2014 warmest year on record in Europe
Climate Indicator Bulletins (CIBs) are user-driven climate information products which provide simple, effective and timely knowledge abstractions from the large amount of observation and reanalyses data available in EURO4M. The bulletins focus on user groups in sectors such as disaster prevention, health, energy, water resources, ecosystems, forestry, agriculture, transport, tourism and biodiversity at European, national and local levels.
This bulletin presents an overview of the European temperature for 2014, based on a large number of measurements. Recent observations are placed in a historical context and special attention is given climate impact indices.
Last update: 19 January 2015.
Warm annual mean temperature
2014 is the hottest year on record in Europe. The analysis of observations indicate that the annual (January to December) mean temperature for Europe has reached 11.22˚C which is nearly 0.17˚C above the previous record set in 2007. The top-10 of warmest years has all its entries from the past 15 years, with 1989 the only exception, at fifth place.
Figure 1: Graph of Jan-Dec temperatures averaged over Europe, with respect to the 1981-2010 climatology. Temperatures below normal are in blue, temperatures above normal are in red, with the 2014 value in green.
Surface air temperatures are measured at an extensive network of stations in Europe. These data are collected and aggregated into European temperatures. The annual mean values in this E-OBS dataset are presented above for the land area between between 35˚-75˚N and 25˚W-45˚E (top panel, red and blue bars). The green bar represents data for the year 2014. The warmest years in Europe cluster at the end of the series with 2014 being the warmest year on record.
The grey bars in all three panels indicate the estimated uncertainties which take into account the errors introduced by spatial interpolation over areas without observation stations, inhomogeneities in the temperature data that result from station relocations / changes in measurement instruments etc., and biases due to urbanisation, as documented in Van der Schrier et al., 2013 and Chrysanthou et al., 2014. The uncertainties tell us that although we are not 100% certain about the ranking of individual years, the overall positive trend since the 1980s is very pronounced and 2014 sticks out, even when taking the uncertainties into account.
A map of the annual mean temperature (Jan 1st-Nov 30st) with respect to 1981-2010 climatology shows that all of Europe was warmer in 2014 than average temperatures, with pronounced increases from Central to eastern Europe and Scandinavia. Southern European countries show lower anomalies but still positive, with the exception of parts of the Iberian Peninsula where lower than average temperatures were observed.
Nineteen European countries have seen their hottest year on record, including Austria, Belgium, Croatia, Czech Republic, Denmark, France, Germany, Hungary, Iceland, Italy, Luxembourg, The Netherlands, Norway, Poland, Serbia, Slovakia, Slovenia, Sweden and the United Kingdom.
Warm seasonal temperature anomalies
The seasonal temperature anomalies (with respect to the 1981-2010 climatology) show the warm winter, spring and autumn observed in Europe. Winter (Dec. 2013 - Feb. 2014), the third warmest since 1950, was very warm over most of Europe. The Iberian Peninsula, Ireland and Turkey had more modest warming. The anomalously high temperature continued into Spring (March, April, May 2014) with the strongest warming over Eastern Europe. Averaged over Europe, Spring 2014 ranks as the warmest since 1950. Summer 2014 was near normal or even colder in Central and South Europe, although it still ranks as the eleventh-warmest summer since 1950. Eastern Europe and especially Scandinavia have seen warmer than usual conditions. Autumn (Sep., Oct., Nov.) 2014 was again anomalously warm over most of Europe and ranks as sixth since 1950.
Figure 3: Map of anomalous seasonal temperatures with respect to the 1981-2010 climatology. Winter values relate to the 2013/2014 December-January-February season.
Warm days and warm nights in 2014
The figures below show the increase or decrease in the percentages of warm day-times and warm nights for 2014, with respect to the climatology (1981-2010). A warm day-times or nights is defined as a day where the maximum (TX) or minimum (TN) temperature exceeds the climatological 90th percentile. This threshold is calculated for each position on the map, making it specifically suitable for local conditions. In 2014, Scandinavia and parts of central Europe show similar percentages of warm day-times and nights.
For France and most of Germany, the percentage of warm day-times outnumbers the percentage warm nights. This is the opposite for the UK, Denmark, the Iberian Peninsula, Italy and the Balkans where there are a lot more warm nights than warm day-times. The high frequency of warm nights is relevant from the health perspective; high night-time temperatures have adverse effects on human health.
However, the number of very warm (tropical) nights where the minimum temperature exceeds 20°C, did not increase over large areas (see the Climate Impact Indices at CII 2014).
Figure 4: Map of the number of warm days (left) and warm nights (right), with respect to the 1981-2010 climatology. The warm days and nights are based on the daily maximum and minimum temperatures respectively.
The mean sunshine duration of Jan-Nov 2014 and the summer anomaly with respect to the 1961-1990 climatology is presented in the maps below. With high amounts of sunshine in summer, the summer anomaly dominates the Jan-Nov anomaly. Much of Europe has seen above average sunshine amounts, with Greenland and parts of Northeastern Europe (mainly Finland, Poland and Russia) standing out in this respect. An area from France, over Northern Italy into the Balkan Peninsula to Turkey shows below average sunshine amounts.
Figure 5: Maps of the sunshine duration accumulated over the January-November 2014 period (left) and the anomalous sunshine duration maps for summer, with respect to the 1961-199 climatology.
Summer days index is defined as the number of days in a given period where TX > 25°C. The anomaly of 2014 shows Central Europe with near-average anomalies. North Italy and the Balkans show below average anomalies which is in line with the somewhat disappointing summer temperatures in these areas given in previous figures. Southern Spain and Portugal present a different behaviour than the rest of the Mediterranean with above average amount of summer days. Scandinavia and eastern Europe experienced above average summer days with eastern Europe having the highest increase in the region.
Figure 6: Map of the number of summer days (daily maximum temperature > 25°C) with respect to the 1981-2010 climatology.
Annual maximum one (RX1day) and five day (RX5day) precipitation indices show large amounts of above-normal precipitation in a band from northern Italy to southern Balkan countries and south Turkey. The floods in Serbia and Bosnia and Herzegovina, which occurred in mid-May 2014, relate to these excessive precipitation intensities in 2014. The same pattern is shown by other climate indices in CII 2014, like annual number of wet days, the total spring precipitation and the number of extremely wet days.
Central and eastern Europe experienced below average amounts, both for the annual maximum 1 and 5 day accumulated precipitation. Above average precipitation amounts were presented in the southwest part of the Scandinavia peninsula, while the northern part experienced below average conditions.
Figure 7: Maps of the number of the annual maximum 1-day (left) and 5-day (right) precipitation amounts with respect to the 1981-2010 climatology.
This is in line with the longer dry periods observed in northern Scandinavia, Romania and the Ukrain, the inland of Spain and over the Czech Republic, see the additional material in the Climate Impact Indices page CII 2014
Climate indices for 2014
A selection of indices is presented here. A full review of the climate impact indices derived for 2014 can be found here CII 2014
The role of global warming: Attribution
Global warming significantly contributed to the high 2014 temperatures, according to new research from three independent climate science teams from the UK, the Netherlands, and Australia.
To assess the potential link between Europe's record-breaking hottest year and global warming, Climate Central coordinated an effort with scientists from the Royal Netherlands Meteorological Institute (KNMI), the University of Oxford, the University of Melbourne and the Australia National University looking into this. The three teams conducted independent assessments, using different approaches involving statistical analyses of the historical temperature record from a combination of E-OBS and the Climatic Research Unit and the results of thousands of simulations with state-of-the-art climate models.
Below is the statement from their press release.
"In the early 1900s, before global warming played a significant role in our climate, the chances of getting a year as warm as 2014 were less than 1-in-10,000. In fact, the number is so low that we could not compute it with confidence," Geert Jan van Oldenborgh, a climate scientist at KNMI, said. The analysis by van Oldenborgh concluded that global warming has made a temperature anomaly like the one observed in 2014 in Europe at least 80 times more likely. For many individual countries the probability has increased by at least a factor of 30 (e.g., the UK, many countries in Central Europe).
Using a large computing network (weather@home), Oxford scientists simulated possible European weather based on the observed global ocean temperatures. At the same time, they also simulated a 2014 where there is no human-influenced climate change. Comparing those two “worlds” they found that the 2014 European temperatures were much more likely in the world with climate change than the one without.
“It is important to highlight that Oxford’s result crucially depends on the 2014 global ocean temperatures. The same study using 2000-2011 conditions gives a different result although the anthropogenic warming is the roughly same in these years,” said Fredi Otto, a climate scientist at the University of Oxford. “When looking at smaller regions in Europe, we notice that there is a higher variability of temperatures,” Karsten Haustein, a colleague of Otto who conducted the analysis, said. “For example, in central Europe we found that the probability of reaching the observed 2014 temperatures is about 40 times higher. In an even smaller region such as the UK, we found that the probability has increased by a factor of about 10.”
The analysis from climate scientists at the University of Melbourne and the Australian National University showed similar results. Their approach utilized the Coupled Model Intercomparison Project phase 5 (CMIP5) experiments. "By comparing climate model simulations representing the world as it is with simulations of a world without humans, we show that the risk of warm years like 2014 occurring has very likely increased by at least 35-fold,” said Andrew King, a climate scientist from the University of Melbourne who conducted the analysis. “This means that human-induced climate change has very likely played a significant role in 2014 being a record hot year for Europe."
Authors: Christiana Photiadou, Gerard van der Schrier, Geert Jan van Oldenborgh, Gé Verver, Albert Klein Tank, Maarten Plieger (KNMI, The Netherlands), Hermann Mänchel, Peter Bissoli, Stefan Rössner (Deutscher Wetterdienst, Germany).
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