The Paris Agreement: 1.5°C Target, How NDCs Work, and the US That Withdrew Twice
Signed by 195 countries in 2015, the Paris Agreement is the world's primary framework for addressing climate change. It set a 1.5°C waght);font-size:1rem;max-width:640px;margin:0 0 8px;"> Signed by 195 countries in 2015, the Paris Agreement is the world's primary framework for addressing climate change. It set a 1.5°C warming limit, requires countries to submit and update emissions pledges, and has no enforcement mechanism. The US joined, left, rejoined, and left again. Here is the full picture and what it means in 2026.
- The Paris Agreement sets a 1.5°C warming limit — global annual temperatures first crossed that threshold in 2024; if all current national pledges are implemented, the trajectory points to ~2.5°C by 2100
- The US has withdrawn twice under Trump (2017 and 2025); Biden rejoined in 2021. The withdrawal process takes one year to complete, limiting diplomatic impact but removing US from formal negotiations
- Country pledges (NDCs) are not legally enforceable — the agreement has no penalty mechanism. Countries set their own targets and update them every 5 years under a voluntary "ratchet" system
- The US is the world's second largest cumulative emitter of greenhouse gases — its absence from the agreement weakens both the political and financial architecture of global climate cooperation
How the Paris Agreement Works
| Element | How It Works | Binding? |
|---|---|---|
| NDCs | Countries set their own emissions reduction targets; submit every 5 years; must increase ambition ("ratchet") | Obligation to submit — not to achieve specific targets |
| Transparency framework | Countries report emissions data and progress on NDCs via biennial transparency reports | Reporting obligations are binding; no enforcement of numbers |
| Climate finance | Developed countries committed $100B/year to developing countries for climate adaptation and mitigation | Politically binding; COP29 (2024) raised target to $300B/year by 2035 |
| Global stocktake | Every 5 years: formal assessment of collective progress toward 1.5/2°C goals | Informational; informs next NDC round |
| Loss & damage | Compensation mechanism for climate harms; formal fund established COP27 (2022) | Voluntary contributions; US withdrawal complicates funding |
Why It Matters for 2026
Trump's second withdrawal — announced January 20, 2025 — follows the same one-year formal process. US participation in UNFCCC negotiations is curtailed. The Biden NDC (50-52% reduction by 2030 from 2005 levels) is abandoned as a federal commitment. US states, cities, and corporations that had pledged Paris-aligned targets continue those commitments independently, but federal climate policy has shifted dramatically away from the Paris framework.
China is now the world's largest annual emitter of greenhouse gases (about 27% of global total). Its NDC commits to peak emissions before 2030 and reach carbon neutrality by 2060. Western analysts debate whether China's renewable energy build-out is outpacing its pledges or whether coal expansion is undermining them. Without both US and China meaningfully reducing emissions, the Paris Agreement's targets are arithmetically unachievable regardless of what other nations do.
The Inflation Reduction Act's $369B in climate and clean energy investments was the US's primary mechanism for meeting its Paris NDC. The Trump administration's efforts to rescind IRA provisions — through reconciliation, executive action, and agency inaction — directly affect whether US emissions decline sufficiently to approach Paris commitments. European trading partners and international investors watch IRA implementation as a proxy for US climate credibility.
Frequently Asked Questions
What is the Paris Agreement 1.5°C target?
The Paris Agreement commits countries to limit global warming to "well below 2°C" and pursue efforts for 1.5°C above pre-industrial levels. The 1.5°C target was added at the insistence of small island nations. The global annual average temperature first crossed 1.5°C above pre-industrial levels in 2024. Scientists note that the Paris target refers to a 20-year running average, not a single year — but the trend is deeply alarming to climate scientists.
What are Nationally Determined Contributions (NDCs)?
NDCs are each country's self-set climate pledges — specific emissions reduction targets by specific years, submitted to the UNFCCC. They must be updated every 5 years and are supposed to increase in ambition over time. Countries are legally required to submit NDCs but not legally required to hit their targets. Current NDCs, if fully implemented, put the world on track for approximately 2.5°C of warming by 2100.
How many times has the US withdrawn from the Paris Agreement?
Twice — both under Trump. The first withdrawal was announced in June 2017 and took effect November 4, 2020. Biden rejoined on January 20, 2021. Trump announced the second withdrawal on January 20, 2025. The formal process takes one year to complete. The repeated US reversals have damaged trust in US climate commitments and complicated long-term international climate finance agreements.
