A commitment by Japan to slash greenhouse gas emissions to net-zero by 2050 suggests the closing of another door for Australian coal exports and poses a warning sign for LNG, although fledgling efforts on hydrogen could be accelerated.

The pledge, announced by new Prime Minister Yoshihide Suga on Monday in his first policy speech in parliament, represents a major strengthening of Japan's previous commitment to reduce emissions by 80 per cent by mid-century.