Because significant volumes of earth must be displaced to mine coal, coalmines and the resulting rock waste [2] can harm the environment. Furthermore, burning coal releases environmentally harmful chemical compounds into the air.

15-1 Mining and Mining Waste

Surface mining has resulted in a great deal of damage to the landscape [3]. Many surface mines have removed acres of vegetation and altered topographic features [4], such as hills and valleys, leaving soil exposed for erosion. Longwall mining, which allows the mine to collapse, results in widespread land subsidence [5], or sinking. Coal and rock waste, often dumped indiscriminately [6] during surface and underground mining processes, weathers rapidly, producing acid drainage [7]. Acid drainage contains sulfur-bearing compounds [8] that combine with oxygen in water vapor to form sulfuric acid. In addition, weathering of coalmine waste can produce alkaline compounds [8], heavy metals [9], and sediments. Acid drainage, alkaline compounds, heavy metals, and sediment leached from mine waste into groundwater [10] or washed away by rainwater can pollute [11] streams, rivers, and lakes.

Today, enterprises in many countries must secure government permits before mining for coal. In the United States, mining companies must submit plans detailing proposed methods for blasting, road construction, land reclamation [12], and waste disposal [13]. New land reclamation methods, driven by stringent [14] laws and regulations, require coal mining companies to restore strip-mined landscapes to nearly premined conditions.

15-2 Burning Coal

The burning of coal produces environmentally harmful emissions. Some gases produced from burning coal, such as carbon dioxide, are known as greenhouse gases [15] because they trap the Earth��s heat like the roof of a greenhouse and may contribute to global warming [16]. Other emissions from coal combustion [17] can lead to air and water pollution.

A. Greenhouse Effect [18]

Earth absorbs much of the heat energy radiated from the Sun. The planet then reradiates this heat back into the atmosphere. Carbon dioxide and some other gases that are naturally present in the atmosphere prevent much of the heat from escaping back into space, maintaining Earth at a temperature that can support life. These gases are known as greenhouse gases because they trap the Sun��s heat in much the same way as the glass roof of a botanical greenhouse [19]. However, the immense quantity of fossil fuels burned during the world��s rapid industrialization [20] over the last 200 years has raised levels of carbon dioxide in the atmosphere by about 28 percent. This dramatic increase in atmospheric carbon dioxide, coupled with continuing depletion [21] of the world��s forests, which absorb carbon dioxide, has led many scientists to predict a heating of the atmosphere on a global scale. Such a global warming could disrupt [22] weather patterns, cause the po

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