The refusal of the United States and Saudi Arabia and Russi to embrace a landmark environmental report has unsettled UN talks to breathe life back into the Paris climate pact, negotiators and observers said.

It may also signal more direct involvement of Donald Trump's White House, they said, in the nitty-gritty of the troubled negotiations, which depend on painstaking consensusbuilding.

A US side event Monday promoting coal, gas and nuclear energy, led by special advisor to the president Preston Wells Griffith, reinforced that impression.

"Alarmism should not silence realism," Griffith said. ”We strongly believe that no country should have to sacrifice economic prosperity or energy security in pursuit of environmental sustainability."

Meanwhile, Carbon Action Tracker (CAT) yesterday reported that average world temperatures are on track to exceed 3.3Cby 2100.

A bloc of 44 small island nations - many facing an existential threat from storm surges engorged by rising seas -called on the UN climate body to "welcome" a UN reporton limitingglobal warming to 1.5C (2.7F) above pre-industrial levels.

Earth's average surface temperature has already risen by about IC.

The motion quickly garnered "an avalanche of support" from more than 100 developed and developing countries, including the European Union, said Rueanna Hayne, a delegate from Saint Kitts and Nevis.

Unveiled in October, the Intergovernmental Panel on Climate Change (IPCC) "special report" concluded that CO2 emissions must drop a quarter within 12 years to stay under 2C, and by nearly half to cap warming at 1.5C, seen as a safer guardrail against catastrophic extreme weather.

The United States disagreed with the motion. Kuwait, Russia and Saudi Arabia voiced similar reservations, and proposed that the UN climate body simply "note" the report, and not "welcome" it.

The issue - unresolved - was shelved.

Reaction at the 12-day talks, scheduled to run through Friday, was fast and furious.

“Saudi Arabia, Russia, Kuwait and especially the United States are rogue nations," said Christian Aid international climate lead Mohamed Adow.

Diplomats also slammed the US position.

"Denial doesn’t change the reality that climate change is already happening and is even worse than we feared," said Hussain Rasheed Hassan, Maldive's environment minister and head of the Alliance of Small Island States (AOSIS).