A global climate change agreement went into effect on November 4, putting pressure on nearly 200 countries to start executing plans to slash their greenhouse gas emissions.
"This is a moment to celebrate," said United Nations climate chief Patricia Espinosa. "It is also a moment to look ahead with sober assessment and renewed will over the task ahead."
The Paris Agreement seeks to wean the world economy off fossil fuels in the second half of the century, limiting the rise in average world temperatures to "well below" 2 degrees Celsius above preindustrial times.
It takes effect as the UN projects greenhouse gas emissions by 2030 will exceed by up to 14 billion tons what is needed to keep global warming within that range.
Nearly 200 countries will convene on November 7 in Marrakesh, Morocco, to discuss the far-reaching policy changes, technology, and finance needed to ensure the pact's goals are reached.
"The timetable is pressing because, globally, greenhouse gas emissions which drive climate change and its impacts are not yet falling -- a fact which the Marrakesh meeting must have at the front of its concerns and collective resolve," said Espinosa.