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ABSTRACT Due to imperfections inherent to numerical climate simulations, projections of climate change need to be accompanied with an uncertainty estimate, typically derived from multi-model ensembles. Here, an analysis of regional climate model outputs spread and its temporal evolution is presented, for the European air temperatures simulated over the 21st century. To quantify the overall uncertainty, standard deviation (sd) is used and compared to median absolute deviation and inter-quartile range. The outcomes are shown for annual and seasonal means of air temperature at 2 m, 850 hPa, 700 hPa, 500 hPa and 300 hPa levels, simulated by ENSEMBLES regional climate models for eight geographical areas across Europe. Our results indicate that the estimated uncertainty of simulated air temperature changes over Europe generally increases during the 21st century, and typically decreases with height of the studied vertical level. The influence of driving global climate model on the regional simulation generally increases with height of the studied vertical level. In lower tropospheric levels, the clustering of regional climate models according to driving global climate model is stronger in winter than in summer. [ABSTRACT FROM AUTHOR]

Little use has been made up till now of the concept of climate analogues to link the present and the past, i.e. places whose current climate ('target' locations) is similar to that experienced some decades ago at distant locations ('reference' sites). Indeed, most research up till now has focused on analogues between present and future climates. Here we assess at what period of time the climate at a target station in Europe has reached-or will reach-that of a reference location, and show that the velocity of northward-moving isotherms can attain 15 km year−1. Such displacements in space imply that temperatures at many target sites in Europe have already exceeded those experienced by stations located 300-500 km to the south in the last half-century. Such results can serve to better portray what a rapidly changing climate means to a lay audience, and can provide useful information to the policy-making community. [ABSTRACT FROM AUTHOR]

The article investigates the number of days with snow cover at 268 Alpine climate stations during winter period, from 1961-2000, and its relation with the mean winter temperature over Europe. A physical-statistical model of snow duration, along with hyperbolic tangent function to generate the logistic curve for the snow-temperature relationship were used. Results of the study proves to be valid for the Alpine region and independent against a linear temperature trend. Findings reveal that the snow-temperature sensitivity in the Alpine region is in accordance with earlier estimates for Austria and Switzerland.

Global climate change impacts can already be tracked in many physical and biological systems; in particular, terrestrial ecosystems provide a consistent picture of observed changes. One of the preferred indicators is phenology, the science of natural recurring events, as their recorded dates provide a high-temporal resolution of ongoing changes. Thus, numerous analyses have demonstrated an earlier onset of spring events for mid and higher latitudes and a lengthening of the growing season. However, published single-site or single-species studies are particularly open to suspicion of being biased towards predominantly reporting climate change-induced impacts. No comprehensive study or meta-analysis has so far examined the possible lack of evidence for changes or shifts at sites where no temperature change is observed. We used an enormous systematic phenological network data set of more than 125 000 observational series of 542 plant and 19 animal species in 21 European countries (1971–2000). Our results showed that 78% of all leafing, flowering and fruiting records advanced (30% significantly) and only 3% were significantly delayed, whereas the signal of leaf colouring/fall is ambiguous. We conclude that previously published results of phenological changes were not biased by reporting or publication predisposition: the average advance of spring/summer was 2.5 days decade−1 in Europe. Our analysis of 254 mean national time series undoubtedly demonstrates that species' phenology is responsive to temperature of the preceding months (mean advance of spring/summer by 2.5 days°C−1, delay of leaf colouring and fall by 1.0 day°C−1). The pattern of observed change in spring efficiently matches measured national warming across 19 European countries (correlation coefficient r=−0.69, P<0.001). [ABSTRACT FROM AUTHOR]