Paris Agreement 2015: What it is and why 1.5C warming matters

In Paris in 2015, nearly 200 countries signed a landmark treaty designed to limit global warming to 1.5C and avoid its worst impacts. Despite progress in areas such as renewable energy, the world has continued to warm at a rapid pace.

A recent UN report stated that the target was likely to be breached in the next few years and that urgent and stringent action would be needed to return the world to 1.5C. The Paris Agreement forms the core of international commitments to tackle rising global temperatures, officially entering into force on 4 November 2016.

However, the United States, the world's second-biggest greenhouse gas emitter, withdrew from the deal in January 2026 under President Donald Trump. The US previously withdrew during Trump's first term before rejoining in 2021 under Joe Biden. The only other UN member states outside the agreement are Iran, Libya, and Yemen.

Stock photo for illustration only, not from the actual event

The Paris Agreement outlines several key commitments, including achieving net-zero greenhouse gas emissions in the second half of this century, requiring each country to set its own emission-reduction targets reviewed every five years, and compelling richer nations to provide climate finance to poorer countries.