If the world wants to solve global warming, fossil fuels will have to stay in the ground, President Obama's climate change envoy Todd Stern said on Monday, reported The Guardian.

Speaking a week ahead of United Nations climate negotiations in Lima, Stern told a forum at the Center for American Progress in Washington, "It is going to have to be a solution that leaves a lot of fossil fuel assets in the ground. We are not going to get rid of fossil fuel overnight but we are not going to solve climate change on the basis of all the fossil fuels that are in the ground are going to have to come out. That's pretty obvious."

With last week's climate deal between the U.S. and China, and with expectations of successful climate negotiations in Paris next year, the message will be clear: fossil fuels are likely to soon be a thing of the past.

Obama and Chinese President Xi Jinping announced last week a combined effort to curb emissions, and a few days later, Obama announced that the U.S. would give $3 billion to an international fund to help poor countries deal with climate issues.

Together, thirty nations pledged money towards the fund. Japan gave $1.5 billion, the United Kingdom, Germany and France each promised around $1 billion, and Sweden pledged more than $500 million, bringing the fund's total to $9.3 billion, just short of the $10 billion goal, according to The Guardian.

"Companies and investors all over are going to be starting at some point to be factoring in what the future is longer range for fossil fuel," Stern said.

When commenting to reporters following his speech, Stern said the recent worldwide efforts helped build momentum in the weeks before the meetings in Lima.

"You are not suddenly going to make the hard issues all vanish," he said. "I don't know whether you are going to see any shift in Lima, for example. We will see what transpires but this is a very big step. Generally if you are holding stock in the Paris negotiations your stock will have gone up after this announcement."