An imminent scientific summary on climate change will serve as an "alarm clock moment" for the world, AFP reports citing the UN climate chief.
The eagerly awaited UN report, whose summary will be released Friday in Stockholm, is expected to stress the escalating threat from climate change.
"This report constitutes an alarm clock moment for the world," said Christiana Figueres, executive secretary of the UN Framework Convention on Climate Change.
"It will tell us again that everything that we thought we knew on climate change has actually been underestimated," she told reporters at the UN General Assembly.
A draft of the summary seen by AFP declares with the greatest emphasis to date that climate change is on the march and humans are responsible for it.
"The question, of course, is what governments do to address this," Figueres said.
UN-led international talks have set a goal of checking global warming at no more than 2.0 degrees Celsius (3.6 Fahrenheit) above pre-industrial levels.
"It is clear that all the actions, all the pledges that we have now are not going to be enough to reach" the goal, Figueres said.
UN Secretary General Ban Ki-moon has called for a summit on climate change at the world body in September 2014.
The summit would come one year ahead of talks in Paris that are designed to seal a new international treaty on climate change.