Concept

Global Warming

Industrial Revolution in the early 19th century and the human social and economic development have changed people’s lifestyle significantly. The need for energy and consumption of fossil fuels like coal, oil and natural gas have resulted in increased emission of carbon dioxide and other greenhouse gases into the atmosphere. These emissions have changed the energy balance of the earth and its atmosphere. Global population growth has caused land use change, deforestation, increased agricultural and livestock activities, and increased solid and liquid waste production, resulting in many environmental problems including climate change.

Atmospheric models predict that the earth temperature will increase from 1 to 3.5º C by the year 2100, which is more than temperature changes during the past 10,000 years.

Emission of greenhouse gases, production of aerosols in the atmosphere, changes in the earth’s reflection index, and thermal pollution are the factors affecting climate change. Among these factors, the effect of greenhouse gases is well known and is the most important one.

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Fig. 1 Temperature changes from 1860 to 1980.

Greenhouse effect

The earth absorbs most of solar radiations that reach the earth through its atmosphere and, after getting warm, reflects the thermal waves back to space. Portion of this infrared radiation passes through the atmosphere and a fraction of it is absorbed by greenhouse gases and reflected back to the earth surface which results in an energy balance between the earth and space (Fig. 2).

Fig.2- Energy balance between Earth and space.

This so called greenhouse effect is a natural phenomenon, which has created the normal temperatures ranges in the atmosphere. Indeed, if the greenhouse effect did not exist, the earth’s average temperature would have been about 15.5 degrees lower than the temperature that it has now and another ice age would occur. However, the concentration of greenhouse gases in the atmosphere have exceeded the normal level by as much as 30%, resulting in global warming.

Fig.3- Direct contribution of greenhouse gases to global warming.

Greenhouse gases

Water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), troposphere ozone (O3), chlorofluorocarbons (CFCs), hydro-fluorocarbons (HFCs), and perfluorocarbons (PFCs) are known as greenhouse gases. All of these gases are responsible for greenhouse effect, but water vapor and CO2 have 90% contribution to this effect.

Greenhouse gases are emitted both from “ natural sources” and “anthropogenic sources”. They are also absorbed by “sinks” which are mainly forests and oceans. Some greenhouse gases such as ozone are produced in the atmosphere by photochemical reactions.

Lifetime in the atmosphere is an important characteristic of the greenhouse gases and different greenhouse gases have different lifetime, thus different greenhouse effect. CO2 is the key greenhouse gas responsible for global warming and the potential of other gases is compared to this gas. Table.1 shows greenhouse emission sources and sinks and their lifetime in the atmosphere.

Table.1 Natural and anthropogenic greenhouse gases and their lifetime in the atmosphere

What are the impacts of Global Warming?

Changes in temperature and precipitation patterns, which depend on latitude, attitude, and ocean streams in different areas, affect the climate of the earth. Some of the impacts of climate change are:

• Sea level rise,
• Disruption of water resources,
• Regional climate change in northern hemisphere and upper latitudes,
• Changes in precipitation pattern and wind,
• More severe weather conditions (storms, floods, etc.),
• Increased frequency and severity of drought and drier deserts, and adverse health effects (diseases such as Malaria and Yellow Fever).

National Circumstances of Iran

The Islamic Republice of Iran lies in western Asia. In the north it is littoral to the Caspian Sea and borders Azerbaijan, and Turkmenistan. It is contiguous with Turkey and Iraq to the west. In the south the country is littoral to the Persian Gulf and the Sea of Oman and abuts Pakistan and Afghanistan to the east. The principal and official language is Farsi (Persian). The population in 1994 (the base year) was about 57.7 million (now estimated at 72.0 million). The area coverage of different types of climate in Iran is 35.5% hyper-arid, 29.2% arid, 20.1% semi-arid, 5% Mediterranean, and 10% wet (of the cold mountainous type). Thus more than 82% of Iran’s territory is located in the arid and semi-arid zone of the world.
The average rainfall in Iran is about 250 mm, which is less than 1/3 of the average rainfall in the world (860 mm). In addition, this sparse precipitation is also unfavorable with respect to time and location. Another important climatic element is extreme temperature changes that sometimes range from –20^oC to +50^oC.
Severe drought is also recognized as a feature of Iran’s climate. In the last three years, the country has suffered severe desiccation and this lack of rainfall has resulted in extensive losses.

Climate Change Impacts on Iran

Based on the research and assessment carried out during the Climate Change Enabling Activity Project under UNFCCC, and using the scenarios proposed by IPCC, it is estimated that if the CO2 concentration doubles by the year 2100, the average temperature in Iran will increases by 1.5 - 4.5ºC which will cause significant changes in water resources, energy demand, agricultural products, and coastal zones.

The “direct” adverse impacts of climate change include changes in precipitation and temperature patterns, water resources, sea level rise and coastal zone, agriculture and food production, forestry, drought frequency and intensity, and human health. The “indirect” adverse economic impacts result from the response measures taken by the developed countries.

Assessment of Direct Adverse Impacts of Climate Change

• Temperature and Precipitation

  To provide an insight into what will happen if the GHGs emissions issue is not properly managed, six scenarios have been designed. These scenarios were selective combinations of two GCMs (HadCM2 and ECHAM4) models, three emission scenarios, and three different climate sensitivities. Low emission combination resulted in an increase in temperature ranging from 1° to 1.5° C. Changes for the second combination range from 2.5° to 4.1° C and the third combination resulted in an increase in temperature ranging from 5.9° to 7.7° C. The same patterns were used to portray precipitation variations in the country. The resulting fluctuations appear in the following ranges:
  

  - 11% to 19.1% of the baselines for low emission rate,

  - 30.9% to 50% of the baselines for medium emission rate, and

  - 58% to 80% of the baselines for high emission rate.

• Water Resources

  Research on the global warming effects on hydrology and water resources in Iran has been undertaken on several rivers and lake basins by using historical hydro-meteorological data and runoff models in combination with the global warming scenarios. The result of historical runoff data surveys collected at 398 hydrometric stations shows that the Flood Index has changed in 47% of them. In addition, of 600 climatological stations studied, 68 indicate climate changes during 1990-2000.

  The long-term runoff model applied to 30 basins shows that the temperature rise increases the runoff volume during winter and decreases it during spring as rising temperature melts snowfall into rain and hastens the time of snow melt. It also indicates that temperature increase affects runoff of basins and decreases the amount of runoff variation of rainfall.

• Agriculture

  The predicted increase in temperature due to global warming may lead to spikelet sterility in rice, loss of pollen viability in maize, reversal of vernalization in wheat and reduced formation of tuber bulking in the potato for the areas near the threshold. The changing climate will affect wheat, which is the main staple crop. The historical data indicates that as a result of drought and reduction of rainfall, wheat production will be sharply reduced. Losses inflicted by the 1998-1999 droughts on wheat production nationwide are estimated at about 1,050,000 tons of irrigated wheat and 2,543,000 tons of rain fed wheat. The figures indicate that agricultural areas are highly vulnerable to climate change.

• Forestry and Land Use

  Climate change has a profound impact on the forestry sector. This includes changing the habitat location of forest species, especially the less tolerant ones and the extinction of low tolerant species. The natural regeneration regime of forest plants is upset and results in the reduction of wood and non-wood production in forests. Forests witness pests and plant disease infestation and an intensification of land erosion, particularly in arid and semi-arid zones. Sea-based mangrove forests are degraded and sometimes destroyed because of the rise in sea level in the Persian Gulf and Sea of Oman.
  Environmental conditions for wildlife in forest areas decline sharply as does forage production in rangeland, which can in some cases signal the onset of desertification. Soil erosion is the natural result of destruction of plant cover and all such conditions are exacerbated by high temperature and aridity. One social consequence of this environmental downgrading is population migration because of ecological insufficiency.

• Coastal Zones

  The northern part of Iran is a center of agricultural production. The southern region is home to the energy industry and hence oil installations and energy exports. The nation’s largest ports for export of goods are also located in the south. These characteristics of both north and south define Iran as being vulnerable to climate change impact.
  According to the 10-year hourly-recorded data in three sites (Chabahar, Bandar Abbas and Bushehr), the mean sea level in the Persian Gulf and Sea of Oman has been rising at an average value of 4.5 mm/yr, which agrees with the IPCC 1995 scenario. The impact of temperature and sea level rise namely: coastal erosion in the north and south; inundation of low lands such as the Miankaleh peninsula and Gorgan Bay; mass bleaching of the coral reef, salt water intrusion caused by flooding and inundation are all outstanding instances of the vulnerability of Iran’s northern and southern coastal zones.
  From a socio-economic point of view, climate change has a great adverse impact on the availability of fresh water in these regions. Saltwater intrusion both into surface water and groundwater are the most important issues, particularly in the Karun River system, which is the main source of drinking water for the population centers of more than one million people and has been subject to salt water intrusion caused by sea level rise combined with a low river flow.

• Health

  Climate change will cause direct adverse health effects. Global warming is expected to lead to more cardiovascular, respiratory, and other diseases. In particular, one of the major vector born tropical diseases is Malaria, which is prevalent in different provinces of Iran. The research on the exposure rate to Malaria from 1982 to 1998 indicates that the trend cases of those infected are on the rise.

• Energy and Industrial Processes

  Reduction in efficiency of thermal power plants, decrease in hydropower production resulting from lower water level in dams, destruction of coastal and offshore oil, gas and petrochemical installations in southern coastal zones caused by severe sea storms are the significant impact of climate change. It is estimated that global warming causes an increase in electricity demand of about 20,000 MW in the next 50 years.

GHGs Mitigation Assessment

Iran has high potential for alleviating the amount of GHGs emission. In the energy sector, the principal policies being pursued are clean and efficient power generation, environmentally friendly refineries, improved vehicle and public transport and energy-efficient buildings and appliances. Similarly, in the non-energy sector, reduction strategies include modern farm and livestock management, protection of forestlands and other natural resources, plus control and treatment of wastewater, disposal management and recycling of solid wastes.