Explanation:

About 70 fires have sprouted up at eastern India's Jharia coal fields, which cover more than 100 square miles and have been mined since the late 1800s. The first recorded coal fired broke out in 1916, and fires have burned there ever since. It is just one of the thousands of coal fires that are burning around the world — a costly and dangerous phenomenon involving a fuel source that has helped power economic development but is under attack in the age of global warming. Many of the fires are believed to have started through spontaneous combustion or what is sometimes called self-heating, caused by the oxidation of minerals in the exposed coal. Much of the mining at Jharia is done at the surface, exposing the coal to open air. Certain varieties of coal contain minerals that heat up when they are exposed to oxygen; those minerals can in turn burst into flames.