An analysis of the planet's 14 largest proposed, coal, oil and gas developments - to be released on Wednesday by Greenpeace - finds if Australian coal production expands as projected, the mining, production and burning of the extra resource would, by 2020, result in 759 million tonnes of new global carbon dioxide emissions a year over 2011 levels.

But emissions from Australian coal growth would be eclipsed by proposed coal production in western China, projected to result in 1400 million tonnes of annual CO2 emissions by 2020.

Greenpeace says development of the 14 fossil fuel projects would put significant pressure on the world's ability to meet a target, agreed to by nations through the United Nations, to limit global warming to a global average of two degrees.

''Burning the coal, oil and gas from these 14 projects would significantly push emissions over what climate scientists have identified as the 'carbon budget', the amount of additional CO2 that must not be exceeded if we are to keep climate change from spiralling out of control,'' the report says.

Based on new analysis by the British sustainability consultancy Ecofys, Greenpeace says fossil fuels from the 14 projects would contribute in 2020 the same emissions as the entire United States.

All up the report says by 2020 the 14 fossil fuels developments would result in an extra 6.34 billion annual tonnes of global carbon dioxide emissions. By 2050 total new emissions would reach a little over 300 billion tonnes.

The underlying Ecofys analysis says if new fossil fuels projects are fully developed, emissions would need to peak by 2019 to afford a 50-50 chance of keeping climate change to two degrees. If new fossil fuel development is avoided, emissions can peak later in 2025 before rapid cuts are needed.

Of the total amount of estimated global emissions that can be released by 2050 to have a 50 per cent chance for two degrees, new fossil fuel developments would eat up 20 per cent. Of the emissions allowed to have a 75 per cent chance of two degrees of warming, the proposed fossil fuel expansions would account for 30 per cent.

While the global carbon implications of Australian coal expansion is less than China, the report says it would be bigger than the well-publicised development of tar sands in Canada.

With a carbon tax now in place to price domestic emissions, environmentalists are increasingly trying to shift a spotlight onto the contribution of Australia's coal exports to global warming. The vast majority of emissions from exported coal are not counted under Australia's greenhouse gas targets, and is instead recognised in the country it is burnt.

Ecofys says the analysis is based on present fossil fuel industry plans being realised, and should not be considered the most likely outcome of what may actually be developed.

The analysis includes exports of Australian coal for use in both electricity and steel production.

The UBS global commodity analyst Tom Price said: ''[As a] rule of thumb, in forecasting supply growth in any commodity market, whatever the market in total expects in terms of supply delivery, you can pretty much expect only 50 per cent of it turns up''.