Class Session 18>

I. Acid Rain
The phenomenon known as acid rain is one of the most damaging and controversial forms of air pollution in the industrialized world. Emissions of sulfur dioxide (SO2) and nitrogen oxide (Nox) along with other compounds involved in acid-base chemistry, such as ammonia and alkaline dust particles, are responsible for the phenomenon known as acidic deposition or more popularly as acid rain. Acidic deposition can take several forms, including rain, sleet, snow, fog, and dry particles. The primary sources of acid deposition are sulfur and nitrogen oxides released from electrical power plants, industrial boilers, mineral smelting plants, and motor vehicles that burn fossil fuels.

Acidity is measured on the pH scale, which ranges from 0 to 14, with 0 being acid, 7 as neutral, and 14 as alkaline. It is important to remember that the pH scale is logarithmic, so that a change in one unit represents a tenfold change in acidity, thus a solution of pH 4 is 10 times as acidic as one with pH 5 and 100 times as acidic as pH 6. "Natural" rainfall, or rain that does not contain gases or compounds released by humans is slightly acidic and generally has a pH of between 5 and 6. Once SO2 and NOx combine with moisture in the atmosphere, they return to earth as diluted forms of sulfuric and nitric acid. In many of the heavily industrialized regions of the world, the pH of precipitation averages around 4, over ten times as acidic as natural rainfall .

The effects of acid rain are generally classified into three categories: aquatic, terrestrial, and materials. Acid rain, or more correctly acidic deposition, does not affect all ecosystems in the same way. Soil and water types vary a great deal. The American Midwest, for example, has naturally alkaline soils that can buffer acid fallout. Likewise, some lakes lie on limestone, sandstone, or other alkaline formations that help neutralize the acid. On the other hand, some regions where lakes and soils lie on granite or glacial tills have low pH values to begin with and thus are greatly affected by acid rain.

The aquatic effects that stem from acid rain result from the increasing acidity of natural waterways. Plants and other components of aquatic ecosystems have a preferred and tolerated range for acidity in the environment. If the acidity is greater than what they can tolerate, the ecosystem gets stressed and eventually can disappear.

In Sweden, thousands of lakes have been damaged from the effects of acid rain. A similar situation exists in Norway, where a high percentage of the lakes have been declared technically "dead" or placed on the critical list. Closer to home, hundreds of lakes in Ontario, Canada low pH levels, as do many of the rivers in Nova Scotia. In the U.S., thousands of lakes and rivers on the eastern seaboard have high acidic content.

The St. Mary's River in Maryland, long considered one of the best trout rivers in the state, has become inhabitable for fish due to the long-term effects of acid rain. A plan is currently underway, in fact, to dump 140 tons of limestone in the headwaters and tributaries of the St. Mary's River in an effort to reduce the acidic level of the river and encourage restoration of aquatic ecosystems.

Acid rain also affects land-based or terrestrial ecosystems. In Switzerland and Germany, for example, extensive stretches of their forests have been damaged or destroyed by acid rain. Extensive vegetation dieback and soil erosion have occurred in the in the Canadian province of Ontario and acidic deposition has been implicated in tree damage reaching all the way down to the Appalachian mountains in Georgia in the U.S.

Materials and structures are also affected by acid rain. The most common problem is corrosion of buildings and statues made of marble and limestone. Steel structures are also susceptible to corrosion resulting from acid rain. In Poland, where there are few or no emissions controls on smokestacks, and where they burn large quantities of high sulfur coal, acid deposition is beginning to erode railroad tracks.

One of the difficulties involved in dealing with acidic deposition is that it often falls in different areas or countries from where it originated. Sulfur dioxide emissions can travel up to 2,000 kilometers in a few days. Most of the acidic deposition in the eastern United States, for example, is the result of coal burning power plants in the Midwest. Acidic deposition has become a significant transboundary issue. Both Sweden and Norway claim that most of the SO2 they receive comes from other countries, most notably Poland.

A range of specific control technologies exists for both sulfur dioxide and nitrogen oxides. Since sulfur dioxide is produced primarily from the combustion of coal, there are a number of technologies designed to burn coal more cleanly. These include more efficient boilers, cleaning technologies, and fluidized combustion beds. Other technologies designed to reduce SO2 and NOx emissions include limestone injection burners, reburners, flue gas desulpurizes, in-duct sprayers, and low NOx burners.

In addition, technologies exist for both wet and dry deposition, monitoring and measurement as well as materials protection. Monitoring and measurement technologies include rain gauges and pH analyzers. Materials protection technologies include waxes, special coatings, and paints.

II. Global Warming
Global warming is caused by the release of several gases including carbon dioxide (CO2), methane (CH4), nitrous oxide (N20), and chloroflourocarbons (CFCs). The buildup of these gases over time is thought to be altering the heat absorption capacity of the earth's atmosphere and warming global surface and sea temperatures. The combustion of fossil fuels, along with other human economic activities including forestry and agriculture are largely responsible for the overconcentration of greenhouse gases in the atmosphere. Since many of the activities responsible for greenhouse gas emissions are central to urbanized, industrialized societies, reducing emissions is a challenging task.

In 1988, at least 6 billion tons of carbon were added to the atmosphere--about 5.5 billion tons from fossil fuel combustion and between 0.4 and 2.5 billion tons from burning or clearing forests, primarily in tropical areas. Of the portion attributed to fossil fuel use, the United States contributes about 24 percent of total emissions, the Soviet Union 20 percent, and Western Europe 15 percent. The United States, the Soviet Union and Europe together produce two-thirds of all carbon emissions from fossil fuels. Of the carbon emissions from deforestation, in 1980 Brazil accounted for roughly 20 percent .

Prior to the Industrial Revolution, the concentration of CO2 in the earth's atmosphere was 275 to 285 ppm. Since then, humans have burned vast quantities of fossil fuels -- coal, oil and natural gas -- releasing carbon gases and other emissions. As a result, atmospheric CO2 concentration is now 25 percent higher than before the Industrial Revolution, and increasing rapidly. In the last 30 years, the CO2 level has risen from 316 ppm to about 360 ppm, the highest concentration in the past 160,000 years. Data from ice cores and ocean sediments show a clear link between atmospheric carbon dioxide and global temperatures over this period; higher CO2 concentrations have coincided with higher temperatures.

Other gases such as methane (CH4), chlorofluorocarbons (CFCs), tropospheric ozone, and nitrous oxide also contribute to global warming. Although trace gases make up only a small percentage of the total atmosphere, some trap heat a thousand times more effectively than CO2. Their effect is compounded because they absorb different wavelengths of infrared radiation.

Methane (CH4) is released into the atmosphere by a variety of pro-cesses, the most prominent being anerobic fermentation by ruminants, release from both natural wetlands and rice fields, biomass burning, coal mining operations and leak-age of natural gas during transmission. A number of anthropogenic sources of N20 have been identified. These include fossil fuel combustion and biomass burning. Recently, scientists have discovered large amounts of N20 in the upper atmosphere as well as tropical waters of the Pacific.

The concentration of trace gases in the atmosphere is increasing even faster than that of CO2, and is thought to be responsible for about half of the additional warming. There is considerable uncertainty about the relative contributions of the various greenhouse gases to global warming, but estimates are available. During the past decade, methane has probably accounted for about 16 percent of global warming, with much of the methane coming from rice and cattle production, decomposition of organic wastes, and the burning of fossil fuels and forests. The release of CFCs and other halocarbons, the same gases that are destroying the ozone layer, may account for about 20 percent of greenhouse warming .

The National Oceanic and Atmospheric Administration (NOAA) scientists released a report in November 2000 that examined year-by-year temperatures trends for the past several centuries. The research group examined ice core, tree ring, coral, and sediment data, as well as historical records and concluded that “While the natural - solar and volcanic - forcings appear to be important factors governing the natural variations in temperatures in past centuries, only human greenhouse gas forcing alone….can statistically explain the unusual warmth of the past few decades”.

The Intergovernmental Panel on Climate Change issued its third Scientific Working Group Report in January 2001. The report concluded the following:

* The global average surface temperature increased .6 degrees centigrade in the 20th century.

* The 1990’s were the warmest decade since record keeping began in 1861.

* 1998 was the warmest year since record keeping began in 1861.

* The Northern Hemisphere temperature rise since 1900 is the most of any century for the past 1,000 years.

* On average, night-time daily minimum temperatures over land increased by a rate of .2 degrees centigrade per decade between 1950 and 1993, about twice the rate of daytime daily maximum air temperatures.

* Artic sea-ice thickness during late summer and early fall has declined 40% in recent decades.

* Snow cover in the Northern Hemisphere, has decreased by about 10% since the late 1960s.

* Duration of lake/river ice in the Northern Hemisphere has shortened by about 2 weeks since 1900.

In addition to the empirical observations of past climate change, the IPCC Third Assessment Report also included the following projections:

* An increase in the globally averaged surface temperature by 1.4 - 5.8°C from 1990 to 2100.

* Rise in global sea level of between 0.09 to 0.88 meters from 1990 to 2100.

* Increase in global average water vapor concentrations and precipitation, as well as more intense precipitation events are likely over many northern hemisphere's mid- to high-latitude land areas.

The U.S. National Academy of Science released a report in December 2001, which concluded that warming of the atmosphere, due to emissions of greenhouse gases, could occur in a stepwise, rather than linear fashion. The implications of this report are that future warming could occur abruptly, changing temperatures drastically over the span of a few decades.

Every year since 1994, the World Meteorological Organization (WMO) has been giving annual updates on the world’s global climate. In December 2001, WMO reported that the global average surface temperature for 2001 was expected to be 57.96 degrees, second only to 1998’s record high of 58.24 degrees. Further, WMO reported that nine of the ten warmest years on record since 1861 occurred in the 1990s and that rate of global temperature increase tripled during the 20th century. This past December, WMO reported that the year 2002 had surpassed 2001 for warmth, with 1998 still being the warmest year on record.

Many types of effects could result from a warmer global climate. These include regional climatic shifts, changes in existing patterns of precipitation, sea level rise, and accelerated species extinction. It is also thought that higher levels of carbon dioxide may benefit plants by accelerating the process of photosynthesis, although some plant species will adapt better than others. It is also though that global warming will favor warm-weather insect species with short life spans that can adapt and evolve quickly and that insect pests, parasites, and pathogens might flourish under rapid warming conditions.

In December 1997, an international accord was signed in Kyoto, Japan to develop strategies to reduce greenhouse gas emissions. Subsequently, a meeting to devise implementation strategies for greenhouse gas reduction programs was held in Buenos Aires. The United States, the global leader in greenhouse gas emissions, was a signatory to the Kyoto Treaty and federal and state legislators across the U.S. had been working to develop acceptable greenhouse gas reduction strategies. On March 13 2001, four U.S. senators wrote a letter to President Bush expressing their opposition to limits on carbon dioxide. One week later, President Bush reversed a campaign pledge to seek greenhouse gas emissions reductions and removed the U.S. as a signatory to the Kyoto Protocol. In February 2002, the U.S. Administration unveiled its proposed plan to reduce greenhouse gas emissions. The plan centers substitutes flexible targets for the fixed targets set by Kyoto. The flexible targets are known as emission intensity targets. The goal of the President’s plan is to reduce the greenhouse gas intensity of the U.S. economy by 18% over the next ten years. In addition, the plan also increased funding for scientific research.

The Kyoto Protocol requires two conditions be met for it to enter into force. First, 55 countries must ratify the Protocol. This was achieved last year. Second, ratifying governments must be represented by developed countries responsible for a minimum of 55 per cent of 1990 CO2 emissions. Currently, developed country ratifications account for 43.9 per cent of 1990 CO2 emissions. There are several smaller, mostly industrialized countries, and countries with economies in transition, in the process of ratification. The total emissions for which they account are not enough to reach the needed 55 per cent of developed country emissions. As of this time, 102 countries have ratified the Kyoto Protocol, but it is Russia that will determine when, or if, the Protocol comes into force. The Protocol has recently passed both houses of the Russian Parliament, and is awaiting President Putin’s signature.

III. Current State of Emissions
For starters, global energy use is projected to be 607 quadrillion BTUs by the year 2020 and fossil fuels are projected to continue to dominate the global fuel mix. If this predicted trend in energy consumption proves true, global carbon dioxide emissions will grow from 5.8 billion metric tons carbon equivalent in 1999 to 7.8 billion metric tons in 2010 and 9.8 billion metric tons by 2020. Interestingly, developing countries account for the bulk of the projected increase in CO2 emissions, over 75%. In addition, the rate of worldwide energy and carbon emissions growth would be even greater except for continued improvements in energy consumption per dollar of gross domestic product, a measurement referred to as energy intensity, or energy efficiency

In addition to international and federal legislative initiatives to reduce greenhouse gas emissions, there are literally hundreds of processes and technologies that could be used to reduce greenhouse gas emissions either by controlling them or preventing the creation of the gases. Technologies used to reduce greenhouse gases include the following:

Energy Supply

 

Batteries & battery systems

Photovoltaics

 

Water Storage

Solar Thermal

 

End Use Technologies

Wind energy systems

 

Building energy controls

Hydroelectric equipment

 

Lighting

Wave & tidal energy

 

Windows

Geothermal conversion systems

 

Alternative Transportation

Water/steam/gas turbines systems

 

Electric Vehicle

Biomass technology

 

Solar Vehicles

Landfill gas utilization - Biogas engines & generators

 

Solar Electric Vehicles

Fuel cell technology

 

Hybrid Vehicles

Ocean Thermal Energy Conversion

 

Natural Gas Vehicles

Co-generation equipment & systems

 

Fuel Cell Vehicles

Fluidized-bed combustion

 

Public Transit

Energy Storage