Carbone 4’s Response to the Consultation on the Draft Reference Warming Trajectory for Climate Change Adaptation (TRACC)

Following the public consultation launched by the Ministry of Ecological Transition on the draft reference warming trajectory for climate change adaptation (TRACC), Carbone 4 provides insights based on its nine years of experience supporting economic actors in adapting their activities to the impacts of climate change.

Should France establish a reference warming pathway by the end of the century for adaptation purposes, while continuing its efforts to reduce greenhouse gas emissions in line with the goals of the Paris Agreement?

Climate change is already a reality, with temperatures rising by +1.1°^[1] on average worldwide over the past decade (2011–2020) compared to the preindustrial era. Its effects are already being felt, particularly in France, as seen in the summers of 2022 and 2023, which were marked by severe heat waves. An adaptation policy is therefore already necessary to minimize the impacts of current climate change as much as possible.

With regard to the future climate, global efforts to reduce greenhouse gas (GHG) emissions are currently far from sufficient to comply with the Paris Agreement and keep global warming well below 2°C compared to pre-industrial levels. The commitments made to date by countries at the COP climate conferences are projected to result in global warming of approximately 3.2°C.^[1] . However, since climate change is a global phenomenon, France’s future climate depends on global GHG emissions—and thus, overwhelmingly, on the measures other countries take to reduce their own emissions. While France must aim to reduce its own GHG emissions to comply with the Paris Agreement and encourage other countries to follow suit, we cannot rely solely on the assumption that all countries will take action to keep global warming below 2°C. France therefore has little control over what its climate will be like in the coming decades.

Furthermore, the fight against climate change faces obstacles worldwide—including in France—due to both societal inertia, with the changes needed to comply with the Paris Agreement slow to materialize, and physical inertia, notably rising sea levels, a phenomenon characterized by significant inertia that will occur regardless of our current and future efforts to reduce GHG emissions. Furthermore, while climate science provides increasingly accurate projections, our understanding of the climate and its impacts remains incomplete. Significant uncertainties remain both regarding the level of warming that may be reached for a given GHG concentration and regarding the consequences of climate change on the functioning of human societies for a given level of warming. These various factors therefore mean that we cannot rule out the possibility of reaching warming levels well above +2°C during this century.

Given the potential—and in some cases irreversible—impacts that such levels of global warming could have on our societies, Implementing a climate change adaptation policy is therefore essential to collectively prepare for this possibility, without this leading to any reduction in the level of ambition we must maintain regarding the reduction of anthropogenic GHG emissions.

In this context, and given the high degree of interdependence that exists today among the country’s various stakeholders (local governments, the national government, businesses, and civil society) in a globalized economy, the consequences of climate change are and will be systemic: a hazard affecting a given locality can have a significant indirect impact on stakeholders on the other side of the world^[2] For example. Adaptation to climate change can therefore only be effective if it takes a systemic, cross-sectoral approach, ensuring that the actions of each entity are coordinated to form a more resilient whole. A Common Frameworkis therefore necessary to facilitate dialogue among the various institutional and economic stakeholders that are interdependent with one another. Establishing a reference warming pathway is an essential building block to be established in order to define this common framework so that everyone can plan for the same level of global warming and develop robust and consistent adaptation plans at the level of each region and each sector. This will also provide a common basis for comparing the potential impacts and measures undertaken by each entity.

The example of the measures and mechanisms to be considered for reducing our GHG emissions clearly illustrates the need for a reference trajectory. Indeed, a significant portion of the actions required to comply with the Paris Agreement involve investments. However, it would be counterproductive and economically ill-advised not to factor in the climate conditions under which these investments will operate. The availability of TRACC will make it possible to provide this projection of future climate conditions—particularly for medium- and long-term initiatives, where uncertainties are greater—and thus enhance the relevance and effectiveness (both physical and economic) of the investments made.

Finally, while there is an urgent need to implement an adaptation policy that is commensurate with the challenges posed by climate change, it is nevertheless important to keep in mind that Adaptation to climate change has its limits : We will not be able to adapt to just any climate. Indeed, adaptation aims to preserve the capacity of social, economic, or environmental systems to cope with a disruption, a trend, or a hazardous event. This is not always possible, and climate change can therefore lead to irreversible consequences: losses and damages. This is already the case, particularly in certain coastal regions (including in France), where the expected rise in sea level cannot be countered by any adaptation measures, leading to population displacement. The greater the global warming, the more difficult it will be to adapt, and the greater the losses and damages will be. This is why adaptation can in no way replace efforts to mitigate climate change (reducing GHG emissions).

What do you think of a reference warming trajectory for France’s adaptation (TRACC), with reference warming levels of +1.5 °C in 2030, +2 °C in 2050, and +3 °C by 2100 globally—which would correspond to a warming level in metropolitan France of approximately +2 °C by 2030, +2.7 °C by 2050, and +4 °C by 2100 compared to pre-industrial levels?

While the implementation of a TRACC is a step in the right direction to support France’s adaptation to climate change, several points can be raised regarding the choices presented in the consultation.

First, regarding the format, the TRACC report mentions both global warming levels and those for Metropolitan France; the latter are higher, as France is warming faster than the rest of the world. We see a significant risk of confusion in using these two reference frames simultaneously to present the trajectory, as one could easily be mistaken for the other. We therefore propose to include only a presentation of the trajectory specifying the level of global warming Given that the vast majority of publications related to climate change are expressed in this framework (starting with the IPCC reports). Furthermore, we now operate in globalized economies where every actor has direct or indirect dependencies on physical flows located abroad. A systemic analysis of each actor therefore again calls for reasoning based on a level of global warming expressed on a global scale.

Furthermore, while it makes sense to describe trends in terms of temperature deviations from the preindustrial period—given that this is the standard used in climate science—we believe it would be helpful if the datasets made available (through the DRIAS Climat and DRIAS Water) provided data expressed as deviations from the present period. This would make the data easier for various stakeholders to understand: it is easier to visualize future trends by comparing them to what we know today rather than to a past situation that no longer corresponds to the current climate. This is not the case today, for example, with the reference period centered on 1990 on DRIAS-Climate.

Next, on the substance, The proposed trajectory does not appear pessimistic in light of current trends and the latest climate projections; rather, it is closer to an upper-middle scenario for the 2050 and 2100 time horizons.

In fact, based on the main scenarios detailed in the latest IPCC report, the SSPs (Shared Socio-economic Pathways)^[3], the two most pessimistic scenarios (SSP3-7.0 and SSP5-8.5) indicate global warming levels that exceed the TRACC threshold by 2050 and 2100 (see table below, excerpted from the consultation document). However, these two scenarios—which reflect the failure of mitigation policies and the continuation of trends in primary energy consumption and the energy mix—appear likely by 2050, given the societal inertia mentioned above. By 2100, reaching these GHG emission levels is not the most likely outcome, but it cannot be ruled out either.

Furthermore, in addition to the uncertainty regarding the future ability of human societies to reduce GHG emissions, there is also uncertainty related to climate modeling. This modeling uncertainty implies that certain levels of warming could potentially be reached even under scenarios with lower GHG emissions if climate sensitivity exceeds the median value of current models.

Finally, for a given level of global warming, modeling the impacts that climate change will have on the functioning of our human societies (crops, river levels, the condition of infrastructure inland or along the coast, the ability to work or find shelter throughout the year, mortality due to the wet-bulb effect, the spread of diseases, etc.) also involves numerous uncertainties.  Moreover, one of the key conclusions of the IPCC Working Group II AR6 report is that the consequences of climate change (in terms of risks to human societies and natural ecosystems) were underestimated in the previous report (AR5). In the field of risk management, our priority is to prepare for and mitigate the most significant risks; this means, at a minimum, having a trajectory that allows stakeholders to prepare for these extreme events that are low in probability but high in impact. We therefore do not believe it is appropriate to reserve this type of approach solely for certain critical points, as currently envisaged in the consultation.

A serious adaptation strategy must therefore take these uncertainties into account by not focusing solely on the median value of current projections, but by considering higher levels of warming, This is something that the currently proposed TRACC does not do; it examines a warming level that lies midway between current policies and the commitments announced by countries (corresponding to the SSP3-7.0 and SSP2-4.5 scenarios, respectively).

Furthermore, beyond the selected warming level, we recommend adopting an adaptation approach that assesses risks based on at least two warming trajectories.^[4] In fact, relying solely on the most pessimistic GHG emissions scenario is not necessarily the best choice. This approach has the drawback of obscuring the forward-looking nature inherent in climate scenarios, since only a single perspective is considered, and there is a risk of conflating foresight with prediction. Furthermore, this approach can have unintended consequences, such as discouraging teams given the scale of the problem, causing decision-makers to question the scenario’s plausibility—which in turn leads to delays in taking action—or, worse still, abandoning mitigation efforts to focus exclusively on adaptation. We therefore recommend using at least two trajectories to capture the sensitivity of risks to the warming levels under consideration and to map out the range of possible climate change impacts, using: a trend-based warming level (which may correspond to the warming levels proposed in the consultation) and a more pessimistic scenario (close to SSP3-7.0 or SSP5-8.5).

What tools and support are needed for the major initiatives that have been identified (updating standards, guidelines, and technical regulations; adapting local governments; and adapting economic sectors)?

With regard to the tools made available to various stakeholders for climate change adaptation, the DRIAS Climat, DRIAS Eau, Climat HD, and Climadiag portals are relevant and useful resources for successfully implementing this type of initiative. Updating these portals to incorporate TRACC warming levels as calculation assumptions will be a significant step forward in enabling various stakeholders to carry out their adaptation efforts in line with this reference trajectory.

Nevertheless, further action appears necessary to ensure that this issue is given greater consideration and that it is implemented effectively and in a harmonized manner by the various stakeholders in the region. As mentioned in the response to Question 1, establishing a common framework is an essential prerequisite for ensuring dialogue among various interdependent stakeholders and, ultimately, collective resilience in the face of climate change. Establishing a reference trajectory is a good first step toward defining this common framework, but the framework itself must be broader. Given the wide variety of available data and the different sets of models used, We believe it would be appropriate to have guidelines that would help harmonize the approaches of the various stakeholders regarding the use of climate data. The DRIAS portal launched today is already useful, but it hosts a fairly diverse set of datasets, and the precautions for using this data are not explicit enough; the instructions are incomplete. In practical terms, this would mean, for example, providing guidance for each specific scenario (climate-related hazards,^[5]  (time horizon, scenarios analyzed, etc.) regarding the recommended datasets and the quantiles to be used, while transparently indicating the level of confidence and the limitations of the exercise.

Furthermore, the availability of climate data is highly relevant and useful for studying so-called “direct” climate hazards, but These datasets will also need to be supplemented with data from impact models for so-called “indirect” hazards. This is already the case on DRIAS-Eau for risks related to river flooding, for example, based on data from the Explore2 initiative, but it should be expanded to include other indirect hazards (clay shrinkage and swelling, landslides, flooding, inundation, etc.).

Regarding the updating of standards and guidelines, using TRACC to update the various technical regulations, standards, and guidelines seems appropriate as a way to prepare for future climate conditions. This will also improve the efficiency of public spending by ensuring that today’s public investments are adapted to the climate conditions they will face throughout their entire lifespan.

However, simply referring to TRACC is not enough to establish standards or frameworks that effectively contribute to our collective resilience. The use of TRACC does not replace the regulator’s thorough understanding of the various physical processes at work and the different possible methodological approaches. The implementation of TRACC will nevertheless enable these different methods to share a common framework and be more easily interoperable.

We have identified three key success factors to ensure the proper implementation of changes to standards:

1. sufficient support for institutional and economic stakeholders to ensure efficient implementation in each sector and locality,
2. the establishment of appropriate monitoring capabilities to track the implementation of these new regulations
3. the establishment of reporting requirements regarding adaptation measures, similar to those currently being implemented for GHG emissions.

Furthermore, climate change is a multifactorial risk for communities and businesses. We therefore suggest that the updating of standards and guidelines not be limited to adjustments based solely on TRACC, but that it also incorporate the analysis of climate shock scenarios.^[6]that allows us to capture this systemic scope (spatial and/or temporal combinations of climate hazards) as well as the study of low-probability, high-impact events. This point was highlighted, in particular, in an article published in 2022^[7] by several researchers, who explain that, given the accelerating pace of climate change, it is not enough to explore the most extreme warming scenarios; we must also take into account the potential for chain reactions.

With regard to the adaptation of economic sectors to climate change, we believe it is appropriate to conduct a physical climate risk analysis based on the TRACC framework for each sector of activity. However, it will be necessary to fully account for the interdependencies between each sector in order to ensure the overall coherence of the adaptation strategy.

At the operational level of each company, methodologies such as the OCARA framework^[6]  can be implemented using TRACC as a baseline scenario. The OCARA method makes it possible to understand, identify, and prioritize weak or strong signals of climate change based on a holistic view of impacts. This methodological framework is therefore not limited to studying the direct impacts of climate change on the company’s sites—which represent only part of the problem—but allows for consideration of all the disruptions that climate change may cause on the corporate value chain.

Once again, using a TRACC with global warming scenarios will make it easier for French companies to assess the potential consequences of climate change on their upstream and downstream value chains, most of which are not located in France. The method provides a tailored classification of organizational processes, an action-oriented analytical framework, and practical tools for developing adaptation and resilience plans. In our view, financial assistance provided to economic actors to help them receive training in this type of methodology could enable them to effectively adopt and apply TRACC.

The establishment of forums for dialogue at the local level We also believe this is an important factor in fostering dialogue among highly interdependent stakeholders (including businesses, network operators, and public utilities) and enabling them to adapt collectively.

Finally, the fact that the implementation of TRACC places particular emphasis on preserving ecosystems and biodiversity in the face of climate change is a highly relevant point, given the interconnections between climate change and biodiversity. Extending this line of thinking to all planetary boundaries (land-use change, freshwater resources, nitrogen and phosphorus biogeochemical cycles, etc.) would ensure a consistent rollout from a broad environmental perspective.