They will attempt to cut greenhouse gas emissions to a level that will limit the global average temperature to a rise "well below" 2C (3.6F) compared to pre-industrial levels - a level of warming deemed to be the point when dangerous climate change could threaten life on Earth.
What is legally binding?Something that is binding within the United Nations framework is 'regular review and submission of emission reduction targets.' But the BBC report goes on:
What won't be legally binding will be the emission targets. These will be determined by nations themselves. Within the agreement the targets are known as Intended National Determined Contributions (INDCs). To date, 187 countries have submitted their INDCs.
Observers have calculated that all of the targets, if delivered, will only curb warming by 2.7C. This is well above, not well below, the 2.0C goal of the Paris Agreement.
This begs the question why the targets themselves are not legally binding under international law. This relates back to the 2009 climate summit in Copenhagen. Observers say the attempt to impose binding targets on countries then was one of the reasons why the talks failed. In Paris, a number of big emitting emerging economies - including China, India and South Africa - were unwilling to sign up to a condition that they felt could hamper their economic growth and development.