Governance & Policy

Ratchet Mechanism

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Definition

The ratchet mechanism is the Paris Agreement's cyclical design for increasing ambition over time: parties must communicate a nationally determined contribution every five years, each successive NDC required to be a progression beyond the current one and to reflect the party's highest possible ambition. Informed by the global stocktake, the cycle is intended to "ratchet up" collective ambition toward the agreement's temperature goals.

References

unfccc.intBulk import source

Source imported for editorial provenance.

UNFCCCGlobal Stocktake (Article 14 basis; three phases; first GST concluded at COP28 in 2023, every five years thereafter; modalities in Decision 19/CMA.1)

This reference provides supporting context for how “Ratchet Mechanism” is defined and used.

Overview

How it is used

The mechanism structures the entire UNFCCC calendar — NDC cycles (2020, 2025, 2030...) , global stocktakes (first concluded 2023), and ambition discussions at each COP.

Why it matters

The ratchet is the Paris Agreement's engine: the bet that transparency, repetition and peer pressure can drive ambition upward faster than top-down allocation ever did.