Australian coal mining companies have been shelving greenfield projects in favor of increased extraction at existing mines. Companies, especially those that are not protected by diversification, would rather extract more from existing projects than initiate new projects that could be stymied by future economic or regulatory conditions.
Coal mining in Australia is threatened by low prices, which are the result of increased production and decreased demand in recent years (especially in China). This threat is made worse by increasing opposition to mining development by environmentalists, local communities, and some politicians. For detailed analysis of the situation, check out http://www.fool.com.au/2013/09/14/what-future-for-coal-mining-in-australia/