Under the Paris Agreement, adopted at COP21 in 2015 with an entry into force the following year, countries set a global goal to keep global warming well below 2°C and pursue efforts to limit it to 1.5°C. Ten years on, as countries grapple with competing priorities, including cost-of-living pressures, one question stands out: has the Paris Agreement made a difference?

That turns out to be a difficult question to answer. The Kyoto Protocol, the Paris Agreement’s predecessor, set binding targets for some countries only. This created a point of comparison, much like a control group in a medical trial, and allowed researchers to assess whether countries subject to targets reduced emissions differently from those that were not. The Paris Agreement works differently: nearly all countries set their emission goals through Nationally Determined Contributions (NDCs) and, without a clear comparison group, evaluating its effect is less straightforward. 

To address this challenge, the OECD carried out a study, using two complementary approaches to gain insights on the effect of this global agreement: first, by examining how emissions trends changed after 2015; and second, through a survey of climate policy experts on their perception of the difference the Paris Agreement has made.

The OECD examined emission, economic and energy data from 170 countries since 1990, comparing trends before and since 2015. Meeting the Paris goals means emissions need to peak and start falling, but the data show that global emissions are still rising, albeit more slowly after 2015 (Figure 1). From the mid-2000s to 2015, global emissions were growing by about 1.8% a year. That growth slowed to 0.7% a year after 2015.

Two developments are driving the slowdown: a cleaner energy mix and slower economic growth. Not only has the share of energy from low-carbon sources increased, but fossil fuels are being used more efficiently. The shift from oil to natural gas has also contributed to limiting emission growth. At the same time, the global economy grew more slowly after 2015, which contributed to slowing down emissions growth. In the absence of further decoupling, a possible future increase in the global GDP growth rate may put upward pressure on emissions.

Encouragingly, the OECD analysis shows that economic growth and slower emission growth can go hand in hand. The overwhelming majority of the 90 countries that improved emissions trends after 2015 continued to grow their economies. In 40 countries, emissions declined even as GDP continued to increase. Remarkably, countries such as France, the Netherlands and New Zealand achieved more substantial emission reductions while also recording stronger economic growth than before.

Source: Adapted from OECD (2026) Emissions Unpacked: trends and drivers before and after 2015

Emissions trends can only tell part of the story. To better understand the Paris Agreement’s effect, the OECD also surveyed over 250 climate policymakers and experts across more than 60 countries and asked them directly. 

Across the board, experts gave a consistent answer: the Paris Agreement has been perceived to have made a meaningful difference (Figure 2).

Most experts agreed that, without it, climate change would likely rank lower on political agendas, climate policies would be less developed, and international efforts would be more fragmented and less effective. This holds both for the past 10 years and looking ahead. In other words, experts thought that the Paris Agreement helped make climate action more common, more visible and more co-ordinated.

The responses also highlight the effect of the Paris Agreement’s novel approach on international co-operation. Not only did it raise countries’ ambition, with more ambitious targets than they otherwise would have set, but it also enabled broader participation, with climate action becoming an expectation in most countries. Finally, it led to greater accountability thanks to its five-year review cycle.

Source: OECD survey on the transformative effect of the Paris Agreement, 2025

Ten years on, the two OECD studies together suggest that the Paris Agreement helped increase climate action and that the growth of emissions has slowed. Keeping warming well below 2°C, however, will require a much faster transition, with global emissions peaking and entering sustained decline.

Both analyses point to a similar set of factors to further reduce emissions: accelerating the transition to a cleaner energy mix, faster electrification in transport, buildings and industry, and accelerating energy efficiency improvements.

Experts also flagged the persistence of barriers and the importance of political commitment, public support and sustained public and private investment. 

Looking ahead, the challenge is implementation. The question is not only whether countries are willing to make commitments, but also whether they can translate commitments into action and measurable progress. COP31, which opens five days after the tenth anniversary of the Agreement’s entry into force, is expected to reflect this shift in focus. An early signal is the COP31 Presidency’s proposed global electrification target, which aims to increase electricity’s share of final energy demand from just over 20% today to 35% by 2035. By shifting transport, buildings and industry to cleaner and more energy-efficient electric technologies, electrification brings together the key drivers of emission reductions identified in both the data analysis and the expert survey.