"I understand we now have enough pledges from the international community to meet and exceed the initial Climate Green Fund target of $10 billion," Kerry said during a packed afternoon press conference with former Vice President Al Gore sitting in the front row.

He praised Australia, Belgium, Colombia, and Peru for contributing to the fund this week, adding, "All of this will help to ensure that this fund can succeed in helping the most overburdened nations of the world to do more to be able to respond to climate change."

Kerry then stressed in an impassioned 30-minute speech that the science of climate change is undeniable. He cited punishing weather around the globe, vanishing glaciers, rising sea levels, and record-high global temperatures in 13 of the last 14 years as evidence that the adverse effects of climate change are already upon us.

"Measured against the array of global threats that we face today – and there are many – terrorism, extremism, epidemics, poverty, nuclear proliferation – all challenges that know no borders – climate change absolutely ranks up there equal with all of them," said Kerry, who has attended every UN climate summit since they began 20 years ago.

He added: "I challenge anyone who has thought about the science or listened – actually listened carefully to national security experts tell us that these dangers are real – I challenge them to show us otherwise."