As well as 147 heads of state, their entourages of 2,000 people and 10,000 delegates from 195 countries, some 14,000 civil society representatives and 3,000 journalists are expected to descend on the Le Bourget conference centre just outside the French capital.
They will all have free passes for public transport and 200 electric cars with drivers will be available to the delegates.
Residents of Paris and the surrounding region have been invited to keep out of their way if they can.
The conference runs from 29 December to 11 December but the busiest days are expected to be Sunday and Monday.
Although public transport is free to all on those days to take pressure off the roads, the authorities have asked people to limit their movements on Sunday and either work from home or take advantage of France's 35-hour working week and take a day off on Monday.
Trains or carriages making an extra 70,000 seats available are in service on those days.
Access is limited to motorways between Paris and the Charles de Gaulle and Orly airports, parts of the Paris ringroad and the road along the banks of the Seine in the west of the city on Sunday and Monday.
Maps of the restrictions can be viewed on the Préfecture de Paris website.
Cop21 in figures:
- 2,800 police officers and gendarmes provide security at the conference centre;
- 6,300 police have been mobilised in Paris, especially around embassies and delegates' hotels, with concern heightened by the 13 November Paris attacks;
- 412,000 meals are to be served throughout the conference;
- 21,000 tonnes of CO2 are expected to be emitted and will be compensated for;
- 170-186 million euros is expected to be the cost of the conference with about 50 companies providing 25 million euros, chiefly by not charging for services;
- 100 million euros are expected to be pumped into the Paris region's economy.