With the world's temperature predicted to hit 4C-6C by 2100, the International Energy Agency (IEA) has urged on the global federal governments to abolish the fossil fuel subsidies as it believed this would greatly lead to reduce carbon emissions.

"Measures that encourage inefficient use of energy, such as fossil fuel subsidies, must be eliminated," Maria van der Hoeven, IEA Executive Director, said at the 18th Conference of Parties to the UN Framework Convention on Climate Change (COP 18) in Doha.

On Monday, Dr Pep Canadell, a leading Australian climate scientist, said the world's temperature will hit a baking 4C-6C by end of the century.

"IEA analysis shows that achieving the internationally agreed climate goal of limiting warming to two degrees celsius is becoming more difficult and more expensive with every passing year," Ms van der Hoeven said.

But the 4C-6C forecast is a very unsettling prospect, she said.

"The IEA strongly encourages all governments to enact policies that promote the rapid deployment of energy-efficiency technologies; this would reduce greenhouse gas emissions and buy time to secure a much-needed global climate agreement," the IEA director said.

As the UN climate talks entered into a second week without no agreement still in place, Ms van der Hoeven said it is "more urgent than ever" to already switch to a more secure, sustainable global energy system.

Nations participating in the Doha talks were in disagreement on whether to concede to allow individual nations to hold on to unused emissions quotas. The disagreement eventually delays the extension of the Kyoto Protocol on curbing emissions of Earth-warming gases, primarily carbon dioxide which results from burning fossil fuels.

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Global Temperature to Rise 4C-6C by 2100, Says Leading Australian Climate Scientist