The Paris climate change deal would be a "major leap for mankind", French President François Hollande has said.
Mr Hollande said the world was at a "decisive moment in time" and that global warming beyond the target outlined in the draft deal could have a "very serious impact" on the planet.
He told the conference: "We have to take that last step.
"This will be a major leap for mankind.
"You have to take this opportunity, grasp it, so that our planet may live a long time, that we may live a long time."
The full text of the draft deal will be released on Saturday afternoon before it is agreed on.
UN secretary-general Ban Ki-moon called on nations to have the courage to "grasp" the solutions to climate change in Paris.
With the draft agreement still to be adopted, Mr Ban described it as a "historic document" and a "defining moment in a long journey".
He told the COP21 conference: "The end is in sight. Let us now finish the job. The whole world is watching. Billions of people are relying on your wisdom.
"We must protect the planet that sustains us. For that we need all our hands on deck.
"The solutions to climate change are on the table. They are ours for the taking now. Let us have the courage to grasp them."
A target to keep global temperature rises "well below" 2C above pre-industrial levels and limit the impact to 1.5C was very popular with delegates at the Paris climate conference, according to ITV News science correspondent Alok Jha.
Alok is at the conference and tweeted that reviews of carbon targets were an important part of the agreement.
The "well below" 2ºC and "pursuit" of 1.5ºC targets has made it into next draft (and seem to be very popular in the room) #COP21
A target to keep global temperature rises "well below" 2C above pre-industrial levels and limit the impact to 1.5C has been outlined in the final draft agreement at the Paris climate change conference.
French foreign minister Laurent Fabius said the conference had come up with "an ambitious and balanced agreement" which was "necessary for the entire world".
He said the agreement, if adopted, should make it possible to reduce the risks and impacts linked to climate change.
"If adopted, this text will mark a historic turning point," Mr Fabius told delegates at the conference in the French capital on Saturday.
He said that every five years there would be a "collective stock take" of progress made towards the targets set in the legally-binding agreement.
"The world is holding its breath," Mr Fabius. "It counts on all of us."
French President Francois Hollande will join the Paris climate talks as world leaders are due to be presented with a final draft text of a historic agreement among all countries to fight global warming together.
The deal is expected to include references to making efforts to keep temperature rises to no more than 1.5C above pre-industrial level.
Negotiators at the UN-sponsored climate summit in Paris have reached a draft agreement due to be presented to ministers at 10.30 GMT, according to a French government source.
"There is a draft agreement," the source was quoted by Reuters as saying.
"It is being translated. For it to become a deal, it would have to be adopted."
French foreign minister to announce latest draft text of proposed climate agreement later this morning.Read the full story ›
The environmental schemes discussed on a grand scale in Paris must now work in the real world.
We may all have to make changes to help save the planet from devastating climate change.
Street-level changes will support the big ambitions from Paris, but the problem is human behaviour is as difficult to control as the climate itself.
ITV News Consumer Editor Chris Choi reports:
The world appears to be on the verge of a groundbreaking agreement to tackle climate change, although the final wording is still being argued over at the UN conference in Paris.
The draft text which was published has many agreements in it, but there are still many hard decisions to be made.
ITV News Science Correspondent Alok Jha reports: