The Latest on the U.N. signing ceremony for the climate change agreement (all times local):

9:20 a.m.

U.N. Secretary-General Ban Ki-moon says at the start of a high-level U.N. ceremony where a record 171 countries are expected to sign the landmark climate change agreement that "history is in the making."

The U.N. chief told global leaders and ministers on Friday that the world is in "a race against time," citing record global temperatures, record ice loss and record carbon levels in the atmosphere.

"The era of consumption without consequences is over," Ban said. "We must intensify efforts to decarbonize our economies."

Ban, who recalled that climate change has been his top priority since he became secretary-general over nine years ago, urged all countries to ratify the agreement so it can come into force as early as possible.

The agreement will enter into force once 55 countries representing at least 55 percent of global emissions have formally joined it.

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00:02 a.m.

Up to 170 countries are expected to sign the Paris Agreement on climate change Friday as the landmark deal moves closer to entering into force years ahead of schedule.

Secretary of State John Kerry is joining dozens of world leaders for a U.N. ceremony that should set a record for international diplomacy: Never have so many countries signed an agreement on the first available day.

States that don't sign Friday have a year to do so.

Many expect the climate agreement to enter into force long before the original deadline of 2020. Some say it could happen this year.

After signing, countries must formally approve the agreement through their domestic procedures. The United Nations says at least 13 countries could take that step Friday by depositing their instruments of ratification.