'Failure to success'
Talks in Copenhagen, which are aimed at agreeing the outline of a new climate treaty to succeed the Kyoto Protocol, are stuck on splitting the bill for cutting carbon emissions and preparing for more droughts, floods and rising seas.
Poorer nations want rich countries to spend one per cent or more of their national wealth on emissions cuts in the developing world, or at least $300bn annually, about double the closest estimates by industrialised countries.
Speaking on the sidelines of the conference, Soros said: "I've found a way for someone else to pay ... to mobilise reserves that are lying idle.
"The whole conference might break down because of this, and this $100bn fund I think could just turn this conference from failure to success."
The IMF made the SDRs available to help combat the global recession, by unlocking financial liquidity after panic froze debt markets - including more than $150bn for the 15 biggest developed economies, Soros said.
The billionaire said developing countries could make money from their low-carbon investments from the SDR fund by selling carbon credits on the carbon markets.
IMF gold reserves would guarantee the principle and interest.
Soros said he would invest $1bn of his own $25bn funds in low-carbon assets.
The Hungarian-US financier also acknowledged a series of obstacles to his proposal, including getting approval from the US Congress and the director general of the IMF, as well as global carbon prices.
"The IMF directors are not keen to use it [the gold reserve]. If you're on the board of directors you like to have this nice substantial reserve to sit on so they won't actually do this of their own free will," Soros said, adding political will was needed to drive his initiative.
Other ideas on the table to unlock climate finance include a levy on transport fuels in shipping and aviation, a tax on rich nation carbon emissions rights or a fund raised from countries according to their contribution to climate change and ability to pay.