The Paris Agreement
The Paris Agreement was implemented as a collaborative global response to climate change, with a goal of reducing emissions. It aims to keep the global temperature rise to just 1.5°C, which would significantly reduce the risks and the impacts associated with climate change. President Donald Trump later decided to pull the US out of the agreement, describing the move as "a reassertion of America’s sovereignty".
While a dwindling band of refuseniks still insist that it doesn't exist, climate change is already here, and it's only going to get worse, with some of the severe effects having already started to take hold.