Environmental preservation activists on Wednesday warned Indonesia of an unbearable cost to its future caused by massive coal exploitation, which has been boasted as a significant contributor to its Gross Domestic Product (GDP) and economy growths. The warning was issued by activists joining the international environmentalist organization Greenpeace who staged a demonstration in front of the office of the Coordinating Minister for the Economy here on Wednesday. If compared to the costs incurred by environmental damage caused by massive coal mining activities in the country, contribution of coal commodity to national GDP was only 4 percent with very limited prospect in the future despite enormous growth of coal production and export, said the activists. Though deemed as a main propeller of the country's economy, coal mining was a low-valued industry that eventually causes excessive damages to the cycle of people's way to make a living, they said. "Development on coal basis would not help people in poor rural areas because it severely exacerbates agriculture, fishery and other sectors that many people have been depending on," Arif Fiyanto, Greenpeace campaigner for climate and energy issue said. He added that government should stop economy development that largely sourced from coal because it may further damage the environment and disrupt people's health. "In the long run, should Indonesia continue its economy development on coal basis, the coal itself would destroy its economy and makes the country secede apart from low-carbon economy development drive," he said. Indonesia is one of world's largest coal producers with almost 80 percent of its production designated for exports. According to data released by Indonesian Coal Miners Association (APBI), Indonesia's total coal production was 400 million tons last year, of which 65 million tons were for domestic usage. Indonesia was ranked as the world's third largest coal producer and the largest coal exporter. APBI Chairman Bob Kamandanu said earlier that Indonesia deposits at least 168 billion tons of coal from various qualities with confirmed reserves of 28 billion tons, located in Sumatra, Kalimantan, Sulawesi, Papua and small part in Java. Coal, along with other mineral products such as tin, nickel, gold and coppers, contributed 11 percent, or 93 billion U.S. dollars, to Indonesia's GDP last year.