Short answers, pulled from the story.
The late Carboniferous period spanned roughly 359 to 299 million years ago. Vast wetlands covered much of the tropics where lycophyte trees accumulated organic matter that transformed into coal deposits through a process called coalification.
Subbituminous coal could form at temperatures as low as 60 degrees Celsius while anthracite required temperatures of at least 270 degrees Celsius. Temperature proved far more critical than pressure or time in determining the final grade of coal produced during burial.
Neolithic inhabitants near Shenyang began carving ornaments from black lignite around 4000 BC. The oldest intentional use of black coal dates back to a settlement on Landek Hill in Ostrava, Petřkovice, between 25,000 and 23,000 years BC.
By 1947 approximately 750,000 miners worked in British mines before the last deep coal mine closed in 2015. In 1700 five-sixths of the world's coal came from Britain alone before consumption patterns changed with the Industrial Revolution.
Over fifteen billion tonnes of carbon dioxide emitted from burning coal in 2024 represented more than a quarter of all global greenhouse gas emissions. Coal-fired power plants were the single largest contributor to global CO2 emissions growth in 2018 accounting for 40 percent of total fossil fuel emissions.