BONN - UN negotiations on how to implement the climate-rescue Paris Agreement wrap up in Bonn Friday, after two weeks of talks unnerved by an American defence of fossil fuels. President Donald Trump's decision to withdraw the United States from the hard-fought global pact cast a long shadow over talks marked by revived divisions between rich and developing countries.

Key disagreements revolve around how to share out responsibilities for drawing down greenhouse gas emissions, and the money required to do so. Not helping the mood, White House officials hosted a sideline event with energy company bosses Monday to defend the continued use of fossil fuels - coal, oil and natural gas - that emit planet-warming and climate-altering gases when burned.

Unsettled by America's participation at the talks, delegates complained that not enough progress was made in developing a nuts-and-bolts "rulebook" for executing provisions in the Paris Agreement, which enters into force in just three years.

"I have never seen a COP with so little adrenaline," a senior European negotiator told AFP on Friday, using the jargon for the 23rd Conference of Parties (COP 23) to the UN climate convention.

The Paris Agreement, adopted to cheers and champagne in 2015, commits countries to limiting average global warming to under two degrees Celsius (3.6 degrees Fahrenheit) over Industrial Revolution levels, and 1.5 C if possible, to avert worst-case-scenario climate change.

Nations submitted voluntary emissions-cutting commitments to bolster the deal, championed by Trump's predecessor Barack Obama. But scientists say current pledges place the world on course for warming of 3 C or more.

The predicted shortfall has grown by about 0.2 C since Trump's announcement that Washington will abandon the pact, which it cannot legally do until November 2020.

The rulebook, which must be adopted in 2018, will specify how countries count and report on their promised emissions cuts, which need to upgraded in the coming years to bring them in line with the 1.5-2 C target.

"I don't think we've done enough here on the rulebook," said Mohamed Adow of Christian Aid, which represents poor country interests at the talks - citing a lack of "diplomatic leadership" since the departure of the Obama administration.

"We need to have Germany, France, the UK, Canada, New Zealand, and Japan stepping up and providing real leadership that will actually help deliver the ambition of Paris."

Union of Concerned Scientists analyst Alden Meyer said a key dispute was money, with developing countries demanding more certainty and transparency from rich nations on their promise to raise climate finance to $100 billion (85 billion euros) per year by 2020.

Developed nations, he said, "don't want to make three- or four-year projections of what they are going to provide, year by year. But the developing countries have dug in hard on this one."

For their part, donor nations insist on comparable obligations under the Paris pact for developing greenhouse gas polluters, who demand a certain degree of leeway.

"The developing countries are saying: 'If you want us to be accountable on mitigation (of greenhouse gas emissions), you have to be accountable on finance'," said Meyer.

Washington, while waiting to withdraw from the agreement, continues to fill its seat at the climate talks - to the displeasure of many who accuse it of complicating issues in a process it is no longer committed to.

The United States, which under Trump has slashed funding for climate bodies and projects, has taken a tough stance in the finance debate at COP 23.

"The stars are not well aligned since Trump's exit" from the pact, Seyni Nafo, a negotiator for African nations, told AFP of the talks.

"The position of the United States influences other developed countries, which in turn has consequences for the positions major developing nations adopt. It's a game of wait-and-see."

The Trump administration insisted Thursday it was "committed" to limiting greenhouse gas emissions - as long as this does not threaten energy security or the economy.

Acting assistant secretary of state Judith Garber told delegates the US would "support the cleanest, most efficient power generation, regardless of the source" - even as some 20 national governments launched a coal phase-out alliance in Bonn.

The United States is the world's biggest historical greenhouse gas polluter, and second only to China for current-day emissions.