He said: “While I can’t stand here and speculate about what policies our president-elect, Donald Trump will pursue, I will tell you this. In the time that I have spent in public life, one of the things I have learned is that some issues look a little bit different when you’re actually in office compared to when you’re on the campaign trail.”

Mr Kerry said this when he attended the 22nd session of the Conference of Parties in Marrakech, Morocco.   He added that the truth was that climate change should not be a partisan issue in the first place, for the military, the intelligence community, mayors from New Zealand to Miami, liberal and conservative business leaders alike who are investing unprecedented amounts of money into renewables, voluntarily committing to reduce their own emissions, and even holding their supply chains accountable to their overall carbon footprint.

“There is nothing partisan about climate change for the world scientists who are near unanimous in their conclusion that climate change is real, it is happening, human beings for most parts are causing it, and we will have increasing catastrophic impacts on our way of life if we don’t take the dramatic steps necessary to reduce the carbon footprint of our civilisation.

“Now, whether we are able to meet this moment is a big test – probably as big a test of courage and vision as you’ll ever find.  Every nation has a responsibility to do its part if we are going to pass that test – and only those nations who step up and respond to this threat can legitimately lay claim to a mantle of global leadership.  That’s a fact,” he added.

Mr Kerry said: “We know today what is required, and with all of the real-world evidence, with all of the peer-reviewed science, with all of the plain just old common sense, there isn’t anyone who can credibly argue otherwise. 

“So we have to continue this fight, my friends.  We have to continue to defy expectations.  We have to continue to accelerate the global transition to a clean energy economy.  And we have to continue to hold one another accountable for the choices that our nations make.” “Earlier this year, on Earth Day, I had the great privilege of signing the Paris Agreement on behalf of President Obama and the United States. 

“Let us make clear to the world that we will always remember the stakes.  Let us stand firm in support of the goals that we set in Paris and recommit ourselves to double our efforts to meet them.  Let us say that when it comes to climate change, we will commit not just to doing our best, but as Winston Churchill admonished, ‘we will do what is required’.”

He said: “I look forward to working with you in this important work for whatever number of years ahead I have a chance to.   Mr Kerry said the last time that Morocco hosted the COP was in 2001, and the intervening 15 years have been among the 16 hottest years in recorded history. 

He said 2016 was going to be the warmest year of all.  “Every month so far has broken a record.  And this year will contribute its record-breaking heat to the hottest decade in recorded history, which was, by the way, preceded by the second-hottest decade, which was preceded by the third hottest decade”.“At some point, even the strongest skeptic has to acknowledge that something disturbing is happening.”

He said the world had seen record-breaking droughts everywhere – from India to Brazil to the west coast of the United States, storms that used to happen once every 500 years were becoming relatively normal, “we never saw that in the 20th Century”.

He said communities in island states like Fiji have already been forced to take steps to relocate permanently, because the places they have called home for generations were now uninhabitable, “and there are many, many more who know it’s only a matter of time before rising oceans begin to inundate their cities”