Search

The aim of the study is to present changes in air humidity in central Poland in the years 1966-2000 in Łódź as an example. The values of air temperature, relative humidity and atmospheric pressure from four observation terms, 00, 06, 12 and 18 UTC, were used. On this basis, the saturated vapour pressure, the current vapour pressure, and the saturation deficit were calculated. Then, the variability of these three indicators and relative humidity was examined. The variability of monthly and seasonal average values of humidity indices in four observation periods was presented, the trends in seasonal variability of humidity indices were calculated and the distribution functions of their distributions were compared in the midday period in three 15-year periods: 1966-1980, 1986-2000 and 2006-2020. It has been shown that the pressure of saturated water vapour is the highest in summer, the lowest in winter, and slightly higher in spring than in autumn at all times, except for the night. It increased significantly in the studied period as a result of the increase in air temperature. A comparison of the distributions in three 15-year periods shows a significant increase in the probability of occurrence of high values of saturation vapour pressure, even above 30hPa. The water vapour pressure in the air is highest in summer and lowest in winter, but in spring it is lower than in autumn. All trend coefficients are positive, but only less than half are statistically significant. A comparison of the distributions over three 15-year periods show a slight increase in the probability of higher values of the actual vapour pressure. The saturation deficit, as the difference between the previous two indicators, increases significantly. Its value in spring is significantly higher than in autumn. The trend is positive, especially in spring and summer, and the comparison of distributions shows that in the last 15 years the probability of high values of saturation deficit increased significantly. The course of relative humidity is the opposite of saturation deficit. In autumn, the relative humidity is definitely higher than in spring. The trend is down. To sum up, warming brings an increase in the capacity of the atmosphere for water vapour, a slight increase in the amount of water vapour in the air, but also a significant increase in saturation deficit and a decrease in relative humidity, which is particularly strong in spring in the first half of the growing season. [ABSTRACT FROM AUTHOR]

Ekstrema ciepła to dni z wyjątkowo wysoką temperaturą powietrza w danym miejscu i/lub porze roku. Często wiążą się one z negatywnymi konsekwencjami dla zdrowia i życia człowieka, a także środowiska przyrodniczego, rolnictwa i gospodarki. Globalnemu ociepleniu klimatu towarzyszy wzrost częstości ekstremów ciepła, co przyczynia się do intensywnego rozwoju badań na ich temat. W tym opracowaniu podjęto próbę podsumowania stanu wiedzy na temat ekstremów ciepła w Europie, ze szczególnym uwzględnieniem metod ich identyfikacji, rozpoznania ich przyczyn i następstw oraz oceny ich zmienności wieloletniej i trendów. Zestawienie wyboru prac na temat tych złożonych zdarzeń może pomóc w zidentyfikowaniu zagadnień, które wciąż wymagają zgłębienia i wyjaśnienia, tym samym stanowiąc wstęp do dalszych rozważań. Hot or warm extremes are days with exceptionally high air temperatures in a given place and/or season. They may have significant impacts on human health and life, the natural environment, and the economy. The global rise in near-surface air temperatures translates into increases in the frequency, intensity, and duration of such events, which contributes to the intensive development of research on them. This review aims to summarize the state of knowledge of hot and warm extremes in Europe, with a special focus on their definitions, physical drivers and impacts, long-term variability and trends. The study demonstrates that research on temperature extremes is making remarkable progress, but there are still issues to be explored to understand these complex events. [ABSTRACT FROM AUTHOR]

The study discusses changes in the average annual air temperature over Europe in the years 1931-2020. The results of the research show that in 1987-1989, there was a sudden change in the thermal regime over Europe and a discontinuity appeared in the course of this climatic element. In the years 1931-1988, despite the high inter-annual variability, the temperature trend was zero. A positive, statistically significant, temperature trend appeared after 1988. The entire warming in Europe, which can be estimated at ~2.3 deg, occurred after 1988. The discontinuity in the course was caused by an abrupt change in macro-circulation conditions in the Atlantic-Eurasian circulation sector, which manifests itself as a fundamental change in the frequency of the macrotypes of the mid-tropospheric circulation (500 hPa) according to the Wangengejm-Girs classification, causing an equally fundamental change in the weather structure. The change in macro-circulation conditions was forced by a change in the thermal state of the North Atlantic - a sharp increase in the intensity of oceanic heat transport to the north. The analysis showed that the annual variability of temperature over Europe was mainly influenced by natural processes, the variability of which explains ~65% of its variance. Radiative forcing, which is a function of anthropogenic increase in CO2 concentration in the atmosphere, explains only 7-8% of the variability of the average annual temperature over Europe, being a secondary or tertiary factor in shaping its changes. [ABSTRACT FROM AUTHOR]

Ongoing changes in climate (increases in air temperature, changes in the distribution of precipitation over the year) exert an influence on the genesis of watercourse supply, as expressed in relation to the three sources represented by rain, snowmelt and groundwater. In that context, to the work detailed here had as its aim the spatial and temporal determination of the structure (and trends) characterising winter hydrological half-year runoff from selected river catchments in the Western Carpathians, in the assumed circumstances of a changing climate and growing anthropopressure. To ensure adequate characterisation of the situation, the study took in four drainage basins, representing both the Beskid Mountains as such (in the catchments of the Soła and Osława), as well as their Foothills (in the catchments of the Skawinka and Stobnica). It was in relation to these four watercourses that the nature of the supply was determined over the 40-year (1981-2020) period, in regard to mean daily flows in the profiles closing the selected catchments. Interpretation of the nature of supply was made possible by meteorological data concerning precipitation totals and types, thickness of snow cover and air temperature. Mean values for winter half-year precipitation totals (PWHY) ranged from 226.5 mm (Skawinka) to 440.6 mm (Soła). The share of annual total precipitation (PA) accounted for by PWHY ranged on average from 30.1% (Skawinka) to 43.9% (Soła). The average winter half-year totals for snowfall (SF) in the study period ranged from 104.8 mm (Skawinka) to 313.4 mm (Soła). It was thus in the latter two catchments that the extreme shares of overall precipitation in the winter hydrological half-year accounted for by snowfall were to be found, at 30.9% and 43.7% respectively. Average values for runoff in the winter half-year (HWHY) ranged from 150.3 mm (in the Skawinka catchment) to 348.8 mm (in the Osława catchment), while the share of annual outflow (HA) accounted for by HWHY averaged between 50.9% (Soła) and 60.4% (Stobnica). The 1981-2020 period was not found to be characterised by any statistically significant directions of change in HWHY, though negative HWHY trends could be noted for all the catchments studied in regard to the years since 2000, with the range of relevant values being 4-7 mm·year-1. The 4 catchments showed a diversity of dominant sources of supply in HWHY. In the case of the Soła, it was supply by snowmelt that took the largest (40.1%) share, while in the Osława supply by rainfall prevailed (at 38.0%), and in the Skawinka supply by groundwater (on 43.4%). The catchment of the Stobnica featured more or less equal shares of alimentation by precipitation and ground supply (at around 36-38% in each case). All 4 catchments manifested declines over time in snowmelt-induced runoff, albeit with these ranging from 0.3 mm·yr-1 (Skawinka) to 1.2 mm·yr-1 (Soła), while the role of supply involving groundwater is seen to be on the increase by between 0.17 mm·yr-1 (Skawinka) and 1.04 mm·yr-1 (Osława). In addition, the trend for increase in ground supply was found to be several times more distinct in the catchments of the Beskids as such, compared with their foothills, with marked spatial differentiation being the feature. In the catchments present in the foothills, the increase in ground supply proved similar, regardless of location. Changes in land cover can be regarded as affecting the magnitudes of values for the a runoff coefficient for the WHY. Average values were lower in the foothills catchments: Stobnica (64%) and Skawinka (67%). In the catchments located in the Beskids per se, the average a values proved to be higher, with differences between catchments also greater (Soła on 72% and Osława on 94%). The negligible change over the study period when it came to the Skawinka catchment could be related to a 5-fold increase in built-up areas, even as the most-major reduction in the runoff coefficient noted in the catchment of the Stobnica, was attributable to a reduction in the share of arable land from 61.0% (in 1990) to 46.4% (in 2018), with a concomitant increase in forest cover from 32.1 to 43.4%. Study of the a runoff coefficient attributable to rain revealed regional variations. While a downward trend characterised the eastern part of the research area (i.e. the Stobnica and Osława catchments), the trend was upward in the western part (where the Soła is located). It was notable how a downward trend for values of the a runoff coefficient either arose or intensified in all catchments across the 1999-2020 sub-period. Furthermore, the whole 40-year study period did witness a downward trend for values of the coefficient for runoff attributable to snowfall in all 4 catchments, with this intensifying further in the 1999-2020 sub-period (hence in the same way as with the coefficient for rain-related runoff). The research results presented here attest to progressive increases in air temperature affecting precipitation types and totals, and thus also activity as regards the different forms of watercourse supply in water. To this extent the working hypothesis established gained confirmation empirically, with demonstrably declining magnitudes and shares of river runoff accounted for by the thawing of snow and ice. [ABSTRACT FROM AUTHOR]

The phenomenon of mass death of mussels in the Rusałka reservoir in Poznań took place in July 2018. As a result of this incident, the Unionidae population has been depleted. The number of dead mussels was counted, which floated around the banks and in the water. A total of approximately 5,500 deaths were found. Due to the scale of the phenomenon, the analysis of water quality was carried out by the Voivodeship Inspectorate for Environmental Protection in Poznań. Four samples of water were taken from different depths of the reservoir to perform physico-chemical and biological analyses. Two profiles, oxygen and temperature, were made in the deepest place of the Rusałka reservoir. There was a presence of hydrogen sulphide at the 5-meter depth of the reservoir. Additionally, oxygen concentration decreased strongly with depth to total deoxidation (< 0.50 mg·l-1O2 from 5 meters depth to the bottom). Furthermore, the average air temperatures in May 2018, in Poznań, were more than 3°C higher than in 2017 and 2016. In June and July, temperatures increased on average by 1 and 2°C compared to the previous. It was shown that the mass death of mussels was probably the result of the interaction of high temperature, a lack of oxygen, and the presence of hydrogen sulphide. It is not possible to clearly indicate only one factor that led to this phenomenon. [ABSTRACT FROM AUTHOR]

This study was designed to explore the impact of meteorological factors (air temperature, relative and absolute humidity, wind, cloudiness and precipitation) on influenza morbidity in four selected big cities in Poland - Cracow, Poznań, Warsaw and Wrocław. Atmospheric data obtained from four meteorological stations spread over six years (2013-2018) were compared to influenza-like illnesses (ILI) reports, obtained from the Voivodship Units of the State Sanitary Inspection for the same locations and period. Data were analysed using Spearman correlation and negative binomial regressions to capture the nonlinear relationship between exposure to environmental conditions and influenza morbidity. Our study found a strong negative association of absolute air humidity with influenza infections (RR = 0.738) and positive relationship with minimal temperature (RR = 1.148). The effect of wind speed, cloudiness and precipitation on ILI was less evident. Proposed model is valid for all age groups in Polish cities, but suits the best to elderly citizens (65+). The model is also appropriate for different seasons, however only absolute humidity, minimal temperature and wind speed are considered significant variables all year round. Furthermore, we observed 6 to 9-days delay between particular adverse weather conditions and ILI morbidity increase, as 1-week lag model proved to have the highest predictive power (AIC = 8644.97). Although meteorological variables have statistically significant contribution to explain influenza morbidity, there are also other non-climatic factors, that can possibly influence the seasonality and complexity of influenza epidemiology in Polish cities. [ABSTRACT FROM AUTHOR]

While significant increases in air temperature are being observed in the context of climate change, precipitation characteristics, indicators and indices seem to be changing in a more regionally-variable manner. High-mountain areas prove particularly subject to fluctuations and changes of climate, given that mountains serve as barriers to masses of air flowing over them, with the result that atmospheric precipitation totals are high in the context of the so-called orographic rainfall. Overall, the Chornohora represents the highest range anywhere in Ukraine's Carpathian Mountains, as there are six peaks over 2000 m a.s.l. capable of serving as a barrier running NW-SE. Nevertheless, the main ridge of the High Tatras (of the Slovakia-Poland borderland) is even higher and runs W-E. Each massif is some 30 km in length, while the two ranges are separated by a distance of almost 350 km. Main drainage divides run along the highest ridges here, with the Tatras separating the drainage basins of the Vistula and Danube, while the Chornohora represent a divide between the Prut and Tysa basins. However, the later destination of the latter's waters are in both cases the Danube. [ABSTRACT FROM AUTHOR]

This article seeks to analyse the universal thermal climate index (UTCI, °C), in order to characterise hazards associated with high air temperature that may possibly occur in Poland around noon on very hot days. Values for the index (calculated for UTC by reference to air temperature (°C), relative humidity (%), wind speed (v·ms-1) and cloudiness (%)) related to from the Polish cities of Kołobrzeg, Poznań and Kraków, and to the period 2001-2018. Mean values with standard deviations were calculated, with minimum and maximum values noted, amplitudes, lower and upper quartiles and the skewness coefficient. One-way analysis of variance was deployed to determine whether UTCI values at midday on very hot days differ significantly from month to month. The frequency of occurrence of different intensities of heat stress was also determined. In each case, analysis related to both the overall period and individual years. Hours around noon on very hot days were mainly associated with "moderate" or "severe" heat stress, though instances "very sever heat stress" may also arise. The greatest threat of thermal heat stress could be noted for July and August, with conditions noticeably more severe in Kraków than the other stations studied. Kołobrzeg faced the most- -limited hazard associated with the occurrence of heat stress, and only in July may "very severe heat stress" appear there sporadically. In turn, Poznań - located in a region with bioclimatic conditions typical for Poland - was rather characterised by "moderate" or "severe heat stress". [ABSTRACT FROM AUTHOR]

Thermal regime has a critical impact on the lotic environment, as maximum temperature determines the boundaries of the occurrence of aquatic species, seasonal and diurnal water temperature variations affect their bioenergetics, while the timing of specific water temperature values during the year is important in the context of spawning and migrations. However, despite the great importance of water temperature studies in the context of environmental management and fisheries, as well as the development of accurate measurement techniques, such investigations have received relatively limited attention in Poland. The current study attempted to examine the seasonal differentiation of water temperature in lowland rivers. For this purpose, water temperature was recorded from the 1st of May 2015 to the 30th of April 2019 with a temporal resolution of 30-minutes. Digital temperature reorders used to make the measurements were distributed across six sites in Jeziorka, Świder and Utrata catchments located on the Mazovian Lowland and the Southern Podlachia Lowland near Warsaw. The hydrometeorological background of the water temperature monitoring was determined on the basis of data from the Warszawa- -Okęcie station and water gauging stations. On the basis of the measurement data, mean, maximum, and minimum monthly water temperatures were calculated and presented on the background of the appropriate air temperature data, while statistical distribution of the 30-minute water temperature, aggregated in a monthly timescale, was presented on the box and whiskers plots. The Ward method was used to group months similar in terms of their thermal conditions, while the Pearson correlation coefficient was applied to evaluate the strength of the relationship between water and air temperature. The results indicate that the seasonal course of water temperature follows the course of air temperature, with the highest mean monthly water temperatures recorded in July, while the lowest in January. Statistical distribution analysis of water temperature in individual months and its grouping by the Ward method allowed to identify two periods characterized by relatively stable thermal conditions and two periods of dynamic changes of water temperature. In contrast to the maximum values of water temperature, which were observed in the summer as a result of intensive solar radiation and low streamflow rates, the greatest variability of water temperature, as indicated by reference to mean daily range and standard deviation, was found in the spring months, i.e. in April and May, while the lowest in winter, from December to February. The relationship between daily mean water temperature and air temperature, established with the use of the Pearson correlation coefficient on a monthly basis, was clearly stronger during the spring increase and the autumn fall of the water temperature, which can be linked with greater vulnerability to atmospheric heat fluxes. A definitely weaker relationship was found in the winter and summer months, when greater importance can be attached to other drivers of stream temperature, like the presence of ice cover, cloudiness, riparian shading, and groundwater inflows. [ABSTRACT FROM AUTHOR]

One of the classifications of atmospheric circulation types applied in Poland is the typology proposed by Lityński (1969). Circulation types were designated based on three classes in each of three indices (zonal Ws, meridional Wp, and cyclonicity index Cp). Indices Ws and Wp were developed based on differences in atmospheric pressure over the area of 40°-65°N and 0°-35vE. A total of 27 types were designated. Calendars of the types in reference to the period 1951-1999 were published. Lack of information on particular stages of development of the calendars seems to preclude unequivocal interpretation in their use. It is not clear what reference period was considered in the development of the calendars. An example is provided that a change in the reference period causes the shift of 5% of days to another class. The name of the type does not always concern the direction of air advection. For example, in January, the middle class „0" zonal index is characterised by air advection from the west. In such a situation, the type called „S" in practice describes inflow of air from direction „SW". An example is also provided of a situation where the same value of the Wp index was qualified in June to class „S", and in November to class „N". Examples of analyses are also presented with the application of daily values of Wp and Ws concerning air temperature, snow cover, and UTCI index. Attention is drawn to the need of high degree of caution in the interpretation of research concerning multi-annual periods where results of reanalyses were used as source data. It is pointed out that the annual courses of circulation indices Wp and Ws may be approximated when the determination of air density considered the same temperature in reference to all days in a year. [ABSTRACT FROM AUTHOR]

The study presents the spatial and temporal variability of warm and cold days occurring in the years 1966-2017 at five meteorological stations representing four peripheral areas and the centre of Poland. The analysis was based on the daily maximum air temperature values. A warm or cold day was considered as a day during which the maximum temperature was respectively higher or lower than the average daily temperature by a value of 1.28 standard deviation for a given calendar day. The obtained results indicate an increase in the frequency of the occurrence of warm days sequences and a decrease in the number of sequences of cold days, especially after 1990. The analysis also found a clear differentiation of the annual course of the considered days depending on the geographical location of the area in question. The most distinctive is the north-western region of Poland, where the highest number of warm days was recorded. In contrast, the area of southern Poland is characterized by a higher number of cold days. Most of the analyzed days occurred as one- or two-day long sequences, constituting approximately 70-80% of all cases. In the analyzed period, short (lasting 3-5 days) waves of warm or cold days were most frequent, and the longest waves (lasting at least 11 days) usually accounted for less than 1% of all cases recorded at a given station. [ABSTRACT FROM AUTHOR]

The quality of a given bioclimate is much affected by the atmospheric environment (taken to include solar radiation, air temperature and humidity, atmospheric pressure, wind speed and levels of atmospheric pollution), as well as by geographical factors relating to topography and cover, the drainage system and land use (Owczarek 2009, Czarnecka, Nidzgorska-Lencewicz 2010, Koźmiński, Michalska 2011, Owczarek 2012). Tourists staying in a coastal area must contend with considerable variability of weather from one day to another, or even hour by hour, in the cold half-year in particular. Changes of weather have a profound effect on the human organism, inter alia giving rise to migraines, sleep disturbances and hypersensitivity. The work described here sought to assess temporal (inter alia seasonal) and spatial variability to heat loading of the human organism characterising the Polish Baltic coastal zone, as well as the temperature of water by beaches. It was to achieve this kind of assessments of bioclimate and its impact on the human organism that the index known as the UTCI (Universal Thermal Climate Index) was devised, taking in air temperature, wind speed, air humidity and absorbed solar radiation (expressed as mean radiant temperature) (Ba¿ejczyk & Kunert, 2011). This index represents objective changes in physiological parameters of the human organism occurring thanks to differing environmental conditions as determined in relation to a 10-point scale for heat loading of the human organism (°C) that translate into descriptive terms ranging from extreme heat stress to extreme cold stress. UTCI values referred to here were calculated using BioKlima 2.6 software - http:// www.igipz.pan.pl/Bioklima-zgik.html. Six zones for the heat loading of the human organism found to be present along the Polish coast during the four seasons of the year were designated by summing the frequency of occurrence of days with a particularly stimulating effect, be this severe or very severe heat stress or severe, very severe or extreme cold stress. The UTCI-based analysis sustained conclusions as follows: The Polish Baltic coast is found to be characterised by marked day-to-day variability in the heat loading of the human organism, particularly in the November-late May period, with the result being a significant "nuisance" represented for tourists. Along the western part of the coast and in the area of the Bay of Puck, conditions thermoneutral for the human organism were found to dominate (accounting for more than 60% of the days in a month) over the whole period from May through to mid-October. In the case of the northern part of the coast from Darłowo to Łeba the same was found to be true of the period extending from June through to the middle ten-day period of September, creating conditions favourable for outdoor recreation. The duration of the bathing season with mean monthly water temperatures =18°C is of approximately 45 days along the coast from Darłowo to Łeba, 46-50 days in the central part of the coast, 46-60 days in the area of the Bay of Gdańsk and 61-70 in the area of the Bay of Pomerania. In most years under analysis, there was no identification of a bathing season with mean monthly water temperature =18°C in the Kołobrzeg and Władysławowo areas. The bioclimatic conditions most favourable for recreation and tourism were identified for the area of the Bay of Pomerania, followed by the Bay of Gdańsk. Less- -favourable conditions characterise the central part of the coast, while the least favourable circumstances extend through the northern area from Darłowo to Łeba, in which the bioclimate's stimulatory effect is strongest. The high spatial variability characterising heat loading of the human organism that it proved possible to identify for the Polish coast offers the possibility of particular regions and seasons being selected for recreation, in relation to tourists' health status and specific requirements. [ABSTRACT FROM AUTHOR]

The aim of the study was to estimate the rate and extent of overgrowth of a water reservoir on the example of Lake Gardno, based on the normalized index of vegetation NDVI. In the assessment of the changes taking place in individual summer seasons within the lake basin a thorough analysis was made based on satellite imagery performed for the years 2000-2014. The main assumption was to develop an appropriate method to determine the extent of expansion of water vegetation on the example of the selected lake. Preliminary results were compiled with monthly average air temperatures and monthly mean precipitation totals, then a detailed analysis was performed to demonstrate the relationships between the effective overgrowth and local meteorological conditions. The observed changes in the ever- -growing litoral zone allowed us to suppose that Lake Gardno is going to disappear. [ABSTRACT FROM AUTHOR]

The study determines the frequency of monthly thermal anomalies in the Mediterranean Basin (approx. south of 45oN), in the area from Lisbon in the west to Van in eastern Turkey, changes in the frequency of such anomalies over six decades, as well as the location and size of the area over which they occurred. The present study is based on the average monthly air temperature values from 80 meteorological stations in the years 1951-2010. Thermally anomalous months are considered to have occurred when the average air temperature t at a given station differed from the corresponding tav. by at least 2 standard deviations (s); for anomalously cold months (ACMs: t£tav.-2s) and for anomalously warm months (AWMs: t=tav.+2s). One feature that distinguishes the Mediterranean Basin from the rest of Europe located in the temperate climate zone is the prevalence of AWMs over ACMs. The number of ACMs and AWMs showed significant variations over the 60-year period. The years 1971-1980 were the coldest ones, while the 21st century saw the highest temperatures. The vast majority of ACMs and AWMs occur over small areas. There were 22 anomalous months (11 ACMs and AWMs) that covered larger areas (at least 25% of the stations). [ABSTRACT FROM AUTHOR]

The paper identifies trends in the change in extreme air temperature characteristics, including the average, maximum and minimum temperatures, at 22 Polish weather stations during the period 1951–2006. The statistical analysis included the determination of ≤ 10 and ≥ 90 percentile temperatures, the number of extremely cold days (Tmin≤ –30°C), extremely hot days (Tmax ≥ 35°C) and hot nights (Tmin ≥ 20°C). It was found that the trends in the air temperature were not only related to changes in thermal conditions observed across Central Europe, but were often synchronised. In the long-term, there was a gradual increase in the temperatures, as was the number of extremely hot days, while the number of extremely cold days was falling. Around the year 2000, there were seasons and entire years that reached very high temperatures to the point, in some cases, of extreme values. Indeed, this was a period with the highest air temperatures since the beginning of instrument–based records. It also involved an increase in the number of extremely hot days and a decrease in the number of extremely cold days thus confirming trends observed earlier in these two types of days in Poland. A comparison of the long-term change in the maximum and minimum air temperatures reveals that their average annual values are always statistically significant, which suggests a warming of the region's climate. The picture changes, however, when looking at seasonal and monthly values, both average and exceptionally high or low; and the change becomes less clear and mostly statistically insignificant over a large proportion of the country. This is confirmed by the results of long-term studies into the variability of extreme thermal conditions in the southeastern Polish region of Małopolska in the second half of the 20th century (Bielec-Bąkowska and Łupikasza 2007). This may mean that the intensity of the climate warming observed is not high enough to be translated into a visible change in extreme conditions. The sources of variability of the thermal conditions in Poland also remain debatable. Natural factors, prominently featuring atmospheric circulation, seem highly influential, but are also strengthened by antropopressure, including the urban heat island. This latter proposition is confirmed by the fact that the temperature increase observed greatly exceeds the natural climatic variability (IPCC 2007). [ABSTRACT FROM AUTHOR]