Política nacional de vivienda: los impactos esperados en base a la revisión de la literatura académica antes y después del 2008

Las políticas de vivienda están al centro de la plataforma de políticas de casi cualquier país, por lo que es necesario conocer cuándo, cómo y por qué llevar a cabo cada una. En esta tesis se analizan las distintas opciones y sus impactos en salud, educación, riqueza, desarrollo humano y compromiso cívico, teniendo en cuenta cómo cambiaron las conclusiones en la última década. Metodologías, datos y una crisis hipotecaria permitieron cuestionar algunos supuestos de la literatura académica relativa al sector. Para Argentina, este cambio permite conocer cómo mejorar y rediseñar una historia de políticas que no logró reducir el déficit habitacional en el país. El trabajo provee elementos para contribuir al actual Plan Nacional de Vivienda en su objetivo central de reducir el déficit habitacional, principalmente en pos de una correcta evaluación de los programas y propuestas de modificaciones en el diseño de los programas de crédito y alquiler

European summer temperatures since Roman times

The spatial context is criticalwhen assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding their frequency and severity in a long-term perspective. Recent international initiatives have expanded the number of high-quality proxy-records and developed new statistical reconstruction methods. These advances allow more rigorous regional past temperature reconstructions and, in turn, the possibility of evaluating climate models on policy-relevant, spatiotemporal scales. Here we provide a new proxy-based, annually-resolved, spatial reconstruction of the European summer (June-August) temperature fields back to 755 CE based on Bayesian hierarchical modelling (BHM), together with estimates of the European mean temperature variation since 138 BCE based on BHM and composite-plus-scaling (CPS). Our reconstructions compare well with independent instrumental and proxy-based temperature estimates, but suggest a larger amplitude in summer temperature variability than previously reported. Both CPS and BHM reconstructions indicate that the mean 20th century European summer temperature was not significantly different from some earlier centuries, including the 1st, 2nd, 8th and 10th centuries CE. The 1st century (in BHM also the 10th century) may even have been slightly warmer than the 20th century, but the difference is not statistically significant. Comparing each 50 yr period with the 1951-2000 period reveals a similar pattern. Recent summers, however, have been unusually warm in the context of the last two millennia and there are no 30 yr periods in either reconstruction that exceed the mean average European summer temperature of the last 3 decades (1986-2015 CE). A comparison with an ensemble of climate model simulations suggests that the reconstructed European summer temperature variability over the period 850-2000 CE reflects changes in both internal variability and external forcing on multi-decadal time-scales. For pan-European temperatures we find slightly better agreement between the reconstruction and the model simulations with high-end estimates for total solar irradiance. Temperature differences between the medieval period, the recent period and the Little Ice Age are larger in the reconstructions than the simulations. This may indicate inflated variability of the reconstructions, a lack of sensitivity and processes to changes in external forcing on the simulated European climate and/or an underestimation of internal variability on centennial and longer time scales

200years of European temperature variability: insights from and tests of the proxy surrogate reconstruction analog method

Spatially resolved climate reconstructions are commonly derived from long instrumental series and proxy data via linear regression based approaches that use the main modes of the climate system. Such reconstructions have been shown to underestimate climate variability and are based upon the assumption that the main modes of climate variability are stationary back in time. Climate models simulate physically consistent climate fields but cannot be taken to represent the real past climate trajectory because of their necessarily simplified scope and chaotic internal variability. Here, we present sensitivity tests of, and a 200-year temperature reconstruction from, the PSR (Proxy Surrogate Reconstruction) method. This method simultaneously capitalizes on the individual strengths of instrumental/proxy data based reconstructions and model simulations by selecting the model states (analogs) that are most similar with proxy/instrumental data available at specific places and specific moments of time. Sensitivity experiments reveal an optimal PSR configuration and indicate that 6,500 simulation years of existing climate models provide a sufficient pool of possible analogs to skillfully reconstruct monthly European temperature fields during the past 200years. Reconstruction verification based upon only seven instrumental stations indicates potential for extensions back in time using sparse proxy data. Additionally the PSR method allows evaluation of single time series, in this case the homogeneity of instrumental series, by identifying inconsistencies with the reconstructed climate field. We present an updated European temperature reconstruction including newly homogenized instrumental records performed with the computationally efficient PSR method that proves to capture the total variance of the targe

The making of the New European Wind Atlas - Part 1: model sensitivity

This is the first of two papers that document the creation of the New European Wind Atlas (NEWA). It describes the sensitivity analysis and evaluation procedures that formed the basis for choosing the final setup of the mesoscale model simulations of the wind atlas. The suitable combination of model setup and parameterizations, bound by practical constraints, was found for simulating the climatology of the wind field at turbine-relevant heights with the Weather Research and Forecasting (WRF) model. Initial WRF model sensitivity experiments compared the wind climate generated by using two commonly used planetary boundary layer schemes and were carried out over several regions in Europe. They confirmed that the most significant differences in annual mean wind speed at 100 m a.g.l. (above ground level) mostly coincide with areas of high surface roughness length and not with the location of the domains or maximum wind speed. Then an ensemble of more than 50 simulations with different setups for a single year was carried out for one domain covering northern Europe for which tall mast observations were available. We varied many different parameters across the simulations, e.g. model version, forcing data, various physical parameterizations, and the size of the model domain. These simulations showed that although virtually every parameter change affects the results in some way, significant changes in the wind climate in the boundary layer are mostly due to using different physical parameterizations, especially the planetary boundary layer scheme, the representation of the land surface, and the prescribed surface roughness length. Also, the setup of the simulations, such as the integration length and the domain size, can considerably influence the results. We assessed the degree of similarity between winds simulated by the WRF ensemble members and the observations using a suite of metrics, including the Earth Mover’s Distance (EMD), a statistic that measures the distance between two probability distributions. The EMD was used to diagnose the performance of each ensemble member using the full wind speed and direction distribution, which is essential for wind resource assessment. We identified the most realistic ensemble members to determine the most suitable configuration to be used in the final production run, which is fully described and evaluated

Wet season Mediterranean precipitation variability: influence of large-scale dynamics and trends

Abstract : The influence of the large-scale atmospheric circulation at several tropospheric levels on wet season precipitation over 292 sites across the Mediterranean area is assessed. A statistical downscaling model is designed with an objective methodology based on empirical orthogonal functions and canonical correlation analysis (CCA) and tested by means of cross-validation. In all 30% of the total Mediterranean October to March precipitation variability can be accounted for by the combination of four large-scale geopotential height fields and sea level pressure. The Mediterranean sea surface temperatures seem to be less relevant to explain precipitation variability at interannual time scale. It is shown that interdecadal changes in the first CCA mode are related to variations in the North Atlantic Oscillation index and responsible for comparable time scale variations of the Mediterranean precipitation throughout the twentieth century. The analysis reveals that since the mid-nineteenth century precipitation steadily increased with a maximum in the 1960s and decreased since then. The second half of the twentieth century shows a general downward trend of 2.2mm·month-1·decade-

Comment on "Robustness of proxy-based climate field reconstruction methods" by Michael E. Mann et al.

Mann et al. [2007a] (hereafter M07a) test the climate field reconstruction (CFR) method known as regularized expectation maximization (RegEM) using pseudoproxies derived from millennial simulations of past climate. These simulations were derived from two General Circulation Models (GCMs) driven with natural and anthropogenic forcings: the National Center for Atmospheric Research Climate System Model (CSM) [Boville et al., 2001] and the Hamburg Atmosphere-Ocean Coupled Circulation Model (ECHO-g) [Legutke and Voss, 1999]. There has been some discussion about the amplitude of millennial changes in simulations from these two GCMs [Goosse et al., 2005; Mann et al., 2005; Osborn et al., 2006; González-Rouco et al., 2006], particularly with regard to how it may impact the assessment of CFR methods in pseudoproxy experiments [Mann et al., 2005; Mann, 2007; Zorita et al., 2007; Mann et al., 2007a, 2007b]

Regional surface temperature simulations over the Iberian Peninsula: evaluation and climate projections

The realism of a specifc confguration of the WRF Regional Climate Model (RCM) to represent the observed temperature evolution over the Iberian Peninsula (IP) in the 1971–2005 period has been analyzed. The E-OBS observational dataset was used for this purpose. Also, the added value of the WRF simulations with respect to the IPSL Earth System Model (ESM) used to drive the WRF RCM was evaluated. In general, WRF presents lower temperatures than in the observations (negative biases) over the IP. These biases are comparatively larger than those of the driving ESM. Once the biases are corrected, WRF provides an added value in terms of a higher spatial representation. WRF introduces more variability in some regions in comparison to gridded observation. Warming trends according to the observations are also well represented by the RCM. In the second part of this study, the projections of future climate performed with both the ESM and the RCM were evaluated for the RCP4.5 and RCP8.5 scenarios during the 21st century. Although both models simulate temperature increases, the RCM simulates a smaller warming than the ESM after the mid-21st century, except for winter. Using the WRF model, the maximum temperature increase reaches 6 ◦C and 3 ◦C for RCP8.5 and RCP4.5 in the south east of the Iberian Peninsula by the end of the 21st century, respectively

Borehole climatology: a discussion based on contributions from climate modeling

Progress in understanding climate variability through the last millennium leans on simulation and reconstruction efforts. Exercises blending both approaches present a great potential for answering questions relevant both for the simulation and reconstruction of past climate, and depend on the specific peculiarities of proxies and methods involved in climate reconstructions, as well as on the realism and limitations of model simulations. This paper explores research specifically related to paleoclimate modeling and borehole climatology as a branch of climate reconstruction that has contributed significantly to our knowledge of the low frequency climate evolution during the last five centuries. The text flows around three main issues that group most of the interaction between model and geothermal efforts: the use of models as a validation tool for borehole climate reconstructions; comparison of geothermal information and model simulations as a means of either model validation or inference about past climate; and implications of the degree of realism on simulating subsurface climate on estimations of future climate change. The use of multi-centennial simulations as a surrogate reality for past climate suggests that within the simplified reality of climate models, methods and assumptions in borehole reconstructions deliver a consistent picture of past climate evolution at long time scales. Comparison of model simulations and borehole profiles indicate that borehole temperatures are responding to past external forcing and that more realism in the development of the soil model components in climate models is desirable. Such an improved degree of realism is important for the simulation of subsurface climate and air-ground interaction; results indicate it could also be crucial for simulating the adequate energy balance within climate change scenario experiments

Influence of radiative forcing factors on ground–air temperature coupling during the last millennium: implications for borehole climatology

Past climate variations may be uncovered via reconstruction methods that use proxy data as predictors. Among them, borehole reconstruction is a well-established technique to recover the long-term past surface air temperature (SAT) evolution. It is based on the assumption that SAT changes are strongly coupled to ground surface temperature (GST) changes and transferred to the subsurface by thermal conduction. We evaluate the SAT–GST coupling during the last millennium (LM) using simulations from the Community Earth System Model LM Ensemble (CESM-LME). The validity of such a premise is explored by analyzing the structure of the SAT–GST covariance during the LM and also by investigating the evolution of the long-term SAT–GST relationship. The multiple and single-forcing simulations in the CESM-LME are used to analyze the SAT–GST relationship within different regions and spatial scales and to derive the influence of the different forcing factors on producing feedback mechanisms that alter the energy balance at the surface. The results indicate that SAT–GST coupling is strong at global and above multi-decadal timescales in CESM-LME, although a relatively small variation in the long-term SAT–GST relationship is also represented. However, at a global scale such variation does not significantly impact the SAT–GST coupling, at local to regional scales this relationship experiences considerable long-term changes mostly after the end of the 19th century. Land use land cover changes are the main driver for locally and regionally decoupling SAT and GST, as they modify the land surface properties such as albedo, surface roughness and hydrology, which in turn modifies the energy fluxes at the surface. Snow cover feedbacks due to the influence of other external forcing are also important for corrupting the long-term SAT–GST coupling. Our findings suggest that such local and regional SAT–GST decoupling processes may represent a source of bias for SAT reconstructions from borehole measurement, since the thermal signature imprinted in the subsurface over the affected regions is not fully representative of the long-term SAT variations.Ministerio de Industria, Comercio y Competitividad (FPI grant no. BES-2015-075019)Versión del editor3,50

A Pacific Centennial Oscillation Predicted by Coupled GCMs

Internal climate variability at the centennial time scale is investigated using long control integrations from three state-of-the-art global coupled general circulation models. In the absence of external forcing, all three models produce centennial variability in the mean zonal sea surface temperature (SST) and sea level pressure (SLP) gradients in the equatorial Pacific with counterparts in the extratropics. The centennial pattern in the tropical Pacific is dissimilar to that of the interannual El Niño–Southern Oscillation (ENSO), in that the most prominent expression in temperature is found beneath the surface of the western Pacific warm pool. Some global repercussions nevertheless are analogous, such as a hemispherically symmetric atmospheric wave pattern of alternating highs and lows. Centennial variability in western equatorial Pacific SST is a result of the strong asymmetry of interannual ocean heat content anomalies, while the eastern equatorial Pacific exhibits a lagged, Bjerknes-like response to temperature and convection in the west. The extratropical counterpart is shown to be a flux-driven response to the hemispherically symmetric circulation anomalies emanating from the tropical Pacific. Significant centennial-length trends in the zonal SST and SLP gradients rivaling those estimated from observations and model simulations forced with increasing CO₂ appear to be inherent features of the internal climate dynamics simulated by all three models. Unforced variability and trends on the centennial time scale therefore need to be addressed in estimated uncertainties, beyond more traditional signal-to-noise estimates that do not account for natural variability on the centennial time scale