Hey, I'm really struggling with this question, can you please help me out?

Emissions reduction treaties between nations have been proposed as a key method with which to tackle climate change and its negative impacts. One such treaty is the Paris Agreement. Adopted by 197 nations in 2015, the deal aims to substantially reduce carbon emissions and to limit the global temperature increase in this century to 2 degrees Celsius.

Why are binding treaties to abate emissions between groups of nations are often difficult to achieve?