Coal demand in Japan, Australia’s biggest export market, could plunge by more than half over the next two decades, according to projections from the International Energy Agency (IEA).

In its annual World Energy Outlook the agency modelled the impact of cutting world carbon emissions to 450 parts per million, a level needed to avoid “catastrophic’ climate change. It found that in Japan, the cuts would cause total coal demand to fall by 60 percent to about 44 million tonnes in 2030.

By comparison, China’s demand for coal would continue to increase, however, it would still be 43 percent lower than if emissions were allowed to keep climbing.

The figures show the massive changes to the world’s energy mix required to meet emissions cuts, which the IEA said would be “achievable but very challenging.” Making the cuts would cost an extra $10.5 trillion in global investment by 2030, but the IEA said failure to act would lift global temperatures by up to 6 degrees.