The ASEAN-UN Summit is on partnership for sustainability and "the most dramatic threat to sustainability today is climate change," said Guterres, adding that it is a major concern for all.

"Climate change is running faster than we are, and we all see the impact of climate change in natural disasters."

He said that the sea level is rising much faster than expected and new research forecast that 300 million people will be flooded by sea water in 2050 if climate change can not be contained.

The UN chief pointed out that efforts were needed to limit the temperature increase to 1.5 degrees Celsius above pre-industrial levels by the end of the century and to reduce CO2 emissions by 45 percent in the next decade. "If we miss these objectives, the situation will be catastrophic."

During the summit, UN and ASEAN states also discussed topics including disaster risk reduction, counter-terrorism, ASEAN Community Vision 2025 and the UN 2030 Agenda for Sustainable Development, the UN chief said.

Founded in 1967, ASEAN groups Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam. Thailand, the rotating chair of ASEAN for 2019, is holding the 35th ASEAN Summit and the related summits on Nov. 2-4.

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