Global Warming Effect on Comfort climate Conditions in Iran

Transcription

1 Advances in Environmental Biology, 5(11): , 2011 ISSN This is a refereed journal and all articles are professionally screened and reviewed ORIGINAL ARTICLE Global Warming Effect on Comfort climate Conditions in Iran 1 Dr. Reza Borna, 2 Dr. Gholamreza Roshan, 3 Dr. Alireza Khaje Shahkoohi 1 Department of Geography, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran. 2,3 Department of Geography, Golestan University, Gorgan, Iran. Dr. Reza Borna, Dr. Gholamreza Roshan, Dr. Alireza Khaje Shahkoohi: Global Warming Effect on Comfort climate Conditions in Iran. ABSTRACT Increase of temperature in the future decades may change humans' thermal comfort condition. In fact, global warming and increment of temperature in different regions will change indexes of thermal comfort and humans' health in these regions. This research aims at studying effects of global warming on thermal comfort conditions in Iran. To study the amount of temperature increment MAGICC SCENGEN compound model has been used together with four scenarios. Besides, to estimate thermal comfort in Iran adaptation model of ASHRAE institute called T c index has been used. In this study, Iran was divided into 30 zones and the present thermal comfort conditions were studied using meteorological data of 80 climatological stations and then changes of thermal comfort in 2025's, 2050's, 2075's and 2100's were studied. Findings of this study show that temperature of the 30 zones of Iran will increase by 2100's that based on all the scenarios this increase will be 4.5 degrees. This rise in temperature will be followed with a change in thermal comfort conditions. In all the decades and in all the 30 studied zones T c index will get increased and this increment will be higher and more intense in central and desert zones of Iran. The less increase of T c will be related to coastal zones of Caspian Sea and Oman Sea in southeast of Iran. Key words: Global Warming, Thermal Comfort, Energy, Iran. Introduction Human life has evolved within a temperature, humidity and solar radiation environment that has not varied much over thousands of years; we and the flora and fauna with which we share our plane, have limited capacity to adapt to rapid or extreme climatic changes [2,10]. Consumption of fossil fuel by humans has increased dispersion of Carbon dioxide and other greenhouse gases. All scenarios of International Panel of Climate Change (IPCC) and General Circulation Models (GCM) forecast that the rise in concentration of greenhouse gases may increase the global temperature [14]. Besides, new climatic models forecast that if the level of carbon dioxide continues to increase, then the average temperature of the earth will increase during the present century for about 1/4 to 5/8 Centigrade degrees [11]. Climatic changes and global warming resulted from increase of greenhouse gases may have harmful effects on human life. From among the probable effects of global warming are drought, destructive floods and increase of frequency and intensity of hurricanes, the increase in cold/warmth waves in different parts of the world which imperils humans' health. Based on reports of the World Health Organization (WHO), number of those dead due to climatic changes will reaches to persons in many parts of the world (which is 3% of the total number of the dead) [12]. Rise in temperature in the coming decades may change the humans' thermal comfort conditions. In fact, global warming and increment of temperature in different regions will change indexes of thermal comfort and humans' health in these regions. Interaction and mutual effect of temperature, average radiation temperature, rate of airflow and air humidity constitute human thermal environment [13]. The American Engineering Society of Heating and Cooling considers thermal comfort as mental conditions which indicate satisfaction with environmental heat [7]. When environmental temperature is normal and lets human body maintain its thermal balance without perspiration or trembling, human feels relief. Increase of humidity on skin surface may disturb human comfort [8,14]. In the formation of human comfort conditions in climate view, four elements of temperature, humidity, wind and radiation are important. Among these elements, temperature and humidity have more effects on health and comfort of human and for this Corresponding Author Dr. Reza Borna, Department of Geography, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran. bornareza@yahoo.com

2 purpose, most human comfort measurement models have been deployed on these two factors [1,9,16]. Considering the great effect of climate on human comfort, the man has ever seeking optimal usage of his surrounding climate and many scholars such as [6,3,4] and [15]. Since air temperature is one of the main factors in humans' climatic comfort, this study seeks to evaluate the effects of temperature changes on thermal comfort in the future decades in Iran. Materials and Methods The present research has been conducted with the purpose of studying effects of global warming on outdoor thermal comfort conditions in Iran. For this purpose, according to global warming models, thermal comfort conditions of Iran have been studied for he present five decades, 2025's, 2050's, 2075's and 2100's. To study bioclimatic conditions of the recent decade the data of climatological stations located at the thirty zones of Iran for a 25-year period (1981 to 2005) have been used and in for the purpose of forecasting and modeling temperature change due to increase of greenhouse gases at the present study MAGICC SCENGEN compound model has been used. MAGICC is a Model for Assessment of Greenhouse-Gas Induced Climate Change consisting 3512 of a set of interrelated simple models. This model uses some parameters as input in modeling process the most important of which is climatic sensitivity. SCENGEN is a regional and global Scenario Generator. This model is not only a climatic model but a simple database including results of many GCMs as well as a set of global perceptional data and four sets of regional climate data [14]. In calculations done in regard to Iran GFDLCM20 has been used together with 5 scenarios and change of temperature parameter has been estimated based on these scenarios. The scenarios used in this study are IPCC suggested scenarios. This model has degree dissociation ability. According to the fact that is located between 25 to 40 degree latitude and 44 to 63.5 degree east longitude and according to the aforesaid division power, Iran could be divided into 30 geographical zones, the temperature changes of each of which has been modeled. It is necessary to mention that the provinces located in west and northwest line of the country are not included in the zone with 2.5 degree division power. Figure (1) shows the geographical situation and boundaries of the 30 zones. Results of this model for temperature in 2025's, 2050's, 2075's were analyzed. Fig. 1: Division of the 30 Zones of Iran based on MAGICC SCENGEN model. In order to study thermal comfort conditions in Iran, comfort temperature adapted index presented by ASHRAE institute has been used. This model can be calculated a follow [10]: In this equation, T c is thermal comfort index and T o is temperature outdoor. Here, index area for Iran is introduced as follow (Table 1): Tc = / T o

3 3513 Table 1: Level and Division of Comfort Temperature based on the suggested method (T c). Tc Comfort Area 22>Tc Lack of comfort due to coldness 23>Tc>22 Almost cold 27>Tc>23 Comfort 29>Tc>27 Almost hot Tc>29 Lack of comfort due to heat To analyze the results of this index, the outcomes of this index were compared to results of the two temperature-heat indexes (THI) and Backer index using experimental and objective data related to years 1970 to This process was done for the thirty zones and finally the correlations extracted from this index were presented in table 3. Temperature-heat index is calculated as follow: THI = 0.72 (Td + T w ) In this index, THI is temperature-heat index, Td is temperature dry and T w is temperature wet. In this index values more than 80 and lower than 60 show lack of comfort. Bicker method is also calculated as follow: C p = ( V ) ( t) mcal/cm/sec In the above equation, C p is cooling power of environment based on microcalorie/cm/sec; V is average wind speed based on m/sec; t is daily temperature based on Celsius degree. C p values in Bicker method is between 0 and 59. According to the fact that there is a good and acceptable correlation between results of the three methods, in this research the method suggested by ASHRAE institute (T c ) has been used. Table 2 shows the correlation between results of ASHRAE method, THI and Bicker methods. Results and Discussions Iran's Temperature Changes: In order to study temperature changes in the thirty zones of Iran, data of 80 climatological stations have been selected to show the present temperature of Iran and comparing it to temperature changes of the country in the future decades. Besides, 5 scenarios suggested by IPCC have been used for studying temperature changes in Iran in the future decades which are: BIAIM, AIASF, BIASF, AIMES. Based on the used scenarios we will have a rise in temperature in all the thirty zones of Iran in the future decades, that of course this temperature rise is higher and more intense in some regions and less in others. Based on the achieved results, the maximum temperature rise is related to AIASF scenario. According to all the used scenarios, the maximum increase of temperature is related to zones 12 (East Esfahan), 13 (East Yazd), 18 (West Yazd, North and Northwest Kerman), 19 (Northeast Kerman, South southern Khorasan) and 20 (North Sistan Baluchestan). In general, in the future decades most zones of Iran will experience a considerable temperature rise. The least rise in temperature in the coming decades is related to zones 1 (West Caspian Sea, West Gilan), 2 (Northwest Golestan) and 3 (Golestan). Regarding the effect of greenhouse-gases increase and due to results of scenarios, the most increase of temperature is related to internal and low parts of Iran. At present, these parts have arid climate. These regions are far from humidity resources. As we get far from central regions of Iran and get close to south and north coastal areas of Iran the rate of temperature rise in coming decades decreases. In fact, regions close to coast and south and north latitudes of Iran will experience a less increase off temperature in the future in comparison to central and internal parts of Iran. In general, the average rise of temperature in the 30 zones of Iran by 2100's will be 4.6 Centigrade degree based on AIMES scenario, 4.3 Centigrade degree based on BIASF scenario, 5.6 Centigrade degree based on AIASF scenario and 3.4 Centigrade degree based on BIAIM scenario. Average temperature in the 30 zones of Iran is about 19.9 Centigrade degree at present. Figure (2) shows average of temperature changes across Iran based on results of different scenarios by 2100's. Changes in Thermal Comfort Conditions: Thermal comfort conditions in Iran have been studied based on the method suggested by ASHRAE institute. In fact, thermal comfort conditions of the thirty zones of Iran have been studied annually. Taking into consideration the increasing trend of temperature in the thirty zones of Iran, thermal comfort conditions will experience some changes under influence of this temperature rise in the future decades. Based on results of all scenarios all across Iran the increase of T c from the present time till 2050's will be considerable and intense. Based on results achieved from AIMES scenario the amount of T c in all thirty zones of Iran will have an average increase of 1.2 times by 2100's. Based on the same scenario, the maximum increase of T c is related to central Iran and desert regions of Iran. In fact, these regions are known as zones 18, 19, 20 which include northwest Kerman, east Yazd, south of southern Khorasan and north Sistan Baluchestan. Table (2) shows T c changes based on AIMES scenario in the thirty zones of Iran.

4 Abcd 3514 Fig. 2: Temperature changes in Iran by 2100's. Table 2: T c Changes from the Present Time till 2100's based on AIMES Scenario. Region Present(2000) 2025 s 2050 s 2075 s 2100 s Based on BIASF scenario, T c value will experience some changes all across Iran from the present time till 2100's. Based on this scenario, the maximum increase in T c value will be related to zones 13, 14, 18, 19 and 20 which in fact include internal and arid regions of Iran. The amount of increase in T c value will be about 1.3. Based on the same scenario, the least increase of T c is related to coastal regions of Caspian sea and regions close to coast of Oman sea in southeast of Iran. Level of increase in these regions will be about 0.9 by 2100's. Based on BIASF scenario, just like the previous scenario, the maximum increase of T c is related to internal parts of Iran.

5 3515 Table 3: T c Changes across Iran based on BIASF Scenario. Region present 2025 s 2050 s 2075 s 2100 s From among the used scenarios, AIASF scenario shows the highest increase in T c value for Iran. Based on results of this scenario, the increase amount of T c in Iran from now till 2100's will be about 1.5. Results of this scenario show that from among the thirty zones of Iran, zones 13, 18, 19 and 20 will experience the most increase of T c by 2100's. Zone 13 includes Yazd province. Increase of T c in this zone will be about 1.8 which indicates the maximum increase from among the thirty zones. The minimum increase of Tc is related to southeast part of Iran which includes zones 29 and 30. These zones include south Sistan Baluchestan and southeast Sistan Baluchestan (Table4). Table 4: T c Changes in Iran based on AIASF Scenario. Region present 2025 s 2050 s 2075 s 2100 s

6 AIAIM scenario shows the least increase of T c for Iran by 2100's. Based on results of this scenario T c value will have an increase of 0.8 by 2100's. Results of this scenario show that the maximum increase of T c is related to zones 12, 19 and 20. In these regions, an increase of about 1 in T c will be experienced by 2100's. Based on the same scenario, the least increase of T c is related to coastal zones of Caspian Sea which include zones 1 and 2 and southeast parts of Iran which include zone 29 and 30 (Table 5). In general and based on average of all scenarios, the amount of increase in T c by 2100's will be about 1.2 in Iran. Table 5: T c Changes in Iran based on AIAIM Scenario. regions present 2025 s 2050 s 2075 s 2100 s Conclusion: The present research has been conducted aiming at studying thermal comfort conditions in Iran in the future decades under effect of global warming. Results of this study show that based on the used model and defined scenario, we will have a rise in temperature in Iran by 2100's. This increase of temperature will be more intense and higher in central parts of Iran. Zones 12, 13, 18, 19 and 20 will experience the highest temperature rise by 2100's. In general and based on average of all the scenarios, the value of temperature increase across Iran will be 4.5 degree by 2100's. According to the expected rise of temperature indifferent parts of Iran, some changes will also occur in thermal comfort conditions. In this study, the method proposed by ASHRAE institute (T c method) has been used to study thermal comfort conditions. Based on all scenarios, Iran will experience a rise in T c in the future decades. During these changes, most parts of Iran will suffer from unfavorable conditions in regard to thermal comfort and some cold and mountainous regions of Iran such as zone 16 will enjoy a better thermal comfort condition. From among the thirty zones of Iran, the highest increase of T c is related to zones 13, 18, 19 and 20 which include internal and low lands of Iran which have hot and desert climate at present. During the coming decades, the minimum increase of T c will be related to zones 1, 2, 29 and 30. Zones 1 and 2 include coastal zones of Caspian Sea and zones 29 and 30 include costal parts of Oman Sea in southeast of Iran. References 1. Alijani, B., A new approach to yhe application of water and meteorology in resources management and development of country, the role of climate in housing design. Geographical. Research. Seasonal, 4:

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