With countries from China to Brazil lining up to showcase efforts to rein in pollution that causes global warming, developers of coal power plants in Japan may find themselves increasingly under pressure.

Japan formalized last Friday a target to cut climate-warming gases by 26 percent by 2030 from 2013 levels. The plan is built on the assumption coal will generate about a quarter of the country's electricity by that time.

The country's declining population and an oversupply of coal power plants risk undermining investments in new coal-fired capacity. Pressure to sell out of stakes in fossil fuel may also play a role in making coal investments less appealing, environmentalists and analysts say.