With increased public and environmental awareness, and the introduction of reclamation and environmental laws over the last few decades, mining practices have changed to reduce or mitigate environmental impacts. Many nations, particularly those with a long history of coal mining, have rules and regulations tailored for the mining industry. Millions of dollars are spent annually in regulatory compliance efforts which include reclamation activities at surface mines. In contrast to their predecessors, mine operators in many nations are required to meet regulatory compliance in all phases of the operation. Governmentally approved mining and reclamation plans must be filed prior to opening a coal mine. Within the United States, reclamation is required by both state law and by the federal Surface Mining Control and Reclamation Act (SMCRA). Governmental regulations are in force to minimize the effect coal utilization have on our air, land, and water. For example, the 1990 Clean Air Act Amendments in the United States have given utilities until the year 2000 to reduce the emissions of SO2 to a maximum of 0.54 kg (1.2 lb) per million Btu (British Thermal Unit). In addition, international global warming conferences, such as those held in Rio de Janeiro, Brazil and Kyoto, Japan in 1997, will undoubtedly have a future impact on the mining business and world economies.