Ten Years of the Paris Agreement: The 1.5C Target Is Lost, but Projected Warming Has Fallen from 3.6C to 2.6C

Ten years have passed since the Paris Agreement entered into force. The treaty bound nearly every country to a shared goal: to hold global warming well below 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels and to pursue efforts to limit it to 1.5C (2.7F).

The agreement was adopted by 196 parties at the United Nations climate summit in Paris, known as COP21, on December 12, 2015, and entered into force on November 4, 2016. Today 194 parties — 193 countries and the European Union — belong to the agreement.

Over the decade, the deal has helped drive stronger climate policies and a rapid expansion of clean energy. But emissions remain near record highs, temperatures keep climbing, and countries are still far from the cuts needed to keep a 1.5C limit within reach.

The United States, the world's second-largest greenhouse gas emitter after China, has joined and left the agreement twice. President Donald Trump ordered both withdrawals. The first took effect in November 2020, and President Joe Biden rejoined in February 2021. The US left again in January this year, 12 months after Trump ordered its exit for a second time.

Rather than imposing the same cuts on everyone, the agreement asks each government to set its own targets through nationally determined contributions, or NDCs, outlining how it will cut emissions and adapt to climate change. Countries submit a new, more ambitious NDC every five years, and a Global Stocktake assesses collective progress on the same cycle. The agreement also covers reporting, climate finance and support for developing countries.

The agreement does not force countries to meet their targets. It relies on transparency and international pressure to raise ambition.

Temperatures have kept rising since the deal was adopted. In 2024, the planet was more than 1.5C warmer than preindustrial levels across a full calendar year for the first time.

The past three years, 2023 to 2025, were the hottest on record and the first three-year period to average more than 1.5C of warming. The long-term warming average now stands at about 1.4C, and scientists expect it to surpass 1.5C around the end of this decade.

In October, the UN Environment Programme (UNEP) said the chance of keeping warming to 1.5C without overshooting it has been lost. UNEP Executive Director Inger Andersen said every additional fraction of a degree and additional year of warming above 1.5C increases climate impacts and risks, such as the deadly floods, heatwaves and wildfires that have plagued many nations this year.

Still, the outlook is less bleak than it was in 2015. When the Paris Agreement was signed, existing policies put the world on course for about 3.6C of warming by 2100. According to the Climate Action Tracker, that projection has since fallen to about 2.6C as countries adopted climate policies and clean energy expanded. Progress has stalled since 2021, however, and current policies still point to far more warming than the agreement promised.

Carbon dioxide, the main driver of warming, comes mostly from burning coal, oil and natural gas, while deforestation removes trees that once absorbed it. China, the US and India now produce more than half of the world's annual emissions. China alone emits more than the US, India, Russia and Japan combined, although the US has released the most carbon emissions historically.

Investments in clean energy are now almost double those in fossil fuels, but emission cuts have been too slow to keep 1.5C within reach, and global emissions are 9 percent higher than in 2016. China's emissions have kept rising alongside those of India and Indonesia; Indonesia has climbed into the top 10, replacing Canada. Germany, Japan and the US have cut their emissions, largely by replacing coal with renewables and gas, but growth elsewhere has outweighed those cuts.