"Even if all the country commitments from the Paris Agreement are met, the latest data shows that by the end of the century the global climate is likely to be 3C above pre-industrial levels," Bedford said.
"This is substantially higher than the Paris target to limit warming to less than 2C, and would have profound impacts affecting billions of people throughout the world."
"Here in the South Pacific, we are acutely aware of the risks of climate change and sea level rise to our Pacific Island neighbours and we urge all nations to take immediate action on climate change."
Sustainability was one of the main themes to be discussed by leaders at the summit, with a particular focus on the resilience of developing and vulnerable countries to climate change.
"Recognising different capacities, challenges and priorities, the approaches of each nation will not be the same," Bedford said.
"But, they must be informed by the best available scientific evidence, monitoring and evaluation."
The society had produced a trio of recent scientific reports on climate change in New Zealand, focused on broad implications, impacts on health and opportunities for mitigation.
The Government has announced plans for a Zero Carbon Act and an independent, UK-style Climate Commission, both of which aimed to set New Zealand on a path for a net-zero emissions economy by 2050.
Last week, new Parliamentary Commissioner for the Environment Simon Upton said there was no reason a commission couldn't be created.
But it wouldn't be straight forward, and Upton offered nine recommendations for planners to consider.