Ri was the 76th representative to sign the "Paris Agreement," which was adopted in December to replace the Kyoto Protocol on climate change. After the signing at the podium of the U.N. General Assembly Hall, each participant shook hands with Ban.
A smiling Ban welcomed Ri as he took steps to leave the podium after the signing, and the two shook hands.
During the hand-shaking, Ban held Ri's right hand with both hands, while Ri put his left hand on the right arm of Ban in apparent gestures of affinity. While shaking hands, they talked to each other for some 13-14 seconds before posing for cameras.
Each delegate made a three-minute speech on climate change, and Ri used the opportunity to criticize the U.S., arguing that social and political stability must be guaranteed in order to address global environmental problems, but what he calls U.S. nuclear war exercises are destabilizing the situation.
Ri arrived in New York on Wednesday for a four-day trip.
The visit has drawn keen media attention as it marks Ri's first since tensions spiked following the North's fourth nuclear test in January, its long-range rocket launch in February and the adoption of a new U.N. sanctions resolution last month.
Ri last visited New York in September to attend the U.N. General Assembly.
Speculation had arisen that the trip could provide opportunities for Ri to hold talks with U.S. officials, such as Secretary of State John Kerry amid growing concern that the North could conduct yet another nuclear test. But the State Department said Kerry has no plan to meet with Ri.
Ri is not expected to hold a formal meeting with Ban either. An official of the North's mission to the U.N. said the North has not asked for a meeting with the U.N. chief. (Yonhap)