Mr Sharma, the summit president, apologised on Saturday for how the deal negotiations concluded with last-minute changes on the wording about coal.
The visibly emotional Mr Sharma said he was “deeply sorry” for the way last-minute negotiations had unfolded, after India and China forced a change to the text of the deal agreed in Glasgow on Saturday to water down language on the phaseout of coal power.
Addressing delegates, he said: “May I just say to all delegates I apologise for the way this process has unfolded and I am deeply sorry.”
The former business secretary told the BBC’s Andrew Marr Show: “In terms of what happened yesterday, we managed to get an enormous amount over the line.
“On a personal level, I have invested enormous amounts of the last two years into this.
“I’ve been out to see countries, talked to people on the front line of climate change, and of course I’d had about six hours sleep in 72 hours previously, so it was an emotional moment.”
Mr Sharma said it had been his job to “build consensus” on the final deal, as he denied the Glasgow Pact had ended in failure.
Asked whether his emotional reaction to the change in language on coal was an admission of failure, Mr Sharma replied: “I wouldn’t describe what we did yesterday as a failure - it is a historic achievement.”
In an interview with Sky News’ Trevor Phillips On Sunday programme, he also argued that China and India would have to “justify” their actions to “climate vulnerable” countries.
He said: “On the issue of coal, I should point out that for the very first time in any of these conferences, the word ‘coal’ is actually reflected in the text. That again is a first.
“Yes, of course I would have liked to ensure we maintain the ‘phase out’ rather than changing the wording to ‘phase down’, but on the way to phasing out, you’ve got to phase down.
“But, ultimately, of course, what we need to ensure is that we continue to work on this deal, on these commitments, and on the issue of coal, China and India are going to have to justify to some of the most climate vulnerable countries what happened.
“You heard some of that disappointment on the floor (of the conference).
“What I would say to you is that overall this is a historic agreement, we can be really proud of it but, of course, this is just the start – we now need to deliver on the commitments.”