Fijian Prime Minister Frank Bainimarama has used his first speech as president of the UN climate conference to warn of more suffering without urgent action.
Fiji has launched the UN's climate change conference with a plea for the world to do more to protect its most vulnerable people.
Prime Minister Frank Bainimarama - whose country holds the Conference of Parties (COP23) presidency - said the need for urgency was obvious.
"All over the world vast numbers of people are suffering, bewildered by the forces ranged against them," he told the conference's opening session on Monday in Bonn, citing destructive hurricanes, fires, floods and droughts.
The world must not back away from committing to the more ambitious target outlined in the landmark 2015 Paris agreement on climate action - limiting warming to 1.5 degrees above pre-industrial levels - rather than simply chasing the more widely agreed two-degree target, he said.
"If we don't rise to the challenge, we will definitely fall short and expose our people to more risk, more destruction and more suffering," Mr Bainimarama said.
"This is our moment of truth when all of us in this room will be tested. We must not be found wanting."
The World Meteorological Organisation says the global temperature has already risen 1.1 degrees.
The organisation's Secretary-general Petteri Taalas said the latest science indicated that as things were now, the world was on track to warm by 3-5 degrees - well above the level considered acceptable - and the trend of increasing natural disasters would likely continue until the 2060s.
One of Fiji's key aims for the conference is to establish a Talanoa dialogue - named for the Pacific Islands' spirit of open and constructive debate - to culminate in plans at COP24 in Poland in 2018 for how countries can increase their ambitions to cut emissions.
Fiji's chief negotiator Nazhat Shameem Khan hoped it would result in a roadmap not just for new formal commitments but for an increase in ambition more generally.
"This is a story not just about pre-2020 but ... to see how hard we need to work to make progress," she told reporters.
The head of the UN Framework Convention on Climate Change - the body that underpins the Paris agreement - said the conference had never before met with a greater sense of urgency.
"The message can not get any clearer; we no longer have the luxury of time, we must act now," Patricia Espinosa said.
There has been some concern about America's role after President Donald Trump said in June his administration would pull out of the Paris agreement unless it could secure a better deal.
Ms Khan said the US had continued to engage and support Fiji's presidency and had indicated it intended to remain constructive.
"As to what President Trump actually means for the conditions for either re-engagement or withdrawing, I think this is a domestic matter for President Trump and his voters," she said.
Environment Minister Josh Frydenberg and Ambassador for the Environment Patrick Suckling are leading Australia's delegation to COP23.