The burning of fossil fuels represents the most significant contributor to climate change, the report, titled The Critical Decade 2013 states.

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

“From today until 2050 we can emit no more than 600 billion tonnes of carbon dioxide to have a good chance of staying within the 2 degrees Celsius limit.

“Based on estimates by the International Energy Agency, emissions from using all the world’s fossil fuel reserves would be around five times this budget.

“Burning all fossil fuel reserves would lead to unprecendented changes in climate so severe that they will challenge the existence of our society as we know it today.”

Major changes to the ways in which energy is produced are needed, the report states.

It says most of the world’s known fossil fuel reserves will have to be left in the ground if the world is serious about respecting the 2C limit.

“Increasing fossil fuel emissions are largely from burning of coal, which also constitutes the majority of potential emissions from fossil fuel reserves,” the report says.

“Australia’s coal reserves alone represent about 51 billion tonnes of potential CO2 emissions, or around one-twelfth of the 600 billion tonne global budget.

“Growth in the use of coal will need to be turned around so that it makes up a much smaller proportion of the global energy mix and eventually not used at all.”

The commission’s report states that storing carbon in soils and vegetation is part of the solution but cannot substitute for reducing fossil fuel emissions.

“How quickly we must reduce emissions is closely related to when emissions ‘peak’ – that is when they are at the highest levels,” the report states.

“In 2013 emissions are still rising by about 3 per cent per year, so they are still on a strongly upward trajectory.

“If emissions could somehow peak in 2015, just two years away, the maximum rate of emission reductions thereafter would be 5.3%, a very daunting task.

“However, if we allow emissions to continue to rise through the rest of this decade and don’t reach the peaking year until 2020, the maximum rate of emission reductions thereafter is 9%, a virtually impossible task unless economies around the world prioritise emission reductions above all other economic and technological goals.”