Climate change Spain
Air temperature changes until now
Spain's rugged terrain and geographic location produce substantial climate variability. Differences in annual average temperatures of over 18 ºC are recorded at separate sites on the mainland. Temperature trend analysis confirms that there has been a widespread rise in annual average temperature since the mid-1970s, with warming being more apparent in winter (1,9).
Average temperature in the last 100 years has risen slightly more in Spain than the rest of the EU: 1 ºC compared with 0.9 ºC. This increase has been as much as 2 ºC in regions such as Murcia (8). Other data for temperature rise have also been reported: an average temperature rise in Spain in the previous century of 1.2-1.5 ⁰C, compared with an average temperature rise of 0,74 ⁰C globally and 1 ⁰C in Europe, in the same period (2).
In Spain temperature rise has been especially high in spring and summer (2,27). Since 1850 maximum and minimum temperatures in Spain have increased on average by 0,12 and 0,10 ⁰C/decade, respectively (2). There is a clear trend to fewer cool nights and more warm nights since 1960, and also to fewer cool days and more warm days (10).
Near the coast the frequency of frost days has decreased (−0.6 days/decade), especially from 1965 onwards. From 1980 onwards the frequency of summer tropical nights has increased in the southeast of Spain (+3.8 days/decade), and the frequency of summer days has increased in Southern Spain (+2.3 days/decade) (19).
In the whole Pyrenees region, an increase of mean surface air temperature of the mountain range of 0.21 °C per decade and a decrease in precipitation by 2.5 % per decade have been observed in the period 1950-2010 (33).
In the central Pyrenees minimum and maximum annual temperature have increased over the period 1910-2013 by 0.06 ⁰C per decade and 0.11 ⁰C per decade, respectively (31). This increase was larger over the period 1970-2013: 0.23 and 0.57 ⁰C per decade for minimum and maximum annual temperature, respectively. In this latter period spring is the season that presents the greatest warming, with 0.4 ⁰C per decade for minimum temperature and 0.9 ⁰C per decade for maximum temperature (31).
During the period 1901–2005, annual temperature of the northern part of the Iberian Peninsula has risen by about 0.13 °C per decade, with a 95% confidence interval lying between 0.09 and 0.16 °C per decade. This trend is much higher during 1973–2005, with a central estimate of the trend given by 0.51 °C per decade and a 95% confidence interval of 0.36–0.69 °C per decade (13).
Between 1959 and 2005 the occurrence of warm events in the winter (December to March) in the Ebro basin has increased (25). The annual number of warm days (defined as days with maximum temperature higher than the 90th percentile of all observations of maximum temperature during this period) increased from 3–8 days per winter at the beginning of this period to 14–22 at the end of this period. Also, there was a marked and statistically significant increase in the number of melt events at altitudes >2000m a.s.l. in the Pyrenees during recent decades. The increase was particularly evident in the number of melting nights (defined as nights with minimum temperature at 2000 m a.s.l. higher than 0 °C) (25).
Precipitation changes until now
Average annual precipitation ranges from barely 150 mm to over 2500 mm. Another feature is the high level of year-on-year climate variability and the significant differences in maximum and minimum daily values. Rainfall variability is so great that coefficients of over 20% are recorded in the Mediterranean regions and Canary Islands, while sequences of consecutive days without rain can last longer than 4 months in the southern half of the country (1).
From an analysis of data of a large number of meteorological stations in Spain and Portugal for the period 1951-2002 a general decrease in the daily intensity of rainfall has been observed, while the number of wet days does not reveal pronounced changes (4,12). Similar results were shown for the period 1950-2012 for Spain, most especially along the Mediterranean (37). This pattern is valid for both annual and seasonal values. The decreasing trend found for precipitation intensity in winter and annual series for some localities may be related to the predominance of the positive phase of the North Atlantic Oscillation (NAO). From this analysis it could not be concluded whether the detected trends are the result of global warming or of natural decadal variability.
Total precipitation (P) and precipitation intensity (I ) seem to have decreased for several northern and southern weather stations in winter, and for some southern stations in spring. Precipitation intensity seems to have decreased also in some southern stations in summer, and in some northern and southern stations in autumn (4). A reduction of precipitation in southern Spain of around 23% in the last 30 years has been reported (8). The reduction in the amount of annual rainfall in the Iberian Peninsula since 1960 is largest in the northwest and lowest reduction in the east (10). The Extremadura region (southwestern Spain) has become more arid in the period 1951-2010 (36).
The analysis on the behavior of rainfall in the eastern part of the country, in the Ebro Valley, or in the Spanish plateau, toward the central area of the country did not detect significant trends during the period 1951-2002. Results have also been reported, however, that show extreme daily rainfall decreases in the Mediterranean region as a result of the increase in the frequency and persistence of sub-tropical anticyclones (3).
During winter, the large-scale circulation is mainly driven by the position and intensity of the Icelandic low, and most of the Iberian Peninsula is affected by westerly winds that carry moist air and produce rainfall events. In the northern coast, rainfall is mostly due to meridional fluxes that, associated with the local orography, force an ascent of the air mass and, consequently, produce precipitation. In the Mediterranean coast, precipitation is mainly produced by easterly air flows. This region is sheltered from the intense Atlantic disturbances by the central Spanish plateau and the Pyrenees, and also by higher land flanking the Mediterranean coast(4).
The positive phase of the NAO, therefore, is related to a decrease in the number of wet days; meanwhile, the negative phase of the NAO would be related to an increase in the number of wet days all over the country, except in the north coast (4).
During 1970–2007 the thickness of the snowpack in the Pyrenees has decreased (21). The number of snow days in the Pyrenees has been decreasing over the period 1971–2000 (30).
Wind climate changes until now
An analysis of a 27 year long wave buoy dataset (1983-2010) recorded at Cadiz (SW Spain) did not show a clear trend in wave climate and storminess (20).
Glacier changes until now
Glaciers in eight of the nine European glacial regions are retreating. Pyrenean glacial retreat has been most notable (8). The Pyreneeshave lost almost 90% of their glacier ice in the previous century and the rest may disappear within a few decades. The melting rate of the ice that is still there keeps increasing: between 2002 and 2008 the Spanish Pyrenees lost about a quarter of their volume (5).
Sea temperature changes until now
Temperatures in the Catalan Sea have increased around 1.1°C in the uppermost waters (0 to 50m) and around 0.7°C at 80 m over the last 35 yr (from 1974 to 2008) (16), which is a similar rate to that inferred from satellite observations between 1985 and 2006 for the western Mediterranean (0.03°C per year (17)). The change in temperature in the northwestern Mediterranean Sea in the last decades seems to be more pronounced than the temperature increase in the oceans on a global scale. A recent compilation of temperature time series from the western Mediterranean Sea reveals a consistent warming pattern over the last 40 yr at a very similar increasing rate (18).
Air temperature changes in the 21st century
The EEA currently predicts a rise in average temperature in Spain of around 4 degrees by 2080 (which is confirmed by (10)). Extreme summers like the 2003 spell are likely to become four times as common in Spain and southern Europe. Under high emission scenarios every second summer in Europe will be as hot or even hotter than 2003 by the end of the twenty-first century. In southern Europe, these changes are projected to occur even earlier (in Spain by the 2020s). The report by the EEA puts the expected rise in temperature in Europe at between 2 and 6.3 degrees by 2100 (8).
Temperatures in Spain are forecast to rise steadily by 0.4ºC a decade in winter, and by 0,6-0.7ºC in summer. By 2100 temperatures in the hinterland of the Peninsula would be 5-7⁰C higher in summer and 3-4ºC in winter. Temperatures on the coast would rise by some 2ºC less than the hinterland. The number of days with extreme high temperatures would rise (6).
The projected temperature rise at the end of the 21st century differs by 3⁰C for low and high greenhouse gasses emissions scenarios. Generally, the rise in temperature is expected to accelerate at the end of the 21st century. Temperature rise is expected to be comparable for all regions in the winter, more in central and southern regions in spring, and more in the interior than along the coast in summer and autumn. Maximum temperatures are expected to rise more than average and minimum temperatures (2).
Climate projections indicate that the mean air temperature across the mountain range of this region will increase in the range of 1-2 °C by 2030 and 2.5-5 °C by 2100 compared with the current situation (34).
According to climate change projections for the Ebro basin for the periods 2021–2050 and 2051–2080, compared with 1961-1990, based on 12 regional climate models and the A1B emissions scenario, the number of warm winter nights (December to March) will continue to increase, especially in the mountain areas (25). In this study, warm nights were defined as nights with minimum temperature higher than the 90th percentile of all minimum temperatures calculated for the reference period 1961-1990.
Heat wave and cold spell changes in the 21st century
In Spain and Portugal the number of heat waves, their duration and intensity will increase in the course of this century. At the same time, less cold spells will occur, and they will become less intense. This was shown in a study where the impacts of a high-end scenario of climate change (the so-called RCP8.5 scenario) were assessed for two future periods, namely mid-term (2046 - 2065) and long-term (2081 - 2100), and compared with the recent-past reference climate (1986 - 2005) (32).
The definition of heat waves and cold spells
To what extent heat waves or cold waves may change not only depends on the scenario of climate change we choose or the time slice in the future, it also depends on the definition of a heat wave or a cold spell. Many different definitions are being used, that may lead to different conclusions. In this study (32), a heat wave is defined as the period of, at least, three consecutive days in which the maximum temperature during a day is equal or above a certain threshold temperature. Each day of the year has its own threshold that is calculated from a database over the period 1986-2005. The threshold for a certain day is the 10 % highest temperature in a period of 31 days centred around that day for a period of 20 years (the recent-past climate of 1986-2005). For example, the threshold for 1 July is the temperature that is exceeded on 10 % of all days during 15 June – 15 July over the 20-year period of 1986-2005.
Likewise, a cold spell is defined as the period of, at least, three consecutive days in which the minimum temperature during a day is equal or below a certain threshold temperature, where this threshold is defined as the 10 % lowest day temperatures during the 31 days around a certain day over the period 1986-2005.
This way, the daily climatological threshold series follows closely the seasonal cycle. What’s’ more, the threshold also varies with location in Spain and Portugal because the thresholds for heat waves and cold spells are calculated for a lot of locations across the Iberian Peninsula. This tailor-made definition allows for an assessment of regional differences in heat wave and cold spell changes.
Up to 40 times more heat wave days in Spain and Portugal
Both halfway and at the end of this century, the number of heat waves and heat wave days are expected to increase in all studied locations across Spain and Portugal. Relative to the reference for 1986-2005, the number of heat waves is projected to increase between 2 and 4 fold. The number of heat wave days is expected to increase even more, and reach between 4 and 40 times the value for 1986-2005. The latter is due to the fact that not only the number of heat waves but average heat wave duration is also expected to increase significantly at all locations. Besides, heat waves will become more intense (hotter) and especially night-time temperatures will increase strongly, making it hard for citizens to recover from the heat of the day. Projected changes are smallest in the north (near the cities of Gijón and Corunha) and highest in Barcelona. Under a high-end scenario of climate change, many future summer days at the end of this century will be heat wave days, particularly in Barcelona, Cáceres and Sevilha (32).
No more cold spells at the end of this century?
Very few cold spells were detectable in the results of this study for mid-term future, and none at the end of this century, except for Barcelona. The cold spells that still may occur, are of smaller duration and intensity than those of today (13).
For the Basque Country, model studies (based on 6 Regional Climate Models from the ENSEMBLES project (14), for the A1B emission scenario) showed a 50% decrease in the number of frost days (Tmin < 0°C) at the end of the century. Cold-wave episodes, defined as 6 consecutive days having temperatures lower than the seasonal temperature during 1978– 2000 by 5°C, are expected to disappear beyond 2020. The number of heat waves (6 consecutive days having temperatures higher than the seasonal temperature during 1978– 2000 by 5°C), is projected to increase from the current 12% of summer days to 16% in 2050 and 22% by the end of the century (14).
Precipitation changes in the 21st century
Generally, precipitation is projected to decrease all over Spain, and this decrease is expected to accelerate at the end of the 21st century. With respect to the present situation the annual precipitation is projected to decrease by 5% in the central, northern and eastern regions, and by 10% in the southwest in 2011-2040. In 2070-2100 the projected decrease is 15 (low emissions scenario) - 25% (high emissions scenario) in the central and northern regions, and 20 (low emissions scenario) - >30% (high emissions scenario) in the south (2) (see also (10)). Along with an increase in the duration of droughts an increase in the occurrence of heavy precipitation events is projected (23,24).
For specific regions and specific seasons, different estimates have been reported, however. For Andalucía and the upland parts of Cataluña climate model calculations suggest a significant annual precipitation reduction of between 6 to 14% at the end of the 21st century (compared with 1971-1990). In contrast, an increase is calculated in annual totals of up to 14% along parts of the coast between Almería and the French border (7). Projections suggest that in the already wet northeast rainfall might increase in winter (6).
In the Pyrenees the largest decline of accumulated annual precipitation is projected for summer (about 40 %) and largely unchanged precipitation patterns are projected for winter (35). The Pyrenees are likely to experience hotter, drier summers (8,22,23); a precipitation decrease up to 20% in 2050 (compared with 1971-2000) has been reported for summertime in the Pyrenees (22). Projections for wintertime differ, however: some project wetter winters (8), others a decrease of winter and autumn precipitation up to 30 % in 2050 (compared with 1971-2000) (22)). Snow cover on the mountains will probably be less in the future since, in most temperate mountain regions, the snow temperature is close to the melting point and therefore very sensitive to changes in temperature (8). The increase in air temperatures will especially affect snow cover in the Pyrenees in the zone between 1500 m a.s.l. and 2000 m a.s.l. (26). For northern Spain the annual number of snowfall days is projected to decrease by 2.0 days less /decade, according to climate model projections over the period 2011 – 2050 (A1B scenario) (29).
For the Iberian Peninsula there is no consensus on the changes in extreme precipitation for 2070–2100. Results of different climate models suggest that extreme precipitation over the Basque Country may be expected to increase by around 10% throughout the 21st century (15).
Climate change projections for the end of this century (2071–2100) (based on A2 scenario) show an increase in the mean length of dry spells and in the largest dry spells related to a 2-year return period (11). A lengthening of the dry season for Central Spain and Portugal has also been projected for the 2041 - 2070 period (compared to 1961 – 1990) for a high-end scenario of climate change (the so-called RCP 8.5 scenario) for a large number of global climate models (28).
Wind climate changes in the 21st century
According to model calculations no significant change in wind climate is projected for the 21st century (2).
The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Spain.
- Government of Spain. Quinta Comunicación Nacional de España
- Comisión de Coordinación de Políticas de Cambio Climático (2007)
- Lana et al. (2005), in: Rodrigo and Trigo (2007)
- Rodrigo and Trigo (2007)
- Ministerio de Medio Ambiente, y Medio Rural y Marino (2008)
- Christensen et al. (2007a), in: Chust et al. (2011)
- Sumner et al. (2003)
- European Environment Agency (EEA), JRC and WHO (2008)
- Brunet et al. (2009)
- UK Met Office et al. (2011)
- Sánchez et al. (2011)
- Rodrigo (2010)
- Brunet et al. (2007), in: Chust et al. (2011)
- Hewitt (2005), in: Chust et al. (2011)
- Chust et al. (2011)
- Calvo et al. (2011)
- Nykjaer (2009), in: Calvo et al. (2011)
- Vargas-Yáñez et al. (2010), in: Calvo et al. (2011)
- Fernández-Montes and Rodrigo (2012)
- Rangel-Buitrago and Anfuso (2013)
- Morán-Tejeda et al. (2013)
- Gonçalves et al. (2014)
- Barrera-Escoda et al. (2014)
- Rodríguez et al. (2014)
- López-Moreno et al. (2014)
- Szczypta et al. (2015)
- Gonzalez-Hidalgo et al. (2015)
- Guerreiro et al. (2016)
- Pons et al. (2016)
- Buisan et al. (2015), in: Pons et al. (2016)
- Pérez-Zanón et al. (2017)
- Cardoso Pereira et al. (2017)
- OPCC (2015), in: European Environment Agency (2017)
- European Environment Agency (2017)
- AEMET (2008); López-Moreno and Beniston (2009), both in: European Environment Agency (2017)
- Moral et al. (2017)
- Serrano-Notivoli et al. (2018)