Kerry takes granddaughter to UN climate deal signing

US Secretary of State John Kerry brought his granddaughter to work Friday as he joined senior world officials to formally sign the Paris climate deal at the United Nations.

Washington's top diplomat came to the podium cradling two-year-old Isabelle Dobbs-Higginson and triggered warm applause as he endorsed the accord for the United States.

Earlier, Kerry had addressed the General Assembly to hail the agreement, which he said was the last chance to slow the devastating pace of human-generated climate change.

"We learned that 2015 was the hottest year in recorded history - by far," Kerry said, recalling last December's Paris summit where the agreement was finalized.

"And we learned that after knowing that the past decade was the hottest on record, and the one before that was the hottest on record," he continued.

"And now we know that this year is already on track to be the warmest of all, and last month, March, was the hottest recorded March in all of history.

"This past winter, the maximum extent of Arctic sea ice was the lowest ever reported - breaking the record that was set just one year ago.

"So the urgency of this challenge is only becoming more pronounced," he said, in a warning to those building the world his granddaughter will grow up in.

Isabelle is the daughter of Kerry's eldest daughter, filmmaker Alexandra Kerry.