"To keep poor counties from siding with China, India etal on issues like transparency, you might offer them this deal: whatever commitments they make are contingent on the availability of an option that is good for their economics," Bill wrote in an email to Hillary on December 17, 2009.
Hillary and US President Barack Obama were camping in Copenhagen to arrive at a deal, which was being opposed by countries led by China and India, which tried to rally behind them the Third World countries.
"I recommend that you begin by saying that this challenge is an opportunity if we approach it the right and way and provide the right financing options so that the old energy economy no longer has an advantage over new ways of providing and consuming energy," Bill said.
From the content of the email it looks like Hillary had sought advice from her husband on the best way forward to address the challenge of climate change at the summit.
"Hillary, I've had a busy day and too little time to study all the articles enough to give much good advice," Bill Clinton wrote in the email, which was released by the State Department on Friday.
These documents were provided to the State Department by the FBI and were reviewed using Freedom of Information Act (FOIA) standards for public release.
These are 75 documents totalling 273 additional pages of emails sent or received by Hillary in her official capacity during her tenure as Secretary of State.
"In relation to the 75 documents we are releasing today, more than half are 'near duplicates' of documents previously provided by former Secretary Clinton and released in previous FOIA productions of her emails," State Department Spokesman John Kirby said in a statement
"For instance, a 'near duplicate' would be substantively identical to previously released emails but for a top email in the chain stating 'please print'," Kirby said.
In his op-ed in USA Today, which was attached in the email, Bill wrote that China has embraced the potential of clean-energy technologies, because they see the potential of an enormous global market.
"India also has committed to reducing its emissions by up to 25 percent by 2020 and is aggressively pursuing a wide range of new opportunities. Here in the United States, the President and Congress are beginning to tap our clean-energy potential to create millions of sustainable, good-paying jobs," he said.