SYDNEY—An international agreement to reduce coal use dragged miners’ shares lower on Monday, but the tight supply of the commodity provided a floor for a sector that has chalked up huge gains this year. U.N. climate talks in Glasgow ended on Saturday with a deal targeting fossil fuel use. Wording was softened to call for a “phase down” rather than “phase out” of coal after lobbying from China and India, among others. Big miners China Shenhua Energy and Yanzhou Coal fell 1 percent and 2.4 percent respectively in Hong Kong, where the broader stock market edged up slightly. An index of mainland-listed miners fell about 1 percent. Coal stocks in other regions also came under pressure. In Indonesia, the world’s biggest coal exporter, declines were exacerbated by surging production in China, a top customer. No. 1 miner Bumi Resources fell 5.7 percent, while Adaro Energy and Indika Energy tumbled 4.5 …