My second post
The majority of the world's man-made carbon emissions are released by the burning fossil fuels to create electricity, heat or motion.
This means that it will almost certainly be impossible to reduce greenhouse gas concentrations to sustainable levels unless large quantities of low-carbon energy can be brought on-stream to substitute for fossil fuels.
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The two main sources of low-carbon energy are renewables – which includes categories such as solar, wind, hydro, biomass and marine energy – and nuclear. In terms of total primary energy supply (i.e. raw energy created), data for 2008 suggest that fossil fuels provided around 85%, nuclear contributed around 2% and renewables provided around 13%.