmiques entre productors i consumidors, posen en perill aquests cultius. Així ho indiquen dos estudis publicats a la revista Plos One i un altre a Current Biology, que suggereixen que per mantenir la productivitat actual cal incrementar la diversitat genètica d"aquestes plantes i afavorir un model de comerç just.

Las entidades sub-nacionales en Norteamérica y la lucha contra el cambio climático: desarrollo normativo y vinculación de sistemas de comercio de derechos de emisión

[spa] Mientras que en Europa la interdependencia y la dimensión transfronteriza de las cuestiones ligadas al cambio climático ha facilitado una cierta"continentalización" de la gestión de este fenómeno, favorecida por el carácter intergubernamental de las medidas que se adoptan en el marco de la Unión Europea, al otro lado del Atlántico la transversalidad de este mismo fenómeno explica la necesidad de que, ante las limitaciones del marco regional, se pongan en marcha mecanismos que faciliten la intervención no sólo estatal sino también de las entidades sub-nacionales. En este sentido, la ausencia de la acción federal tanto en Estados Unidos como en Canadá ha comportado un mayor desarrollo de la acción de las entidades sub-nacionales, que han tomado el liderazgo en la lucha contra el cambio climático. Son estas medidas las que se han visualizado en el escenario internacional. Ello ha favorecido el establecimiento de mecanismos de coordinación de la acción de estas entidades sub-nacionales en el seno de redes transnacionales, que han ido adquiriendo una mayor relevancia en la implementación del Convenio Marco sobre el Cambio Climático y del Protocolo de Kyoto, particularmente en relación a uno de sus instrumentos, el comercio de los derechos de emisión de gases de efecto invernadero. En este contexto, la futura vinculación de los sistemas de comercio de derechos de emisión de gases de efecto invernadero en Norteamérica con el sistema de la Unión Europea presenta diversos retos de carácter material y formal.

Vulnerability of stream biota to climate change in mediterranean climate regions: a synthesis of ecological responses and conservation challenges

Freshwater species worldwide are experiencing dramatic declines partly attributable to ongoing climate change. It is expected that the future effects of climate change could be particularly severe in mediterranean climate (med-) regions, which host many endemic species already under great stress from the high level of human development. In this article, we review the climate and climate-induced changes in streams of med-regions and the responses of stream biota, focusing on both observed and anticipated ecological responses. We also discuss current knowledge gaps and conservation challenges. Expected climate alterations have already been observed in the last decades, and include: increased annual average air temperatures; decreased annual average precipitation; hydrologic alterations; and an increase in frequency, intensity and duration of extreme events, such as floods, droughts and fires. Recent observations, which are concordant with forecasts built, show stream biota of med-regions when facing climate changes tend to be displaced towards higher elevations and upper latitudes, communities tend to change their composition and homogenize, while some life-history traits seem to provide biota with resilience and resistance to adapt to the new conditions (as being short-lived, small, and resistant to low streamflow and desiccation). Nevertheless, such responses may be insufficient to cope with current and future environmental changes. Accurate forecasts of biotic changes and possible adaptations are difficult to obtain in med-regions mainly because of the difficulty of distinguishing disturbances due to natural variability from the effects of climate change, particularly regarding hydrology. Long-term studies are needed to disentangle such variability and improve knowledge regarding the ecological responses and the detection of early warning signals to climate change. Investments should focus on taxa beyond fish and macroinvertebrates, and in covering the less studied regions of Chile and South Africa. Scientists, policy makers and water managers must be involved in the climate change dialogue because the freshwater conservation concerns are huge.

The summer North Atlantic Oscillation in CMIP3 models and related uncertainties in projected summer drying in Europe

This paper discusses uncertainties in model projections of summer drying in the Euro-Mediterranean region related to errors and uncertainties in the simulation of the summer NAO (SNAO). The SNAO is the leading mode of summer SLP variability in the North Atlantic/European sector and modulates precipitation not only in the vicinity of the SLP dipole (northwest Europe) but also in the Mediterranean region. An analysis of CMIP3 models is conducted to determine the extent to which models reproduce the signature of the SNAO and its impact on precipitation and to assess the role of the SNAO in the projected precipitation reductions. Most models correctly simulate the spatial pattern of the SNAO and the dry anomalies in northwest Europe that accompany the positive phase. The models also capture the concurrent wet conditions in the Mediterranean, but the amplitude of this signal is too weak, especially in the east. This error is related to the poor simulation of the upper-level circulation response to a positive SNAO, namely the observed trough over the Balkans that creates potential instability and favors precipitation. The SNAO is generally projected to trend upwards in CMIP3 models, leading to a consistent signal of precipitation reduction in NW Europe, but the intensity of the trend varies greatly across models, resulting in large uncertainties in the magnitude of the projected drying. In the Mediterranean, because the simulated influence of the SNAO is too weak, no precipitation increase occurs even in the presence of a strong SNAO trend, reducing confidence in these projections.

Quantifying seasonality along a latitudinal gradient: from stream temperature to growth of invasive mosquitofish

Most ecosystems undergo substantial variation over the seasons, ranging from changes in abiotic features, such as temperature, light and precipitation, to changes in species abundance and composition. How seasonality varies along latitudinal gradients is not well known in freshwater ecosystems, despite being very important in predicting the effects of climate change and in helping to advance ecological understanding. Stream temperature is often well correlated with air temperature and influences many ecosystem features such as growth and metabolism of most aquatic organisms. We evaluated the degree of seasonality in ten river mouths along a latitudinal gradient for a set of variables, ranging from air and water temperatures, to physical and chemical properties of water and growth of an invasive fish species (eastern mosquitofish, Gambusia holbrooki ). Our results show that although most of the variation in air temperature was explained by latitude and season, this was not the case for water features, including temperature, in lowland Mediterranean streams, which depended less on season and much more on local factors. Similarly, although there was evidence of latitude-dependent seasonality in fish growth, the relationship was nonlinear and weak and the significant latitudinal differences in growth rates observed during winter were compensated later in the year and did not result in overall differences in size and growth. Our results suggest that although latitudinal differences in air temperature cascade through properties of freshwater ecosystems, local factors and complex interactions often override the water temperature variation with latitude and might therefore hinder projections of species distribution models and effects of climate change

The effects of depleted, current and elevated growth [CO2] in wheat are modulated by water availability

Drought is the main constraint on wheat yield in Mediterranean conditions. The photosynthesis, chlorophyll fluorescence and plant growth parameters of durum wheat (Triticum turgidum, L. var. durum) were compared at three [CO2] (i.e., depleted 260 ppm, current 400ppm and elevated 700 ppm) in plants subjected to twowater regimes (i.e.,well-wateredWW, and mildwater stress by drought orwater deficit WS), during pre-anthesis, post-anthesis and the end of grain filling. We showed that [CO2] effects on plants are modulated by water availability. Plants at depleted [CO2] showed photosynthetic acclimation (i.e., up-regulation) and reduced plant biomass and Harvest Index, but depleted [CO2] combined with WS has a more negative impact on plants with decreases in C assimilation and biomass. Plants at elevated [CO2] had decreased plant growth and photosynthesis in response to a down-regulation mechanism resulting from a decrease in Rubisco and N content, but plants exposed to a combination of elevated [CO2] and WS were the most negatively affected (e.g., on plant biomass).