About 40,000 negotiators from nearly 200 countries are descending on the French capital for the UN conference on climate change or COP 21.
The decisions they make will have a major impact on how we live our lives and those of future generations.
Scientists have warned that if greenhouse gas emissions continue to rise, we will pass the threshold after which climate change will become catastrophic and irreversible.
That threshold is two degrees Celcius above pre-industrial levels, and scientists say a rise in global temperatures must not exceed that figure by the year 2100.
But delegates face a number of problems. Although many countries have already made pledges to reduce their greenhouse gas emissions in the run up to COP 21, it is likely they will not be enough to slow global warming to two degrees.
The second problem relates to the differences between developed and developing countries. Developing nations want financial aid to help them implement the policies that will be a part of any Paris deal.
So, with so much at stake, can leaders reach an agreement in Paris?
Presenter: Hazem Sika
Tim Forsyth - Professor of environment and development at the London School of Economics and Political Science
Samantha Smith - Head of the World Wildlife Fund's global climate and energy initiative
Rasmus Valanko - Climate policy specialist and manager of climate and energy at the World Business Council for Sustainable Development
Source: Al Jazeera