The most significant international agreement designed to reduce greenhouse gas emissions is the Paris Agreement, adopted in 2015 by 195 nations. But it wasn’t the first attempt. The global effort to tackle climate change has produced a series of treaties spanning more than three decades, each building on the last, starting with a broad framework in 1992 and gradually adding specific targets, timelines, and financial commitments.
The 1992 Framework That Started It All
The United Nations Framework Convention on Climate Change (UNFCCC), adopted in New York on May 9, 1992, was the first major international treaty focused on climate change. Its ultimate aim: preventing “dangerous” human interference with the climate system. The treaty called for stabilizing greenhouse gas concentrations at a level that would allow ecosystems to adapt naturally, protect food production, and let economic development continue sustainably.
The UNFCCC didn’t set binding emission limits for individual countries. Instead, it created the institutional scaffolding for future negotiations, establishing annual meetings (called “Conferences of the Parties,” or COPs) where nations would hammer out more specific commitments. Nearly every country on Earth eventually joined, making it the foundation for every climate agreement that followed.
The Kyoto Protocol: First Binding Targets
The Kyoto Protocol, agreed in 1997, was the first treaty to impose legally binding emission reduction targets on developed nations. During its first commitment period (2008 to 2012), 37 industrialized countries and the European Community committed to cutting greenhouse gas emissions by an average of 5 percent compared to 1990 levels.
This was a meaningful step, but it had a major structural limitation. Only wealthy, industrialized nations were required to cut emissions. Large developing economies like China and India had no binding targets. The United States signed the protocol but never ratified it, meaning it never took effect domestically. Canada later withdrew entirely. These gaps meant the treaty covered only a fraction of global emissions, and its impact on the overall trajectory of greenhouse gases was modest.
The Paris Agreement: A Global Commitment
The Paris Agreement, adopted on December 12, 2015, at COP21 in Paris, represented a fundamentally different approach. Rather than imposing top-down targets on a handful of countries, it asked every nation to set its own emission reduction goals. Its overarching target: hold the increase in global average temperature to well below 2°C above pre-industrial levels, while pursuing efforts to limit warming to 1.5°C.
Participation is nearly universal. As of now, 194 out of 198 parties to the UNFCCC have ratified the agreement. That breadth of commitment is unprecedented in climate diplomacy.
The mechanism that drives the Paris Agreement is called “nationally determined contributions,” or NDCs. Each country submits a plan outlining how it intends to reduce emissions and adapt to climate impacts. These plans are updated every five years, and each new submission is expected to be more ambitious than the last. This built-in escalation, sometimes called the “ratchet mechanism,” is designed to close the gap between current policies and what the science demands over time.
The Paris Agreement is a legally binding treaty, but the individual emission targets each country sets are voluntary. No country faces penalties for missing its goals. The enforcement mechanism is essentially transparency and peer pressure: nations report their progress, and the global community can see who is falling short.
The First Global Stocktake
In 2023, at COP28, the world completed its first “global stocktake,” a comprehensive assessment of how well nations are doing under the Paris Agreement. The results were sobering. Progress was too slow across every area of climate action, from cutting emissions to building resilience to financing vulnerable nations.
The stocktake confirmed that global greenhouse gas emissions need to fall 43 percent by 2030 (compared to 2019 levels) to keep the 1.5°C target within reach. Countries are currently off track to meet that benchmark. In response, nearly 200 parties agreed to accelerate action before the end of the decade, including a historic call to transition away from fossil fuels.
Climate Finance Commitments
Money has been one of the most contentious parts of climate negotiations. At the Copenhagen summit in 2009, developed countries pledged to mobilize $100 billion per year by 2020 to help developing nations address climate change. That goal was later extended through 2025 as part of the Paris Agreement.
Developed nations missed the 2020 deadline. According to OECD tracking, they finally hit the target in 2022, providing and mobilizing $115.9 billion in climate finance for developing countries. That was two years late, though one year earlier than some projections had anticipated. Looking ahead, negotiations are underway for a new, larger climate finance goal to take effect after 2025.
Other Agreements With Greenhouse Gas Impact
The Montreal Protocol, originally designed in 1987 to protect the ozone layer, has had a surprisingly large effect on greenhouse gas emissions. Many of the chemicals it phased out were also potent heat-trapping gases. Its 2016 Kigali Amendment went further, targeting hydrofluorocarbons (HFCs), chemicals widely used in air conditioning and refrigeration that don’t harm the ozone layer but are extremely powerful greenhouse gases. The Kigali Amendment’s phase-down schedule is expected to avoid more than 80 billion metric tons of carbon dioxide equivalent emissions by 2050, preventing up to 0.5°C of warming by the end of the century.
This makes the Montreal Protocol, a treaty most people associate with the ozone hole, one of the most effective climate agreements ever enacted, in part because its phase-down schedules are mandatory and include trade restrictions that discourage non-compliance.
How These Agreements Fit Together
The international effort to reduce greenhouse gas emissions isn’t a single agreement but a layered system. The 1992 UNFCCC provides the legal and institutional framework. The Kyoto Protocol was the first attempt at binding targets but applied only to industrialized nations. The Paris Agreement brought every country into the fold with voluntary, escalating commitments. The Montreal Protocol and its Kigali Amendment tackle specific industrial chemicals with binding phase-down schedules.
Each agreement reflects lessons learned from the one before it. Kyoto showed that excluding major emitters undermines effectiveness. The Paris Agreement traded binding national targets for universal participation, betting that transparency and regular updates would drive ambition upward over time. Whether that bet pays off depends largely on what happens in the next five-year NDC cycles, with the next round of updated national plans due in 2025.