World leaders from US President Barack Obama to India's Prime Minister Narendra Modi and Germany's Angela Merkel are to address the gathering. The conference aims to reach a historic deal on tackling climate change.
It is the first time ever that heads of state and government have opened a UN climate conference with speeches. Hopes are high that their statements will send positive signals that a global climate agreement can be achieved in Paris.
Some 150 leaders from around the world are due to speak from 12 noon onwards on Monday with statements to be delivered simultaneously in two meeting rooms, due to the number of leaders attending.
"This is the greatest diplomatic event France has ever hosted," a French diplomat told DW, "and it has been a huge endeavor both in terms of diplomacy and in terms of security."
The French capital is still reeling from the devastating terrorist attacks of November 13, which killed 130 people.
The government has deployed more than 6,000 security officers for the climate conference's opening day.
Observers hope for strong signals
The last time that world leaders personally involved themselves in climate negotiations at the conference in Copenhagen in 2009, it turned out to be a failure. The countries attending agreed merely on an "accord" which did not contain commitments to emission reductions.
Observers agree it was a smart move by the conference's French hosts to invite heads of state and government for the event's opening day rather than involve them in last-hour negotiations.
"Politically speaking, the fact that heads of state and government are here to kick off the conference is extremely important," Jan Kowalzig, a senior climate change advisor with Oxfam told DW.
"We expect these statements to reinforce the political momentum that has been building up towards concluding an agreement," Kowalzig said.
"We also expect that leaders will outline when they expect global greenhouse gas emissions to peak and by when they expect zero greenhouse gas emissions."
Aim: To reach global climate agreement
The task of the two-week-long conference is to come to an accord in which all countries commit to curbing global greenhouse gas emissions in order to prevent the world from warming by more than two degrees by the end of the century, compared to pre-industrial levels.
But while more than 170 countries submitted national reduction pledges ahead of the Paris conference, it is clear that even if all pledges were implemented unconditionally, the world would still warm by around three degrees.
Germany and EU calling for review
"That means that we need a review process to follow up on this issue," said Germany's chancellor Angela Merkel in her weekly video podcast.
"The agreement must be fit for purpose," EU climate commissioner Miguel Arias Canete said in Brussels last week, "and that means that it cannot be static."
Disagreement on finance
The question of whether there should be a global stocktaking of the implementation of pledges and the trend of greenhouse gas emissions, and if so, when such a review should first take place, is one of the issues observers expect to be contentious.
Other issues include financial support to help developing nations embark on a low-carbon growth path and adapt to the impact of climate change, such as rising sea levels.
Pressure to compromise
But on Sunday evening, the French foreign minister put pressure on parties to cut out political maneuvering and demonstrate a willingness to compromise.
At a meeting of negotiators involved in reworking a draft Paris agreement, Foreign Minister Laurent Fabius said he understood that some participants had a tendency to leave others to take the first step. But nobody should wait for any miracles during the conference's final day and night, Fabius added.
"We have to make progress here every day," Fabius said.