Frontline climate diplomats will seek to translate good intentions into concrete action in Bonn Monday when they gather for the first time since hammering through a historic deal in December.

"Our challenge is now to operationalize the Paris Agreement," France and Morocco -- currently co-chairs of the negotiating process -- said in a briefing note.

After two decades of intense wrangling, the 195-nation Paris accord set ambitious targets to cap global warming and help poor countries cope with its impacts, present and future.

Ratification could happen early next year or sooner, a speed record for an international treaty.

But the landmark deal left a large number of crucial issues unresolved, experts and negotiators say.

"The cooperation shown in Paris will mean nothing if we descend into petty squabbles," Mohamed Adow, a climate expert with Christian Aid, said in a commentary on the Climate Home website.

The most urgent question is how to ramp up national plans for slashing greenhouse gas emissions.

As they stand, these voluntary pledges -- which go into effect in 2020 -- would see Earth's surface heat up by at least three degrees Celsius (5.4 degrees Fahrenheit) compared to the pre-Industrial Era benchmark.

But a climate-fuelled crescendo of superstorms, droughts and rising seas convinced the world's nations to lower the bar to "well below" 2 C, and 1.5 C if possible.

2015 was by far the hottest year on record, and nearly every month in 2016 has also exceeded previous highs.

"History will judge the Paris Agreement... by whether governments, corporations and other actors rapidly increase ambition," the WWF said ahead of the Bonn meeting.

The next "political moment" when countries could deepen their commitments to curb carbon pollution is a so-called "stocktaking" in 2018, a focal point at the talks next week.

- Byzantine process -

Negotiators also have a lot of blanks to fill in when it comes to aid for developing nations which, historically, have contributed least to climate change but are most exposed to its ravages.

"There is pent-up demand for implementation of financial assistance," noted Alden Meyer, a climate analyst at the Washington-based Union of Concerned Scientists who has been tracking the negotiations for 25 years.

"A lot of parties came out of Paris feeling there was more progress on mitigation and decarbonisation" -- measures, in other words, to curb greenhouse gases -- "and less on adaptation".

National plans submitted by poor countries to boost their resilience are contingent on financial aid, but how and when that money will be delivered has yet to be worked out.

"The Earth's oceans are rising, disease is spreading, our land is no longer producing the food we need to survive," said Tosi Mpanu-Mpanu, a climate negotiator from the Democratic Republic of Congo and chairman of the Least Developed Nations group.

The developing world is also concerned that too little of the 100 billion dollars (88 billion euros) per year promised by wealthy nations starting in 2020 will go toward dealing with climate impacts.

"We have just lost five islands in the Pacific," said Amjad Abdullah, chief negotiator from The Maldives and spokesman for the Association of Small Island Nations, referring to several of the Solomon Islands that have now slipped under the waves.

"How much more evidence do we need?"

Negotiators in Bonn also face a mountain of work setting up rules and procedures for carrying out the Paris agreement, especially if it is ratified sooner rather than later.

Even apparently minor issues can block the whole process.

"This stuff has to move as a package," explained Meyer.

The byzantine UN process must likewise become more adept at interfacing with development in the "real world," said Adow.

Major initiatives outside the UN forum include the Solar Alliance, which seeks to inject one trillion dollars over the next 15 years into solar energy, and the Breakthrough Energy Coalition, a club of billionaires promoting renewables, spearheaded by Bill Gates.

The Africa Renewable Energy Initiative -- a five billion dollar, multilateral project -- seeks to boost renewables on the continent, boosting energy supplies and avoiding CO2 emissions at the same time.