Donald Trump looms like an ominous cloud over this year's United Nations' climate summit that begins Monday in Morocco.
Negotiators have some reasons to be upbeat, even though the UN reported last week that the countries must urgently increase their existing commitments to cut greenhouse gas emissions in order to stave off the most catastrophic impacts of climate change.
The Paris deal officially came into force on Friday – sooner than had originally been expected – as large countries including the United States, China and Canada ratified the climate accord reached in the French capital last December.
In recent weeks, countries concluded separate agreements to reduce emissions in international aviation, which had been left out of the Paris deal, and to dramatically reduce the use of powerful greenhouse gases known as hydrofluorocarbons, which are used in air conditioning and cooling.
In Marrakesh, global environment ministers and climate ambassadors will fashion the rules of the game under which the Paris agreement will operate. Among other things, they must reach agreement on rules for international carbon trading that would allow, for example, Canada to get credit for emission allowances that Ontario and Quebec firms purchase from California in their joint cap-and-trade market.
Heading into the summit, however, there is concern that an election victory by Mr. Trump on Tuesday would stall and even reverse the progress made to date. Democratic Party nominee Hillary Clinton maintains a lead in polls over Mr. Trump but a once-comfortable margin has narrowed considerably in recent weeks and several key battleground states are now considered toss-ups.
The Republican standard-bearer has vowed to rip up the Paris deal, which was ratified in the U.S. by executive order of President Barack Obama who maintained it is not a formal treaty that would require Senate approval. Ms. Clinton, in contrast, has pledged to maintain the American leadership and multilateral efforts established under Mr. Obama.
Mr. Trump – who once claimed climate change is a hoax perpetrated by the Chinese – could withdraw from the Paris accord by executive order in three years and meanwhile let it wither by refusing to meet commitments made by the Obama administration that underpin the deal.
Officials from other countries have expressed their concerns about what a Republican victory would mean for international co-operation on climate change.
China's top negotiator, Xie Zhenhua, criticized Mr. Trump for his stance, saying a "wise political leader" would embrace the international consensus and that failure to do so would hurt American economic and social progress.
In a speech in Ottawa last week, French ambassador Nicolas Chapuis warned about "politicians who live in an age where science is not recognized … We are still at the time of Galileo in that matter."
Asked after the speech what a Trump victory would mean for the climate deal, Mr. Chapuis said: "Everybody is concerned of any movement that could impede what the Paris agreement did. But let's hope that after the eighth of November [election day] these voices just disappear."
Canada's Environment Minister Catherine McKenna was more circumspect, saying she did not want to comment on the possible outcome of the U.S. election. "Clearly, there is an election coming up and parties have different positions, but you work with whoever is sitting across the table from you," Ms. McKenna said. "And that's what we're going to continue to do."
The Liberal minister said Canada will play a leadership role "in bringing countries together around what is the greatest challenge of our generation." She will travel to Marrakesh next week to join the two-week summit.
Among the outstanding issues, negotiators need to reach consensus on how to monitor and verify that countries are indeed achieving the national commitments to reduce emissions. And they will discuss how the Paris agreement can encourage – even require – countries to increase their ambition for GHG reductions.