GLOBAL CLIMATE AND MICROCLIMATE. Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan

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1 GLOBAL CLIMATE AND MICROCLIMATE

2 Perhaps the single most important influence on Earth s environment is climate, consisting of long-term weather patterns over large geographical areas. One important example of such variation is the monsoon, seasonal variations in wind patterns between oceans and continents. In modern times, the El Niño Southern Oscillation occurs with a period of several years when a large, semi-permanent tropical low pressure area shifts into the Central Pacific region from its more common location in the vicinity of Indonesia. This shift modifies prevailing winds, changes the pattern of ocean currents, and affects upwelling of ocean nutrients with profound effects on weather, rainfall, and fish and bird life over a vast area of the Pacific from Australia to the west coasts of South and North America.

3 El Nino phenomenon and its effects El Nino event is generally characterized by warming of the coastal waters off the coasts of Peru and Ecuador. Under normal conditions, these waters are held by relatively cool by upwelling activity typical of this region of the eastern pacific.

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5 El Niño is the warm phase of the El Nino Southern Oscillation (commonly called ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (between approximately the International Date Line and 120 W), including off the Pacific coast of South America. El Nino Southern Oscillation refers to the cycle of warm and cold temperatures, as measured by sea surface temperature, SST, of the tropical central and eastern Pacific Ocean.

6 El Niño is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific. The cool phase of ENSO is called "La Niña" with SST in the eastern Pacific below average and air pressures high in the eastern and low in western Pacific. The ENSO cycle, both El Niño and La Niña, causes global changes of both temperatures and rainfall. Mechanisms that cause the oscillation remain under study.

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8 Human Modifications of Climate Although Earth s atmosphere is huge and has an enormous ability to resist and correct for detrimental change, it is possible that human activities are reaching a point at which they may be adversely affecting climate. Microclimate The climate that organisms and objects on the surface are exposed to close to the ground, under rocks, and surrounded by vegetation, is often quite different from the surrounding macroclimate. Such highly localized climatic conditions are termed the microclimate. On the south-sloping portions of the terrace, the net effect has been to extend the short summer growing season by several days, thereby significantly increasing crop productivity. In areas where the growing season is longer, better growing conditions may exist on a north slope because it is less subject to temperature extremes and to loss of water by evaporation and transpiration.

9 Effects of Urbanization on Microclimate A particularly marked effect on microclimate is that induced by urbanization. In a rural setting, vegetation and bodies of water have a moderating effect, absorbing modest amounts of solar energy and releasing it slowly. The stone, concrete, and asphalt pavement of cities have an opposite effect, strongly absorbing solar energy, and reradiating heat back to the urban microclimate. Rainfall is not allowed to accumulate in ponds, but is drained away as rapidly and efficiently as possible. Human activities generate significant amounts of heat, and produce large quantities of CO 2 and other greenhouse gases that retain heat. The net result of these effects is that a city is capped by a heat dome in which the temperature is as much as 5 C warmer than in the surrounding rural areas, such that large cities have been described as heat islands. The rising warmer air over a city brings in a breeze from the surrounding area and causes a local greenhouse effect that probably is largely counterbalanced by reflection of incoming solar energy by particulate matter above cities. Overall, compared with climatic conditions in nearby rural surroundings, the city microclimate is warmer, foggier, overlain with more cloud cover a greater percentage of the time, and subject to more precipitation, though generally the city microclimate is less humid.

10 Air pollution is the presence of substances in air in sufficient concentration and for sufficient time, so as to be, or threaten to be injurious to human, plant or animal life, or to property, or which reasonably interferes with the comfortable enjoyment of life and property.

11 Air pollutants arise from both man made and natural processes. Pollutants are also defined as primary pollutants resulting from combustion of fuels and industrial operations and secondary pollutants, those which are produced due to reaction of primary pollutants in the atmosphere. The ambient air quality may be defined by the concentration of a set of pollutants which may be present in the ambient air we breath in. These pollutants may be called criteria pollutants. Emission standards express the allowable concentrations of a contaminant at the point of discharge before any mixing with the surrounding air.

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13 Introduction Air pollution may be described as contamination of the atmosphere by gaseous, liquid, solid wastes or by-products that can endanger life, attack materials and reduce visibility. Air pollution worldwide is a threat to human health and the natural environment. It may also be defined as the presence of matter in atmosphere at concentrations, durations, and frequencies that adversely affect human health and environment.

14 Introduction Air pollution can be caused due to the burning of wood, coal, oil, petrol, or by spraying pesticides. Some of the questions which might come to thinking about air pollution are: Are we doing something about solving these problems? mind while Do we know enough about the conditions under which a pollution episode occurs? What are the regulations? How to control emissions?

15 Should we worry about Air Pollution? Air pollution affects every one of us. Air pollution can cause health problems and in an extreme case even death. Air pollution reduces crop yields and affects animal life. Air pollution can damage monuments. Air pollution can cause significant economic losses. In short, air pollution does not only damage air; it also damages environment on earth s surface and their inhabitants.

16 History of Air Pollution in the US The problems of air pollution in Los Angles, New York city, and Chicago during the fifties drew attention of regulators in the United States. Conventional pollutants due to auto emissions and smoke stacks were the major thrusts of air pollution during the sixties and seventies. Invisible emissions of toxic pollutants were recognized in the late seventies. In early eighties scientists observed a slow down in growth of red spruce in the mountain areas of north-eastern US as a result of acid rain. In early nineties standards for ozone air pollution and sulfur dioxide has been revised In late nineties standard for particulate matter pollution was strengthened.

17 History of Air Pollution in the US In 2000, EPA passed a new rule for diesel, capping sulfur levels in diesel fuel at 15 parts per million by In 2005, EPA issued the Clean Air Interstate Rule (CAIR), to achieve the largest reduction in SO 2 & NO X from the atmosphere in the eastern United States. In 2006, EPA issued the strongest National Air Quality Standards for particle pollution in the country s history. In 2010 (January 6 th ), EPA has proposed to strengthen the National Ambient Air Quality Standards for ground-level ozone.

18 Air Quality Standards Achievement Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan

19 Accidents and Episodes day fog in Meuse Valley, Belgium day fog in Manchester, England Plant emissions in Donora, Penn, US day fog in London, England Radionuclide emissions, Three Mile Island, US Release of Methyl isocynate in Bhopal, India Radionuclide releases, Chernobyl, Ukraine 1997 Haze disaster in Indonesia 2001 Wildfires in Sierra Nevada, US 2001 Enormous clouds of dust in New York during Collapse of World Trade Center, US 2002 Violent dust storm in Queensland, Australia Jilin chemical plant explosions, Jilin city, China 2007 Wildfires in TALLAHASSEE Florida, US Kingston Fossil Plant coal fly ash slurry spill, Kingston, US

20 Eras of Air Pollution Early-Industrial Era Pre-Industrial Era Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan Early 20 th Century Late 20 th Century Early 21 st Century

21 Air Pollutant Contaminant that affects human life, plant life, animal life and property could be termed as an air pollutant. Air pollutants are classified into two categories: Primary pollutants: These pollutants are emitted from a source directly into the atmosphere. e.g. Sulfur dioxide and Hydrocarbons Secondary pollutants: These are formed due to the chemical reaction among two or more pollutants. e.g. Peroxyacetyl nitrate (PAN )

22 How to Define an Air Pollutant? Basis: Chemicals present in the environment Process: Use composition of the clean air as a bench mark. When the concentration of a chemical in air is above the bench mark, it is termed as an air pollutant.

23 Chemical Composition of Dry Air Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan

24 Common Air Pollutants The air pollution problem is encountered in both indoor as well as outdoor. Indoor Radon Combustion by-products CO, CO 2, SO 2, Hydrocarbons, NOx Particulates, Polyaromatic hydrocarbons Environmental Tobacco Smoke (ETS) Volatile organic compounds Asbestos Formaldehyde Biological contaminants Pesticides Outdoor SO 2 CO, CO 2 Oxides of Nitrogen Ozone Total Suspended particles Lead Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan Particulates Volatile organic compounds Toxic Air pollutants

25 Indoor Outdoor Sources of Air Pollutants Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan

26 Physical Forms of an Air Pollutant Gaseous form o Sulfur dioxide o Ozone o Hydro-carbon vapors Particulate form o Smoke o Dust o Fly ash o Mists

27 Toxic Air Pollutants Toxic air pollutants may originate from natural sources as well as from manmade sources such as stationary and mobile sources. The stationary sources like factories and refineries serve as major contributors to air pollution. The Clean Air Act of 1990 provides a list of 189 chemicals to be regulated under the hazardous air pollutant provisions of the act. The list of hazardous air pollutants can be found in the EPA website. (

28 Sources of Toxic Air Pollutants Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan

29 Toxic Air Pollutants The toxic air pollutants released from industrial facilities, in the United States, are reported to the public via the Toxic Release Inventory (TRI) USEPA Major sources are defined as sources that emit 10 tons per year of any of the listed toxic air pollutants, or 25 tons per year of a mixture of air. Area sources are defined as sources that emit less than 10 tons per year of a single air toxic, or less than 25 tons per year of a mixture of air toxics.

30 Units for measurement of Air Pollution There are two units of measurement. They are as follows: µg/m 3 and ppm (parts per million) At 25 C and 1 atm At 0 0 C and at a pressure of 76 cm of Hg, volume of the air is l/mol. To obtain volume at any temperature, use gas law P 1 V 1 /T 1 = P 2 V 2 /T 2 Dr. Muhammad Asif Hanif, Department of Chemistry, University of Agriculture, Faisalabad, Pakistan

31 Sources of Air Pollution Natural Sources Volcanoes Coniferous forests Forest fires Pollens Spores Dust storms Hot springs Man-made Sources Fuel combustion - Largest contributor Chemical plants Motor vehicles Power and heat generators Waste disposal sites Operation of internal-combustion engines

32 Natural Sources vs. Man-made Sources Pollutants released from natural sources like volcanoes, coniferous forests, and hot springs have a minimal effect on environment when compared to that caused by emissions from man-made sources like industrial sources, power and heat generation, waste disposal, and the operation of internal combustion engines. Fuel combustion is the largest contributor to air pollutant emissions, caused by man, with stationary and mobile sources equally responsible.