Spatial analysis of mean temperature trends in Spain over the period 1961–2006

The spatial distribution of recent mean temperature trends over Spain during the period 1961–2006 at monthly, seasonal and annual time scale is carried out in this study by applying various statistical tools to data from 473 weather stations. The magnitude of trends was derived from the slopes of the linear trends using ordinary least-square fitting. The non-parametric Mann–Kendall test was used to determine the statistical significance of trends. Maps of surface temperature trends were generated by applying a geostatistical interpolation technique to visualize the detected tendencies. This study reveals that temperature has generally increased during all months and seasons of the year over the last four decades. More than 60% of whole Spain has evidenced significant positive trends in March, June, August, spring and summer. This percentage diminishes around 40% in April, May and December. Annual temperature has significantly risen in 100% of Spain of around 0.1–0.2 °C/decade according to the Fourth Assessment Report of the IPCC.