Despite the abundance of natural gas in the U.S. and Europe’s efforts to reduce greenhouse gas emissions, coal, the fastest-growing fossil fuel, met 30.1 percent of the world’s energy demands last year, its highest share since 1970, according to BP’s Statistical Review of Energy unveiled Thursday.

The rapidly growing economies of China and India accounted for 88 percent of global growth in coal consumption, which saw a 3 percent rise in 2013, while growth in natural gas consumption actually decelerated everywhere except North America, according to the review. There are several reasons: Coal is relatively abundant around the world, it's cheap to burn compared to other methods of generating electricity, and in the past two years prices for coal have declined.

The strong demand for coal shows how difficult it will be to replace as efforts by developed nations to reduce pollution and add renewable energy to their power grids will be overwhelmed by the growth of developing nations relying on coal.