Inadequate national targets for curbing climate-altering greenhouse gases meant emissions would be "far above" the level required to stave off disastrous global warming, analysts warned Wednesday.

Instead of the UN-targeted ceiling of two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels, the world was on track for 2.9-3.1 C by 2100, according to the Climate Action Tracker (CAT), a tool developed by a consortium of four research organisations.

"The climate targets so far submitted to the UN by governments collectively lead to global emissions far above the levels needed to hold warming to below 2 C," said a CAT statement.

Fifty-six governments have submitted pledges, known as Intended Nationally Determined Contributions, or INDCs, that will form the backbone of a universal climate-rescue pact to be inked in Paris in December.

Including major emitters China, the United States and the 28-member European Union, pledges so far cover some 65 percent of global emissions, and 43 percent of the world population.

To stay under the 2 C threshold, which scientists say is necessary to avoid catastrophic impacts, greenhouse gas emissions would have to drop from about 50 billion tonnes of CO2 equivalent (GtCO2e) per year today, to 39-43 GtCO2e in 2025 and 36-45 GtCO2e in 2030, according to the CAT.

- Goal 'almost infeasible' -

"The current INDCs lead to emissions levels that exceed the benchmark 2 C limit by 12-15 GtCO2e in 2025, and 17-21 GtCO2e in 2030," said the CAT statement.

Current pledges for 2030 would make the 2 C goal "almost infeasible", it found.

Rather, they would result in temperature increases closer to "2.9-3.1 C by 2100," Bill Hare of Climate Analytics, a CAT contributor, told AFP.

The authors said the current level of ambition should not be locked into the long-awaited Paris agreement -- the first that will commit all the world's nations to slashing CO2 and other planet-harming greenhouse gases.

It was important that the pact include wording on narrowing the gap between what is needed and what has been promised, they warned, as diplomats met in Bonn for the penultimate round of negotiations before the crucial November 30-December 11 Paris conference.

But the negotiators themselves expressed frustration Wednesday at their halting progress, with just seven official negotiating days left before they head for the French capital.

Instead of line-by-line revision of the text, still over 80 pages long and littered with contradictory proposals, the Bonn session had seen "conceptual discussions, going around in circles," Amjad Abdulla of the Maldives, who speaks for the Alliance of Small Island States (AOSIS) told AFP.

"I wonder if there will be any progress to report back at home," added Samuel Adejuwon of Nigeria.

If not, he told a special stock-taking plenary, "it might be difficult for me to justify sending delegates here again in October."

- 'Inadequate' ratings -

Of the 15 INDCs assessed by CAT, seven were rated "inadequate" -- those of Australia, Canada, Japan, New Zealand, Singapore, South Korea and Russia.

Six were rated "medium" -- those of China, the EU, Mexico, Norway, Switzerland and the United States.

Only two, those of Ethiopia and Morocco, were "sufficient" in line with the 2 C goal.

"Most governments that have already submitted an INDC need to review their targets in light of the global goal and, in most cases, will need to strengthen them," said Niklas Hoehne of NewClimate Institute, another CAT contributor.

"Those still working on their targets need to ensure they aim as high as possible."

The ten highest emitters yet to submit INDCs are India, Brazil, Iran, Indonesia, Saudi Arabia, South Africa, Thailand, Turkey, Ukraine, and Pakistan, which together account for 18 percent of global emissions.