Donald Trump’s victory in the US presidential election reverberated around the world this week, not least in the Moroccan city of Marrakesh that is hosting the first major UN talks on global warming since last year’s landmark Paris climate deal was struck.

Mr Trump has vowed to “cancel” the Paris accord and sweep aside many of the commitments to cut fossil fuel emissions that the US had pledged as part of the agreement.

No single country can abolish the Paris deal and it is still too early to know exactly what a Trump presidency will mean for an accord that caps more than 20 years of international negotiations on curbing climate change.

What is clear, however, is that Mr Trump’s election brings to an abrupt halt the excitement surrounding the lead-up to the Marrakesh COP 22 meeting, which had been marked by a rare high point of global co-operation on climate action.

In the space of 11 days in October, governments around the world agreed to take three separate steps to tackle the rise of greenhouse gas emissions, a moment with little parallel in the fraught history of attempts to combat global warming.

First, so many countries rushed to ratify or join the Paris climate accord adopted last December that on October 5 the two thresholds needed for the agreement to enter into force were met: approval by 55 countries accounting for 55 per cent of global emissions. It took more than seven years for the agreement’s predecessor, the 1997 Kyoto protocol climate treaty, to come into effect. The architects of the Paris accord had expected a wait of at least another year.

Then, on October 6, governments struck the first global climate deal for aviation, a fast-growing source of emissions long deemed too hard to include in UN accords such as Paris and Kyoto.

Finally, in the early hours of October 15 in the Rwandan capital of Kigali, another global deal was sealed — to phase out hydrofluorocarbons, or HFCs.

These planet-warming chemicals are used in millions of air conditioners and refrigerators and it is estimated that the Kigali agreement could help avoid as much as 0.5C of future global warming.

It is hard to think of another period when so much international action occurred in such a short time.

Patricia Espinosa, the veteran Mexican diplomat recently appointed the UN’s top climate official, had seen nothing like it before. “I have spent a good part of my career in multilateral affairs and I can tell you it is really unprecedented,” she said, shortly before the US election.

Even before Mr Trump’s victory, large questions remained about whether it would be possible to meet the Paris agreement’s central aim of avoiding dangerous global warming.

Because the Paris agreement came into force sooner that expected, every country ratifying the pact is now legally bound by its terms — including the US for the moment.

That has thrown the spotlight on the climate action plans that countries have volunteered under the accord, known in UN jargon as “nationally determined contributions”.

Countries are not legally obliged to meet any emissions targets in their plans but they do have to update them every five years so that, ultimately, global temperature rises are kept “well below” 2C compared to pre-industrial revolution levels, and 1.5C if possible.

Many decisions still have to be made about the rules guiding exactly what is in these updated plans. The first batch, made ahead of the COP21 meeting in Paris, would still put the world on course for at least 2.9C of warming this century, the UN said last week.

Collectively, these plans amount to a hotchpotch of pledges, from building wind farms to planting trees, with an array of different targets for bringing down emissions.

The US, for instance, has proposed an emissions cut of up to 28 per cent on 2005 levels by 2025, while the EU is planning a 40 per cent cut from 1990 levels by 2030. China has no goal for an outright cut at all, but instead says its emissions will peak by 2030.

The Paris accord stipulates that a new governing body for the agreement should decide “at its first session” on rules for common timeframes in climate plans and other measures making it easier to compare each country’s actions. That includes more common standards for reporting greenhouse gas emissions in a timely and accurate fashion, which is far from the case at present.

The EU, the US and other developed countries have generally submitted emissions data to the UN for at least the year 2013. But some of China’s latest figures date back to 2005 while those of other countries are from the 1990s.

Poorer countries also want to see more transparent reporting of the financing commitments wealthier nations have pledged to deliver to help tackle global warming.

Because the agreement is coming into force unexpectedly early, its new governing body can technically hold its first session in Marrakesh. But dozens of countries have yet to formally ratify the deal, meaning they cannot take part in the early shaping of any decisions.

As a result, it had been expected that the new body would convene and then be suspended, leaving time for more countries to join.

At a minimum, many governments want the Marrakesh meeting to set a deadline of 2018 for agreeing on the “rule book” needed for the Paris accord.

That still makes the meeting important for investors, says Zoe Knight, managing director for climate change at HSBC.

“More clarity on how the aims set out in country plans will be measured and monitored allows a more effective climate risk assessment,” she says.

More than 600 companies have already said they expect to change their strategy as a result of the Paris agreement’s adoption, says Paul Simpson, chief executive of the Carbon Disclosure Project, a non-profit body that compiles company environmental data for hundreds of investors. Some plan to adopt an internal carbon price; others say they will use more renewable energy. But corporations will still be watching closely to see how countries implement the agreement’s rules, as will climate scientists.

Temperatures have already risen nearly 1C since the industrial revolution, following a fossil-fuelled boom in carbon dioxide emissions, and some scientists think the goal of limiting the rise to 2C will be hard to meet, let alone 1.5C.

Average global CO2 levels in the atmosphere reached 400 parts per million in 2015 and surged to new records this year on the back of a powerful El Niño weather system that is likely to make 2016 the warmest year on record.

Experts at Oxford university held a conference in September to consider the Paris agreement’s 1.5C goal. Some attendees had sobering views.

“The very first year at 1.5C could be in about 10 years time if we happen to get an extra warm year on top of the long-term warming trend, like we had with the recent El Niño event,” said Professor Richard Betts, head of climate impacts at the Met Office Hadley Centre in the UK. While it may take more time for temperatures to stick at that level, it illustrates the challenges of meeting the Paris deal’s targets.

The good news is that there has been “remarkable” progress in the growth of renewable energy alternatives to fossil fuels, says Andrew Steer, chief executive of the World Resources Institute research group in the US.

The International Energy Agency recently reported a record-breaking number of installations of wind and solar power last year that has led to renewables overtaking coal to become the world’s largest source of installed power capacity.

“We’ve got a lot to be enthusiastic about,” Mr Steer says. But there is no room for complacency, he adds. “We are still a long, long way off from getting to where we need to get to.”