Mechanisms of variability in decadal sea-level trends in the Baltic Sea over the 20th century

Coastal sea-level trends in the Baltic Sea display decadal-scale variations around a long-term centennial trend. In this study, we analyse the spatial and temporal characteristics of the decadal trend variations and investigate the links between coastal sea-level trends and atmospheric forcing on a decadal timescale. For this analysis, we use monthly means of sea-level and climatic data sets. The sea-level data set is composed of long tide gauge records and gridded sea surface height (SSH) reconstructions. Climatic data sets are composed of sea-level pressure, air temperature, precipitation, evaporation, and climatic variability indices. The analysis indicates that atmospheric forcing is a driving factor of decadal sea-level trends. However, its effect is geographically heterogeneous. This impact is large in the northern and eastern regions of the Baltic Sea. In the southern Baltic Sea area, the impacts of atmospheric circulation on decadal sea-level trends are smaller. To identify the influence of the large-scale factors other than the effect of atmospheric circulation in the same season on Baltic Sea sea-level trends, we filter out the direct signature of atmospheric circulation for each season separately on the Baltic Sea level through a multivariate linear regression model and analyse the residuals of this regression model. These residuals hint at a common underlying factor that coherently drives the decadal sea-level trends in the whole Baltic Sea. We found that this underlying effect is partly a consequence of decadal precipitation trends in the Baltic Sea basin in the previous season. The investigation of the relation between the AMO index and sea-level trends implies that this detected underlying factor is not connected to oceanic forcing driven from the North Atlantic region

Servicios sociales en el contexto migratorio

Este artículo se centra en la legislación, procedimientos y servicios referentes a los inmigrantes, los refugiados y los solicitantes de asilo político en los E.E.U.U., particularmente en la región del Suroeste. El artículo ofrece un bosquejo histórico de las peculiaridades coloniales y post-coloniales de esta región, en especial de aquellas que afectan la situación actual de los inmigrantes. Se incluyen también definiciones claves de las categorías establecidas por el Servicio de Inmigración para la variedad de personas que residen en los E.E.U.U.. Estas categorías determinan el status socio-político y legal de estas personas y sus derechos a servicios. Metodológicamente, el artículo se basa en la literatura disciplinaria y periodística y en visitas de campo a agencias sociales que trabajan en este ámbito. Los autores finalizan la monografia con un análisis de los aspectos positivos y problemáticos de la red de servicios sociales accesibles a los nuevos residentes y con recomendaciones para la mejoría de esa red.This article focuses on the legislative and procedural issues that affect the lives of immigrants, refugees and asylum-seekers in the USA, particularly in the region of the Southwest. An overview of the unique colonial and postcolonial features of this region is provided. The authors discuss how the historical and cultural characteristics of the area continue to affect the situation of current immigrants. Definitions of the basic categories established by the Immigration and Naturalization Service for the diverse populations that seek entry or reside in the USA are included. These categories determine the legal and socio- political status of these persons, including their elegibility for social services. The authors draw from the current social science literature and from press coverage of the issues; field visits to social agencies that serve immigrant populations were also used to supplement the accounts. Recommendations for the improvement of the network of services that affect newcomers to the U.S. are offered in the conclusions. Implications for other countries facing similar quandaries are drawn

Will We Build A Wall? Fear of Mexican/Latino Immigration in U.S. History

A presidential election was won on the strength of a nativist philosophy which asserts that the U.S. must build a wall of separation with its closest neighbor to the South. The current president has voiced not only his frustration and prejudices but the nativist sentiments of the public. The emphasis on “building the wall” and the antagonism expressed towards Mexico have deepened the centuries-old sense of fear and separation felt by members of the Mexican/Latino immigrant group. Can we look at history in search of plausible explanations? This paper examines past and contemporary reasons that might explain the observable antagonism to the Mexican/Latino population in the U.S. today

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]

Detection of human influence on a new, validated 1500-Year temperature reconstruction

Climate records over the last millennium place the twentieth-century warming in a longer historical context. Reconstructions of millennial temperatures show a wide range of variability, raising questions about the reliability of currently available reconstruction techniques and the uniqueness of late-twentieth-century warming. A calibration method is suggested that avoids the loss of low-frequency variance. A new reconstruction using this method shows substantial variability over the last 1500 yr. This record is consistent with independent temperature change estimates from borehole geothermal records, compared over the same spatial and temporal domain. The record is also broadly consistent with other recent reconstructions that attempt to fully recover low-frequency climate variability in their central estimate. High variability in reconstructions does not hamper the detection of greenhouse gas-induced climate change, since a substantial fraction of the variance in these reconstructions from the beginning of the analysis in the late thirteenth century to the end of the records can be attributed to external forcing. Results from a detection and attribution analysis show that greenhouse warming is detectable in all analyzed high-variance reconstructions (with the possible exception of one ending in 1925), and that about a third of the warming in the first half of the twentieth century can be attributed to anthropogenic greenhouse gas emissions. The estimated magnitude of the anthropogenic signal is consistent with most of the warming in the second half of the twentieth century being anthropogenic

Self-organizing maps identify windows of opportunity for seasonal European summer predictions

We combine a machine learning method and ensemble climate predictions to investigate windows of opportunity for seasonal predictability of European summer climate associated with the North Atlantic jet stream. We particularly focus on the impact of North Atlantic spring sea surface temperatures (SST) on the four dominant atmospheric teleconnections associated with the jet stream: the summer North Atlantic Oscillation (NAO) in positive and negative phases, the Atlantic Ridge (At. Ridge), and Atlantic Low (At. Low). We go beyond standard forecast practices by not only identifying these atmospheric teleconnections and their SST precursors but by making use of these identified precursors in the analysis of a dynamical forecast ensemble. Specifically, we train the neural network-based classifier Self-Organizing Maps (SOM) with ERA-20C reanalysis and combine it with model simulations from the Max Planck Institute Earth System Model in mixed resolution (MPI-ESM-MR). We use two different sets of 30-member hindcast ensembles initialized every May, one for training and evaluation between 1902 and 2008, and one for verification between 1980–2016, respectively. Among the four summer atmospheric teleconnections analyzed here, we find that At. Ridge simulated by MPI-ESM-MR shows the best agreement with ERA-20C, thereby representing with its occurrence windows of opportunity for skillful summer predictions. Conversely, At. Low shows the lowest agreement, which might limit the model skill for early warning of warmer than average summers. In summary, we find that spring SST patterns identified with a SOM analysis can be used to guess the dominant summer atmospheric teleconnections at initialization and guide a sub-selection of potential skillful ensemble members. This holds especially true for At. Ridge and At. Low and is unclear for summer NAO. We show that predictive skill in the selected ensemble exceeds that of the full ensemble over regions in the Euro-Atlantic domain where spring SST significantly correlates with summer sea level pressure (SLP). In particular, we find a significant improvement in predictive skill for SLP, geopotential height at 500 hPa, and 2 m temperature at 3–4 months lead time over Scandinavia, which is robust among the two sets of hindcast ensembles. Copyright © 2022 Carvalho-Oliveira, Borchert, Zorita and Baehr