Toward a Global "TRACC"? Climate Projections by Global Warming Levels in Worldwide Policy and Regulation

As climate impacts intensify, climate adaptation is quickly becoming a critical priority for governments, regions, and businesses worldwide. In response to the uncertainty surrounding future emission pathways, a growing number of actors are turning to climate projections defined by global warming levels (GWLs) rather than by grennhouse gases concentrations.

France has been among the early adopters of GWLs approach with the formalization of its Trajectoire de Référence pour l'Adaptation au Changement Climatique (TRACC), a national reference framework for climate adaptation, but similar methodologies are now emerging in multiple countries. This raises a broader question: should GWLs climate projections be coordinated at the international scale?

Global Warming Levels climate projections: a methodological shift rather than a paradigm change

Since the early development of climate modeling, most climate projections worldwide have relied on future greenhouse gas emission scenarios such as RCPs or SSPs used in the Fifth and Sixth IPCC assessment reports. These scenarios are used in climate models to simulate how key climate variables evolve over time under different emission pathways. In this framework, climate conditions depend on both the chosen scenario and the target time horizon and are often described as transient climate simulations.

Global warming level based projections take a different perspective. Instead of focusing on the specific emission pathway, they describe climate conditions associated with a fixed increase in global mean temperature such as +1.5°C, +2°C, or +3°C above preindustrial average. This approach provides a representation of climate conditions at a given warming level regardless of when that level is reached.

This methodological shift brings several benefits:

• A direct connection to the Paris Agreement. The targets of the 2015 Paris Agreement are framed in terms of global temperature thresholds rather than emission pathways: "Holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels". GWLs projections translate these abstract global targets into tangible climate conditions that decision makers can explore at regional and local scales.

By aligning climate impact assessments directly with Paris Agreement temperature goals, the warming level approach creates a clear bridge between international climate policy objectives and the real world impacts experienced by societies and economies worldwide.

• Addressing uncertainties. One of the main strengths of GWLs is that they avoid the need to choose to a specific emission scenario. The core assumption is that the climate impacts associated with a given level of global warming are broadly comparable regardless of when that level is reached or which pathway leads to it.

• A smooth methodological transition. In practice, adopting a warming level framework is relatively straightforward. As we saw in a recent tutorial, when conventional climate projections are already available, deriving climate information for a specific global warming level typically relies on simple post processing steps rather than entirely new modeling efforts.

The Global Warming Levels approach gained global visibility with the IPCC Sixth Assessment Report released in 2021, which explicitly assessed climate impacts at multiple global warming thresholds including 1.5, 2, 3, and 4°C above preindustrial levels defined over the 1850 to 1900 reference period.

The French Trajectoire de Référence pour l'Adptation au Changement Climatique: an early national benchmark based on GWLs

France has been among the first countries to formally adopt a warming level based approach within its national climate adaptation regulation. The shift was initially announced in early 2023 during the preparation of the Third National Adaptation Plan and was later enshrined in regulation in January 2026, establishing a legally recognized reference for climate adaptation planning.

The French framework defines explicit reference warming levels relative to the preindustrial period, with progressive thresholds set for the coming decades: +1.5°C by 2030, +2°C by 2050 and +3°C at the end of the century. These glowal warming levels are translated into regional warming levels for mainland France and its overseas territories

Regional warming	2030	2050	2100
Mainland France	+2.0°C	+2.7°C	+4.0°C
French West Indies	+1.4°C	+1.9°C	+2.7°C
French Guiana	+1.7°C	+2.3°C	+3.5°C
Réunion	+1.5°C	+2.0°C	+2.9°C
Mayotte	+1.5°C	+2.0°C	+3.0°C
New Caledonia	+1.5°C	+2.0°C	+3.0°C
French Polynesia	+1.2°C	+1.6°C	+2.3°C

This approach provides public authorities and economic actors with a shared and operational basis for anticipating climate impacts and guiding adaptation strategies.

Global Warming Levels outside of France: examples from Australia and Canada

Nearly one hundred countries worldwide have developed National Adaptation Plans, most of which still rely on conventional climate projections tied to emission scenarios. France is not alone however in exploring alternative approaches based on global warming levels.

Australia provides another example. Its National Climate Risk Assessment and National Adaptation Plan both released in 2025 explicitly adopt a warming level framework. Just like the French TRACC, they are based on global warming thresholds of +1.5°C, +2°C and +3°C relative to the 1850 to 1900 baseline, and also include an additional level representing current climate conditions at around plus 1.2°C.

These climate projections are shared with public authorities businesses and the wider public to support risk assessment and adaptation planning. Unlike the French TRACC however the Australian framework does not carry regulatory force and remains a strategic and informational reference rather than a legally binding standard.

Canada provides another illustrative example with a strong focus on the built environment. The Climate-Resilient Buildings and Core Public Infrastructure (CRBCPI) initiative launched in 2020 examines how climate change affects building and infrastructure design parameters using a GWLs based methodology.

The analysis identifies design parameters with clear and robust trends such as maximum temperature values referenced in the National Building Code of Canada and degree days below 18°C used in the Canadian Highway Bridge Design Code. Other variables including snow loads and wind pressures show weaker or more uncertain signals with substantial inter model variability.

Unlike the French TRACC, which provide only three GWLs, the Canadian approach explores seven distinct warming levels relative to the 1986 to 2016 baseline ranging from +0.5°C to +3.5°C. This finer granularity gives engineers and designers greater flexibility allowing them to tailor design assumptions to the expected lifespan of assets and to their chosen risk tolerance.

For projects with a service life of 50 years, the report recommends using the +2.5°C global warming level relative to the 1986 to 2016 average. Due to difference in methodologies, this level is actually higher than the +3°C/+4°C referenced by the French TRACC.

Direct comparisons of GWLs between countries require caution because different reference periods can be used used. The Canadian analysis is anchored to a recent historical baseline 1986 to 2016 while other frameworks such as the French TRACC express warming levels relative to the preindustrial period 1850 to 1900 or to early twentieth century baselines.

When accounting for the approximately 0.8°C of warming that had already occurred by 1986-2016, the +2.5°C recommended by the CRBCPI for 50-year projects roughly translate into +3.3°C relative to the pre-industrial era. This GWL is therefore significantly higher than it may seem at first glance, for example it is higher than the +3°C projected by the French TRACC for the year 2100, reflecting a significantly more pessimistic (or more cautious) approach by Canada.

The Need for harmonized international standards for GWLs based climate projections

This divergence highlights the growing need for international harmonization. It is easy to imagine the confusion faced by a company operating sites in multiple countries, with assets in France designed using standards based on a global warming level of +3°C relative to the preindustrial era, while assets in Canada are designed using a +2.5°C benchmark... that is in fact more stringent because it is referenced to the 1986-2016 period rather than 1850-1900.

Without a shared reference framework, warming level based approaches risk creating inconsistencies that undermine their very purpose, particularly for multinational organizations seeking coherent and comparable adaptation strategies across regions.

Developing realistic and coherent adaptation scenarios

The Paris Agreement established common benchmarks by defining the +1.5°C and +2°C targets relative to the preindustrial era. These thresholds already function as a shared language among countries and institutions. However, they correspond to optimistic warming outcomes. Current global emission trajectories instead point toward higher levels of warming in the second half of the century, around +3°C or more.

As a result, adaptation policies must consider at least one additional, more realistic warming level beyond the ambitious but increasingly difficult to achieve Paris targets. Coordinating these reference scenarios at the international level would have obvious benefits for the consistency and credibility of adaptation planning.

This need for harmonization is particularly acute in the European context. The European Union, through the Green Deal and its adaptation strategy, relies on alignment between member states. Divergent national climate frameworks in countries such as France, Germany, Spain, or the Netherlands would complicate the development of common European standards for cross border infrastructure, energy systems, and building regulations. They would also limit the ability to transfer adaptation solutions and best practices from one country to another.

Enabling consistent assessments for multinational organizations

More broadly, for companies operating across multiple countries, the absence of shared and harmonized GWL based frameworks would generate additional costs and operational complexity.

The implementation of the TRACC has already raised questions among many foreign companies with operations in France, as they grow uncertain whether their existing adaptation strategies, risk management frameworks or business continuity plans remain valid under the new regulatory requirements.

Conversely, while French regulations require TRACC compliant climate projections to be provided free of charge by Météo France, this obligation applies only within the national territory. French companies therefore face a different challenge when managing international assets, as they lack access to equivalent warming level based projections outside France. This raises questions about how to ensure methodological and data consistency across all foreign operations.

The divergence already observed between France and Canada could intensify rapidly as warming level approaches are adopted in additional jurisdictions. Without coordination, this trend risks creating fragmented standards, increasing costs and adding unnecessary complexity for international organizations. By contrast, a shared international framework would enable companies to develop transferable adaptation strategies and scalable solutions across countries, supporting a more efficient transition toward a climate resilient economy.

The imperative of a common methodology

Beyond the choice of scenarios themselves, agreement on shared methodological foundations is essential.

1. Reference periods. As discussed earlier, the French TRACC uses the preindustrial era 1850 to 1900 as its reference, while the Canadian CRBCPI relies on the 1986 to 2016 period. This discrepancy complicates comparisons and can easily lead to misinterpretation. Adopting a common reference period would significantly improve international consistency. The 1850-1900 preindustrial baseline appears to be the most natural candidate, as it is already used by the IPCC and embedded in the Paris Agreement.
   

2. Warming level selection. The +1.5°C and +2°C levels defined by the Paris Agreement serve as universal benchmarks, but they offer limited guidance for climate risk management. The key question is which warming levels should underpin more realistic adaptation scenarios. Should frameworks favor a simple structure with a small number of reference levels, as in the TRACC, or a more granular approach like the CRBCPI that allows choices to be tailored to asset lifespans and risk profiles? One point is clear. References to regional warming levels, such as the +4°C figure used for mainland France in the original TRACC framing, should be limited to awareness raising purposes and systematically associated with an equivalent global warming level.
   

3. Time horizons associated with warming levels. Some countries, such as France, associate explicit time horizons with their warming levels, for example +2°C by 2050 or +3°C by 2100. Others, like Canada, prefer to let engineers and asset owners select appropriate warming levels based on the expected lifetime of a project and its acceptable level of risk. A hybrid approach could combine indicative time horizons with sufficient flexibility, while acknowledging the deep uncertainties surrounding future emission and climate.
   

4. Governance and review. Climate scenarios must be regularly updated to reflect observed emissions trends and scientific progress. This requirement is mentioned in the recent French regulation but remains only partially specified. An international governance and review mechanism, aligned with the IPCC assessment cycles, could help ensure the long term relevance, credibility, and consistency of warming level based frameworks.

Using global warming level based climate projections represents a major step forward in climate adaptation planning. France’s pioneering experience with the TRACC demonstrates the feasibility of this approach, and its effectiveness in guiding decisions related to buildings, infrastructure and urban planning will soon be tested in practice. If successful, it could pave the way for the emergence of a shared international framework for climate adaptation.

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Whether you need to comply with the newly adopted French TRACC or assess the compatibility of your organization’s vulnerability studies with emerging climate regulations worldwide, access to consistent GWLs based climate projections is becoming essential.

ClimateVision, the climate intelligence solution developed by Callendar, enables you to generate comprehensive climate projections for any location worldwide, across all global warming levels from +1.2°C to +5°C (relative to the preindustrial era), in just a few hours.

Get in touch to explore how Callendar can support your adaptation and risk management strategies.