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Indicator Assessment
WORLD
The increase in global and European mean temperature, observed over the last decades, is unusual in terms of both magnitude and rate of change.
The global (land and ocean) average temperature increase up to 2006 was 0.76 °C compared to pre-industrial. Eleven of the last 12 years (1995 -2006) rank among the 12 warmest years in the instrumental record (since 1850), and 2005 and 1998 were the warmest two years than any year on record.
The rate of global average temperature change has increased from 0.08°C per decade over last 100 years, to 0.13 °C per decade in last 50 years and 0.23°C in last decade.
The best estimates for projected global warming from 1990 to the end of this century range from 1.8 to 4.0°C (likely range 1.1 to 6.4°C) for different scenarios which do not assume that more action is taken to limit emissions.
EUROPE
Europe has warmed more than the global average. The increase for the European land area and European land & ocean area has been 1.16°C and 0.95°C, respectively, comparing the trend towards 2006 with pre-industrial times. The warmest year in European land has been 2000, closely followed by 2006 and 2002.
The temperature changes has been largest in South-Western, central and north-eastern Europe and in mountainous regions.
In the past 100 years, cold days, cold nights and frost have became less frequent, while extreme high temperature as hot days, hot nights, and heat waves have became more frequent.
The annual average temperature for Europe is projected to rise this century 1-5.5°C (best estimate) with the greatest warming over eastern Europe and Scandinavia in winter, and over south-western and Mediterranean Europe in summer.
For Europe as whole it is very likely that hot extremes, heat waves, and heavy precipitation events will continue to become more frequent and cold events less frequent.
European annual average temperature deviations, 1850-2007, relative to the 1850-1899 average (in oC).The lines refer to 10-year moving average, the bars to the annual 'land only' European average.
Changes in duration of warm spells in summer across Europe, in the period 1976-2006 (in days per decade)
Occurrence of heat wave events with a duration of 7 days (left: 1961-1990 average; right: 2071-2100 average)
Note: Occurrence of heat wave events with a duration of 7 days (left: 1961-1990 average; right: 2071-2100 average)
Indicator elaboration: R. Hiederer, European Commission DG Joint Research Centre, Institute for Environment and Sustainability, 2007. Data: PRUDENCE Project 12km HIRHAM4, Danish Climate Centre, 2006.
The average temperature has increased 1.17oC and 0.93oC for the European land area and European land & ocean area*, respectively, comparing the trend towards 2006 with pre-industrial times** (CRU, 2006) (Fig. 3). As such Europe has warmed more than the global average (i.e. 0.95oC and 0.76oC for land and land & ocean). The warmest year in European land has been 2000 (1.18oC higher than pre-industrial), closely followed by 2006 and 2002. The warming is greatest over in South-Western, central and north-eastern Europe and in mountainous regions. Seasonal, temperatures are increasing more in winter than summer (Jones & Moberg, 2003; Fig. 4).
The annual average temperature for Europe is projected to increase 1- 5.5oC (comparing 2080-2100 with 1961-1990 average), taking into account the uncertainties in two future socio-economic development (IPCC-SRES A2 & B2 scenarios) and in climate models (IPCC, 2007b; Christensen & Christensen, 2007). The warming is projected to be greatest over eastern Europe and Scandinavia in winter (December to February), and over south-western and Mediterranean Europe in summer (June to August) (Giorgi et al., 2004; Christensen & Christensen, 2007). Especially South-Western Europe may experience a considerable warming in summer, exceeding 6oC in parts of France and the Iberian Peninsula (IPCC, 2007a,b).
Cold days, cold nights and frost have become less frequent in Europe (Fig. 7), while hot days, hot nights, and heat waves have become more frequent (Fig. 5) (IPCC 2007b). Especially the number of warm extremes has increased twice as fast over the last 25 years. It is more likely than not that anthropogenic forcing has caused this increase.
Along with the overall warming, heat waves and droughts across Europe are projected to increase in frequency, intensity and duration (Schär et al., 2004, Tebaldi et al., 2006, IPCC, 2007a,b; Beniston et al., 2007) (Fig. 6). Likewise, the night time temperature is projected to considerably increase, possibly leading to additional health problems (Halsnćs et al, 2007). Conversely, along with the projected increase for yearly minimum temperature for most of Europe, also winter temperature variability and the number of cold and frost extremes is very likely to further decrease (defined as lowest temperature occurring 1-in-10 years during 1961-1990) (Tebaldi et al., 2006, Beniston et al., 2007) (Fig. 7). Geographically, Central Europe could experience the same number of hot days by 2100 as currently observed in southern Europe and that Mediterranean droughts would start earlier in the year and last longer (Beniston et al., 2007). European regions projected to be most affected are the Iberian Peninsula, central Europe including the Alps, the eastern Adriatic seaboard, and southern Greece (Beniston et al, 2007; Kjellström et al., 2007).
* For the purpose of this indicator, Europe is defined as the land between 35o to 70o Northern latitude, -25o to 30o Eastern longitude, plus Turkey (=35o to 40o North, 30o to 45o East).
** For the purpose of this indicator, pre-industrial is defined as the period 1850-1899 (beginning of instrumental temperature records). At that time the anthropogenic influence was small compared to natural variation, temperatures in the late 19th century are in good agreement (order of 0.1o C) with conditions before the onset of industrialization in 1750.
Global annual average temperature deviations, 1850-2007, compared with the 1850-1899 average. The lines refer to 10-year moving average, the bars to the annual 'land and ocean' global average.
The Earth has experienced considerable temperature increases in the last 100 years, especially in the most recent decades. These changes are unusual in terms of both magnitude and rate of change. The temperature increase up to 2006 was about 0.76oC (land & ocean) compared to pre-industrial (defined as 1850-1899 average), about 1/3 of the EU 'sustainable' target of limiting global average warming to not more than 2oC above pre-industrial levels (Fig. 1). The 1990s were the warmest decade on record, eleven of the last 12 years (1995 -2006) rank among the 12 warmest years in the instrumental record (since 1850), and 2005 and 1998 were the warmest two years than any other year on record (Jones and Moberg, 2003, CRU, 2006; GISS/NASA, 2006). Note that 1998 experienced a strong El Nino, a warm water event in the eastern Pacific Ocean that adds warmth to global temperatures. In 2005 was about equally warm as 1998 without an El Nino event.
The rate of change in the global average temperature is accelerating from 0.08oC per decade over the last 100 years, to 0.13oC per decade over the past 50 years up to 0.23oC per decade over the last 10 years (all values represent land & ocean area) (IPCC, 2007a) (Fig. 2). As such the indicative target of 0.2oC per decade has been exceeded in the recent years.
The global average temperature is projected to increase 1.8 to 4.0oC (likely range 1.1-6.4oC) (from 1990) for the six IPCC SRES scenarios, comparing the 2080-2100 average with the 1980-1999 average. The range is caused by the uncertainties in future socio-economic development and in climate models. Note that these projections do not assume more policy action taken to limit greenhouse gas emissions (IPCC 2007a). Furthermore, these projections, based on the recent IPCC Fourth Assessment Report, are more advanced -as they provide best estimates and an assessed likelihood range for each of the marker scenarios- and now rely on a larger number of climate models of increasing complexity and realism, as well as new information regarding the nature of feedbacks from the carbon cycle and constraints on climate response from observations.
This indicator shows absolute changes and rates of change in average near-surface temperature for the globe and for a region covering Europe. Near-surface air temperature gives one of the clearest and most consistent signals of global and regional climate change, especially in recent decades. It has been measured for many decades or even centuries at some locations and a dense network of stations across the globe, and especially in Europe, provide regular monitoring of temperature, using standardised measurements, quality control and homogeneity procedures.
This indicator provides guidance for the following policy-relevant questions:
Global average annual temperature deviations, ‘anomalies’, are discussed relative to a ‘pre-industrial’ period between 1850 and 1899 (beginning of instrumental temperature records). During this time, anthropogenic greenhouse gases from the industrial revolution (between 1750 and 1850) are considered to have a relatively small influence on climate compared to natural influences. However it should be noted that owing to earlier changes in the climate due to internal and forced natural variability there was not one single pre-industrial climate and it is not clear that there is a rigorous scientific definition of the term ‘pre-industrial climate’.
Temperature changes also influence other aspects of the climate system which can impact on human activities, including sea level, intensity and frequency of floods and droughts, biota and food productivity and infectious diseases. In addition to the global average target, seasonal variations and spatial distributions of temperature change are important, for example to understand the risks that current climate poses to human and natural systems and to assess how these may be impacted by future climate change.
Units are degrees Celsius (°C) and degrees Celsius per decade (°C/decade).
Baseline period
Global average annual temperature is expressed here relative to a ‘pre-industrial’ baseline period of 1850 to 1899, and this period coincides with the beginning of widespread instrumental temperature records. During this time anthropogenic GHGs (greenhouse gases) from industrial activity before 1850 had a relatively small influence on climate compared to natural influences. However, it should be noted that there is no rigorous scientific definition of the term ‘pre-industrial climate’ because climate also changed prior to 1850 due to internal and forced natural variability. Other studies sometimes use a different climatological baseline period, such as the 1971-2000 period used in parts of the IPCC Working Group One contribution to the Fifth Assessment Report (IPCC, 2013).
This indicator provides guidance for the following policy-relevant questions:
The absolute change and rate of change in global average temperature are both important indicators of the severity of global climate change. Temperature changes also influence other components of the climate system which can impact on human activities, including the hydrosphere with oceans and the cryosphere.
To avoid serious climate change impacts, the European Council proposed in its Sixth Environmental Action Programme (6EAP), reaffirmed by the Environment Council and the European Council of 22-23 March 2005 (Presidency Conclusions, section IV (46)) and later in the Seventh Environmental Action Programme (7EAP, 2014) , that the global average temperature increase should be limited to not more than 2 0 C above pre-industrial levels. Furthermore the UNFCCC 15th conference of the parties (COP15) recognised in the Copenhagen Accord (UNFCCC, 2009) the scientific evidence for the need to keep global average temperature increase below 2 0C above pre-industrial levels. In addition, some studies have proposed a 'sustainable' target of limiting the rate of anthropogenic warming to 0.1 to 0.2 0 C per decade.
The target for absolute temperature change (i.e. 2 0C) was initially derived from the variation of global mean temperature during the Holocene, which is the period since the last ice age during which human civilization has developed. Further studies (IPCC, 2007;Vautard, 2014) have pointed out that even a global temperature change of below the 2 0C target would still result in considerable impacts. Vulnerable regions across the world, in particular in developing countries (including least developed countries, small developing island states and Africa), would be most strongly affected. The UNFCCC Copenhagen Accord (2009) therefore foresees a review in 2015 of the scientific evidence for revising the global temperature target to 1.5°C.
Mainstreaming climate change adaptation in EU policies is one of the pillars of the EU Adaptation strategy. In the Europe 2020 strategy for smart, sustainable and inclusive growth, the following is stated on combating climate change: “We must also strengthen our economies, its resilience to climate risks, and our capacity for disaster prevention and response”.
Various data sets on trends in global and European temperature have been used for this indicator:
Global and European average time series for monthly temperature
In the original source the long-term annual and monthly mean HadCRU global temperatures were calculated from 4349 stations for the entire period of the record. There is an irregular distribution in the time and space of available stations (i.e .denser coverage over the more populated parts of the world and increased coverage after 1950). Maps/tables giving the density of coverage through time are given for land regions by Jones (2003). The gridding method was climate anomaly method (CAM), which means the station temperature data have been converted to the anomalies according to the WMO standards (baseline period 1961-1990 and at least 15 years of station data in the period) and grid-box values have been produced by simple averaging of the individual station anomaly values within each grid box.
GISS surface temperatures were calculated using around 7200 stations from Global Historical Climatology Network, United States Historical Climatology Network (USHCN) data, and SCAR (Scientific Committee on Antarctic Research) data from Antarctic stations. Additionally satellite SST has been included for the period after 1980. Temperatures were transformed into anomalies using station normalisation based on the 1951 to 1980 baseline period. Gridding has been done with reference station method using 1200 km influence circle (Hansen et al. 2006).
Surface temperature mean anomalies from Global Historical Climatology Network-Monthly (GHCN-M) has been produced at the NCDC from 2,592 gridded data points based on a 5° by 5° grids for the entire globe. The gridded anomalies were produced from GHCN-M bias corrected data. Gridded data for every month from January 1880 to the most recent month is available. The data are temperature anomalies in degrees Celsius (Jones, 2003).
Other global climate datasets are used by the climate research community, often with a specific purpose or audience in mind, for example processed satellite Earth-observations, and climate reanalyses. Although these are not specifically constructed for climate indicator monitoring, they do show the same temperature trends described here. Recently one new global temperature dataset has been developed especially for understanding temperature trends. This is the Berkeley Earth temperature record: http://berkeleyearth.org/
Daily climate information
Although Europe has a long history in collecting climate information, datasets containing daily climate information across the continent are scarce. Furthermore, accurate climate analysis requires long term time series without artificial breaks. The objective of the ECA project was to compile such a data set, consisting of homogeneous, long-term daily climate information. To ensure a uniform analysis method and data handling, data were centrally collected from about 200 meteorological stations in most countries of Europe and parts of the Middle East. Furthermore the data were processed and analysed at one institute (i.e. KNMI) (Klok et.al. , 2008).
In order to ensure the quality of the ECA&D climate data set:
Global and European average time series for monthly temperature
Grid values of HadCRUT, GISTEMP and GHCN data sets have been gridded using different interpolation techniques. Each grid-box value for the HadCRUT dataset is the mean of all available station anomaly values, except that station outliers in excess of five standard deviations are omitted (Brohan et al., 2005). GISTEMP temperature anomaly data are gridded into 8000 grid cells using reference station interpolation method with 1200 km influence circle (Hansen et al. 2006). GHCN monthly data consists of 2,592 gridded data points produced on a 5° by 5° basis for the entire globe (Jones, 2003).
No methodology references available.
The observed increase in average air temperature, particularly during recent decades, is one of the clearest signals of global climate change.
Temperature has been measured over the centuries. There is a range of different methodologies which give similar results suggesting that uncertainty is relatively low. Three data sets have been presented here for the global temperature indicator. Global temperatures from HadCRUT, GISTEMP, and GHCN have been homogenized to minimise the effects of changing measurement methodologies and location.
Each observation station follows international standards for taking observations set out by WMO. Each National Meteorological Service provides reports on how its data are collected and processed to ensure consistency. This includes recording information about the local environment around the observation station and any changes to that environment. This is important for ensuring the required data accuracy and performing homogeneity tests and adjustments. There are additional uncertainties because temperatures over large areas of the Earth are not observed as a matter of routine. These elements are taken into account by factoring the uncertainty into global average temperature calculations, thereby producing a temperature range rather than one uniquely definite figure (WMO, 2013). The uncertainty of temperature data has decreased over recent decades due to wider use of agreed methodologies and denser monitoring networks. Uncertainty of the temperature data comes from sampling error, temperature bias effect and from the effect of the limited observation coverage. Annual values of global and European temperature are approximately accurate to +/- 0.05 degrees C (two standard errors) for the period since 1951. They are about four times as uncertain during the 1850s, with the accuracy improving gradually between 1860 and 1950 except for temporary deteriorations during data-sparse, wartime intervals. Estimating accuracy is difficult as the individual grid-boxes are not independent of each other and the accuracy of each grid-box time series varies through time (although the variance adjustment has reduced this influence to a large extent). The issue is discussed extensively by Jones et al. (2003), Brohan et al. (2005), and Hansen et al. (2006).
According to the IPCC 4th Assessment Report (IPCC, 2007), there is very high confidence that the net effect of human activities since 1750 has been one of warming. Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations. Moreover, it is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period (IPCC, 2013).
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/global-and-european-temperature/global-and-european-temperature-assessment-1 or scan the QR code.
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