Most fossil fuels must remain in the ground because burning them will unleash changes that will “challenge the existence of our society”, a new Australian government agency report warned Monday.

The Climate Commission study found that the burning of fossil fuels such as coal, a key Australian export, represented the most significant contributor to climate change.

“Burning all fossil fuel reserves would lead to unprecedented changes in climate so severe that they will challenge the existence of our society as we know it today,” said the report, The Critical Decade.

“It is clear that most fossil fuels must be left in the ground and cannot be burned.”

Most nations, including Australia, have agreed that the risks of the climate changing beyond two degrees Celsius are unacceptably high.

But to ensure the climate is stabilised, the world must “virtually decarbonise”, the report said.

Australia's coal reserves alone represent about one-twelfth of the 600 billion tonnes which, if emitted, are thought would push temperatures above the two degrees Celsius threshold, it said.

But Australia's Resources Minister Gary Gray said while it was important to invest in clean energy technologies, coal was vital to the economy.

The minister said developing countries such as India and China were reliant on Australian coal for energy.AFP

Developing countries such as India and China are reliant on Australian coal for energy