Paris climate agreement: Why does the 1.5C goal matter now?

What the agreement sets out

The Paris Agreement, signed in 2015, is a central part of international efforts to address rising global temperatures. Countries agreed to pursue a limit of 1.5C above pre-industrial levels and keep warming well below 2C.

The deal calls for a balance between human-caused greenhouse gas emissions and the gases removed from the atmosphere, known as net zero, in the second half of this century. Countries set their own emissions targets and review them every five years, with the aim of increasing ambition.

It also calls on richer countries to provide climate finance to help poorer nations adapt and move to renewable energy. The agreement restated a 2009 pledge for richer countries to provide $100bn (£73bn) a year by 2020.

Why every fraction matters

Climate scientists say each additional 0.1C increases risks, including longer heatwaves, stronger storms and wildfires. More extreme weather could also threaten food security in some regions, while climate-sensitive diseases such as dengue may spread more widely.

Some consequences could be irreversible if climate tipping points are crossed. Possible examples include the collapse of the Greenland Ice Sheet, changes to warm Atlantic Ocean currents and further loss of the Amazon rainforest.

Funding and global participation

World leaders meet annually at climate summits known as COPs, or Conferences of the Parties, to discuss their commitments. At COP28 in 2023, countries agreed for the first time to contribute to a transition away from fossil fuels, but no specific action was required.

The final deal at COP30 in 2025 did not directly mention fossil fuels. Brazil, the conference host, instead issued a voluntary roadmap for moving away from them, which is due to be discussed at COP31.