The Intergovernmental Panel on Climate Change, or IPCC, will meet next week in Berlin to chart ways in which the world can curb the greenhouse gas emissions that scientists say are overheating the planet.
It is also trying to give estimates on what it would cost. In the third report of a landmark climate assessment, the IPCC is expected to say that to keep warming in check, the world needs a major shift in investments from fossil fuels - the principal source of man-made carbon emissions - to renewable energy.
"And there will also be some discussions of how deep global cuts are needed to put us onto these different climate trajectories."
A leaked draft of the report sent to governments in December suggests that in order to keep global temperature increases below 2 degrees Celsius by the end of the century - the stated goal of international climate talks - emissions need to fall by 40-70 per cent by 2050.
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That message is likely to face opposition from the fossil fuel industry and countries that depend on it.
Earlier this week, Exxon Mobile said the world's climate policies are "highly unlikely" to stop it from selling fossil fuels far into the future.
That contrasted with a message from UN climate chief Christiana Figueres, who told oil and gas industry officials in London on Thursday that three-quarters of the fossil fuel reserves still in the ground needs to stay there for the world to achieve the 2-degree target.
The alternative plan to mitigate climate change would involve coming up with new ways to scrub carbon out of the atmosphere or prevent too much sunlight from being trapped in the atmosphere by greenhouse gases.