Under the Paris Agreement, 195 nations vowed to hold average global warming to well under two degrees Celsius (3.6 degrees Fahrenheit), and even 1.5 C if possible (AFP Photo/Janek Skarzynski)

Bonn (AFP) - Even after the world sealed a historic climate deal in Paris, the UN's climate chief is worried humanity won't be able break its fossil fuel habit in time to avert catastrophe, she told AFP Thursday...

"My concern is whether the transformation is going to happen fast enough to avert the worst impacts," Christiana Figueres said, referring to the global shift from carbon-polluting fossil fuels to green energy.

"Greenhouse gas emissions have to peak quickly and descend," she said in an interview, as diplomats wrapped up their first negotiating session since hammering out the landmark pact in December.

"It is a race against the clock."

Figueres, from Costa Rica, took on the UN climate brief in the aftermath of the failed 2009 Copenhagen summit, and played a key role in laying the groundwork for the world's first universal climate deal.

Under the Paris Agreement, 195 nations vowed to hold average global warming to well under two degrees Celsius (3.6 degrees Fahrenheit), and even 1.5 C if possible.

Barely 1 C of warming so far has fuelled a crescendo of devastating droughts, super storms and rising seas threatening the homes and livelihoods of tens of millions.

But the tally of national pledges to curb greenhouse gases still falls far short of the mark, and scientists say they must be rapidly strengthened to hit the Paris goal.

Wealthy nations have also agreed to funnel trillions of dollars to poor countries in the coming decades to help them cope with climate impacts, and retool their economies.

Frontline negotiators tasked with converting the political blueprint into a workable plan met in Bonn for the 10-day session, and will reconvene along side their ministers in November in Marrakesh, Morocco.

Stepping down in July, Figueres was feted by the climate diplomats in a joint work session.

During the emotional send off, she was even regaled in song to the tune of a 1970s Abba hit as a "Climate Queen".

Famously -- some would say stubbornly -- upbeat, Figures told AFP that her six-year mandate was also filled with harrowing, make-or-break moments.

"I made a deliberate decision to be optimistic early on," she explained.

"It was in response to the situation that I inherited, which was anything but optimistic."

- Moments of crisis -

After the Copenhagen debacle, it was an open question whether the UN could get climate talks back on track.

Each of the six end-of-year climate meets she oversaw was laced with "moments of crisis," Figueres said.

During the 2011 summit in Durban, South Africa, where the 2015 Paris deadline was set, the press was reporting that the negotiations -- deep into overtime -- had failed, she recalled.

"That's when you have to take a deep breath," she said.

The December deal has ushered in a new spirit of cooperation between rich and developing nations that was often absent during more than 20 years of fraught talks, she added.

"There is much more willingness to address this problem collectively," she said, echoing the view of many diplomats and observers here.

But the Paris pact is only a framework and still needs to be fleshed out.

"It's like moving into a very large, unfurnished house" with 196 flatmates, Figueres said. "And all the decisions have to be made by consensus."

Figueres will be succeeded as Executive Secretary of the UN Framework on Climate Change by former Mexican minister Patricia Espinosa, currently ambassador to Germany.

To help do something about the climate change and global warming emergency, click here.

Sign up for our free Global Warming Blog by clicking here. (In your email, you will receive critical news, research, and the warning signs for the next global warming disaster.)

To share this blog post: Go to the Share button to the left below.