The Paris Agreement is an historic turning point in the global climate change battle. There is broad consensus it contains the necessary ingredients to put the world on a path towards a zero-carbon, resilient, prosperous and fair future.

However, to fully understand why the Paris Agreement is such an achievement, we must unpack one of its core ingredients, what has become known as the ambition mechanism or cycles of action. This mechanism lays out a process to continue strengthening action in a regular and timely way every five years, starting before 2020.

This mechanism is what makes the Paris Agreement a dynamic and long-lasting accord that will be responsive to the science of climate change, shifts in technology and economic opportunities, and to growing public support for action.

What Is an Ambition Mechanism?

For the first time in the history of global climate policy, the Paris Agreement establishes an ongoing, regular process to increase action by all countries. To understand this ambition mechanism, it is necessary to break it down into its core components:

  1. Global Stocktake of implementation and collective progress every five years;
  2. Submission of updated nationally determined contributions (NDCs) from each country every five years informed by the Global Stocktake; and
  3. Expectation of progression and highest possible ambition for each successive contribution.

This process of review and revision every five years provides the means through which the Paris Agreement’s goal—to keep temperature rise to well below 2 degrees C (3.6 degrees F) and pursue efforts to limit temperature increase to 1.5 degrees C (2.7 degrees F)—can be achieved.

When Does it Start?

Timing is everything. We know—and countries have now agreed in the Paris outcome—that global emissions must peak as soon as possible and then decline even faster, and we must achieve net-zero emissions within the second half of this century.

In 2018, Parties will reconvene to take stock of their collective efforts (referred to as a “facilitative dialogue”). This facilitative dialogue will review progress made towards the long-term Paris Agreement goal to peak emissions and achieve net-zero emissions.

Based on the outcome of this facilitative dialogue, Parties will either submit new mitigation contributions (e.g. those whose current contributions contain a time frame up to 2025) or update their existing contributions (e.g. those whose current contributions contain a time frame up to 2030).

In addition, Parties have to submit plans for long-term decarbonization by 2020.

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Click to enlarge.

What Will Happen After 2020?

After the 2018 assessment, the next moment for all countries to come back and assess implementation and collective progress will be in 2023, referred to in the Paris Agreement as the “Global Stocktake.” This Global Stocktake will then occur every five years and serve as the pivotal collective moment to assess implementation and progress towards achieving long-term Paris Agreement goals.

The Global Stocktake has broad scope and purpose—assessing mitigation action as well as adaptation, means of implementation (including finance, technology transfer and development, and capacity building), and other support. Assessments will be based on equity and informed by the best available science, including the latest Intergovernmental Panel on Climate Change reports.

All Parties will be required to prepare and communicate new NDCs for mitigation, informed by the Global Stocktake outcomes. These new contributions will represent a progression, and reflect each Party’s highest possible ambition, taking into consideration equity and different national circumstances.

In 2028, the next Global Stocktake will occur, triggering another round of review for NDCs and progression in ambition. This review and revision process will continue every five years as a mechanism for strengthening ambition.

What About Adaptation and Climate Finance?

In addition to determining what the Global Stocktake will assess every five years, the Paris Agreement ensures a process for increasing adaptation action and the provision of climate finance.

Parties are encouraged to communicate their adaptation priorities, needs and efforts in a periodically updated cycle similar the one used for mitigation. Countries will have flexibility on timing and methods for communicating this information, but will continue to do so as a component of their nationally determined contributions every five years.

Developed countries are required, and other countries are encouraged, to communicate climate financing they have either provided or received every two years, and to indicate the levels of support they expect to provide or receive in the future.

The world has now embarked on a historic transformation. The regular and ongoing process to review and increase ambition across all elements of the Paris Agreement is what will ensure this is a historic, dynamic and durable outcome capable of driving the needed level of climate action.