Every five years, all 195 signatories of the 2015 Paris Agreement must submit updated plans to reduce their greenhouse gas emissions to limit global warming. These plans, known as Nationally Determined Contributions (NDCs), are key components of the agreement and represent countries’ highest ambitions for emissions reductions over the next decade.
“The NDC is a pledge,” Director of International Government Relations at Woodwell Climate Dr. Matti Goldberg says. “It’s a pledge by a government to reduce their emissions by a certain amount, by a certain time frame. It can also be a pledge of taking certain types of actions. Each NDC also contains plans and measures to put it into action.”
This year, countries must submit their third NDC ahead of COP30 in Belém, Brazil.
How do NDCs fit into the Paris Agreement?
The Paris Agreement is a legally-binding international treaty under the UNFCCC. The treaty states that signatories should work together to limit global temperature increase to “well under 2°C” above pre-industrial levels and pursue efforts to keep the increase below 1.5°C. Nationally Determined Contributions outline how countries plan to achieve this goal and take other measures as part of the global climate effort.
Each NDC must build upon a country’s previous submission and reflect the party’s “highest possible ambition,” according to the Paris Agreement. While parties are legally required to submit an NDC and pursue actions to reach the target, they are “not legally bound to reach the target,” Goldberg says. “It’s a gigantic loophole in a way…although such flexibility is obviously necessary for countries to agree to this, and it does create a structure of pressure.”
After NDCs are submitted, the UNFCCC assesses the combined impact of countries’ NDCs on projected global emissions in a synthesis report. Parties in the Paris agreement also submit a Biennial Transparency Report (BTR) every two years, which outlines each country’s progress made towards accomplishing their NDCs.
“It’s the country’s own assessment,” Goldberg says. “But if a country announces a metric, then others can, of course, also look at whether that metric is being followed. This information creates the basis for civil society and other governments to put pressure on those governments.” Further transparency is created by a process where international experts review each country’s biennial reports.
Despite the ambitious intent of NDCs, Executive Secretary of the United Nations Framework Convention on Climate Change (UNFCCC) Simon Stiell determined last November that previous pledges fell “miles short of what’s needed to stop global heating from crippling every economy and wrecking billions of lives and livelihoods across every country.”
What is in the 2025 NDCs?
NDCs were initially due in February 2025, but with only 13 Parties submitting on time, the UNFCCC Secretariat announced a cut-off date in September to have enough time to prepare its synthesis before the start of COP30 in November. China, the United States, India, the European Union, Russia and Brazil were the world’s top emitters in 2023. Together, these six parties accounted for 62.7% of all global emissions. Of the top greenhouse gas emitters, only the U.S. and Brazil sent in their NDCs as of early September 2025.
The United States submitted its NDC in 2024 under the Biden Administration and set a target of reducing its net greenhouse gas emissions by 61 to 66% below 2005 levels in 2035. After taking office, President Trump issued an executive order announcing the U.S.’s intent to withdraw from the Paris Agreement, which will go into effect in 2026. After January 2026, the U.S. will no longer be required to submit new NDCs or Biennial Transparency Reports.
Despite the country’s withdrawal, Goldberg says the U.S. may see a reduction in greenhouse gas emissions because of its continuing transition from coal to natural gas, renewables and nuclear power — which, according to Goldberg, is driven more by economics and less by policy. Still, Dr. Christopher Schwalm, Vice President of Science at Woodwell Climate, predicts there is “no way” the United States will hit the targets set out in the NDC given the current global political climate. Even if the U.S. does reach its goals, the NDC still does not align with the global 1.5°C limit, according to the Climate Action Tracker. Schwalm calls the 1.5°C target “dead as a doornail.” To reach this goal, we would have needed global greenhouse gas emissions to peak by 2025.
Brazil’s most recent NDC states a goal of reducing greenhouse gas emissions 59% to 67% compared to its 2005 emissions. Goldberg calls it a “pretty ambitious” absolute target for a country classified as a developing country under the UNFCCC. However, the Brazilian climate organization Observatório do Clima states the NDC goals do not align with the global 1.5°C limit.
How could reaching targets in NDCs impact warming trajectories?
Woodwell Climate research scientist Dr. Abigail Lute wanted to see how much of a difference just two of the top-emitting countries’ NDCs could make.
“Are we moving the needle here or not?” she says. “How much are we moving the needle? Are we moving it enough to avoid 2°C? That’s the big picture, to see how ambitious these new pledges are.”
Lute modeled how both the U.S. and Brazil’s promises together could change the global warming trajectory using a “middle-of-the-road” scenario for future greenhouse gas emissions — though, at the moment, that scenario might be more optimistic than our current trajectory, she says.
For the first ten to 20 years after implementing the NDCs, temperatures will temporarily increase. This is due to the reduction in polluting gases such as sulfates that actually have a cooling effect in the atmosphere. After about a decade or two, the reduction in warming gases such as methane and carbon dioxide will cause temperatures to fall.
According to Lute’s calculations, under moderate emissions scenarios, the probability of exceeding 2°C is 25% by 2050 and 78% by 2100. If both the U.S. and Brazil reach their NDC targets, the probability of exceeding 2°C stays about the same for 2050 but drops down to 73% for 2100.
Global warming is expected to reach 1.8°C by 2050 and 2.3°C by 2100 under the medium emissions scenario. With the U.S. and Brazil’s combined NDCs, Lute expects warming to be reduced by about 0.01°C in 2050 and 0.06°C by 2100.
While these contributions may seem small, Brazil and the U.S. only represent two of the 195 parties in the Paris Agreement.
“It’s two of the larger ones for sure, but it’s only two,” Lute says. “If we extrapolate it to everybody, then it can make a meaningful difference…the story here is that everybody needs to contribute. This is a collective problem, and even one large country can’t solve it.”
One of President Trump’s first actions this past week—and also in his first term—was to announce the withdrawal of the United States from the Paris Agreement. It is a step that is both misinformed and misguided. But how much difference will it make? Here’s what you need to know.
1. Significance of the Paris Agreement
The Paris Agreement was adopted by 197 countries in December 2015 and has been the underpinning of international climate action for nearly a decade. The goals and strategies it sets out are critically important to maintaining a stable climate, which is the foundation of successful societies and economies. The Parties to the Paris Agreement are legally obliged to submit national climate plans, known as Nationally Determined Contributions (NDCs) every five years. However, the content and level of ambition of those NDCs are (as the framing “nationally determined” makes clear) up to the Party itself.
2. Immediate legal implications
The Paris Agreement stipulates that any nation’s withdrawal takes effect one year after an official notice has been submitted to the Secretary-General of the United Nations. In the case of the United States, the earliest effective date of official withdrawal is, therefore, sometime in January 2026. After that, the country will not be bound by its obligations under the Paris Agreement. Those include the submission of NDCs every five years, accounting of progress toward commitments, the submission of biennial transparency reports, and the general obligation to provide climate finance. The United States will also lose, in particular, its right to vote on decisions within the governing body of the Paris Agreement, to nominate members to institutions serving the Paris Agreement, and to participate in emission trading under the Paris Agreement. However, as the United States submitted a new NDC and a biennial transparency report in December 2024, it is currently in compliance with the key obligations under the Paris Agreement.
3. What withdrawal from the Paris Agreement doesn’t do
The executive order of January 21, 2025 does not withdraw the US from the UN Framework Convention on Climate Change (UNFCCC), the 1992 treaty that established the international climate negotiation process. The language of the executive order indicates that this is deliberate—the US will retain its right to vote in the Conference of Parties, as well as its reporting obligations under the UNFCCC. This is possibly due to the fact that a withdrawal from the UNFCCC, a treaty ratified by the U.S. Senate in 1992, requires a two-thirds majority in the Senate. It is also notable that no action has been taken to withdraw the NDC submitted by the Biden Administration in December 2024.
4. The policy impact
The United States’ withdrawal makes maintaining—let alone enhancing—the ambition of emission reduction efforts across the world significantly more difficult. When a major emitter “free-rides,” it de-motivates ambition by others. However, although the U.S. has the second-highest GHG emissions in the world, and has always been a key player in global climate collaboration, it is important to bear in mind that 194 other countries representing approximately 90% of global emissions have not withdrawn from the Paris Agreement.
The executive order is targeted at stopping any U.S. climate finance contributions. This will mean that the new global climate finance goal of $1.3 trillion per year by 2030, agreed upon in Baku, has become much harder to achieve. This will impact the poorest countries directly, as well as degrading the international community’s trust in the effectiveness of the process.
5. What happened last time
President Trump also withdrew the U.S. from the Paris Agreement during his first administration. Then, as now, one of the primary impacts was to create a leadership vacuum. In that case, that vacuum was largely filled by other nations, plus state, local, and business leaders. The resulting groundswell generated momentum that carried into the Biden Administration and the U.S. re-entry into the Paris Agreement. While much of that foundation remains strong, trends in the private sector have shifted, with a growing number of major corporations and financial institutions backing away from their climate commitments. Global geopolitics has also evolved, raising questions about what role other governments, in particular China, might play in reaction to the United States’ withdrawal from the international governance structures.
