Understanding the context
We Know
The IPCC: Science in the Service of the Climate
For more than 30 years, the IPCC (Intergovernmental Panel on Climate Change) has been assessing the current state of knowledge regarding climate change, its causes, and its impacts. It also identifies ways to limit the extent of global warming and the severity of its impacts, as well as to adapt to expected changes. The IPCC’s reports provide a regular update on the most advanced scientific understanding and are now central to international climate negotiations. This work is also essential for raising awareness among policymakers and civil society.
The National Low-Carbon Strategy
Our Compass Toward a Low-Carbon Economy
The National Low-Carbon Strategy (SNBC) is France’s roadmap for combating climate change. It aims to achieve carbon neutrality by 2050 and reduce the carbon footprint of French consumption. It provides guidance for implementing the transition to a low-carbon, circular, and sustainable economy across all sectors. It outlines a trajectory for reducing greenhouse gas emissions through 2050 and sets short- and medium-term goals: the carbon budgets.
Biodiversity
The Essence of Our Regions
Current climate change is altering the interactions between species and their habitats within ecosystems. With global warming of 2 to 3 °C, experts predict an increased risk of extinction for 20 to 30 percent of animal and plant species. The Law for the Restoration of Biodiversity, Nature, and Landscapes established the goal of reducing net biodiversity loss to zero. The Biodiversity Plan, for its part, aims to implement this objective and is designed to strengthen France’s efforts to preserve biodiversity and, for the first time, mobilize measures to restore it when it has been degraded.
Zero net land development
The History of Land Use in France
Enacted in 2018 as part of the Biodiversity Plan and enshrined in the Climate and Resilience Act in August 2021, the initiative aims to minimize urban sprawl and halve the consumption of natural, agricultural, and forested areas by 2030, with the goal of achieving net-zero land conversion in the longer term—by 2050. A government roadmap, currently being developed, is intended to establish a timeline and a path toward achieving this goal. A national observatory is then expected to be established in 2024 to monitor these developments.
Planetary Boundaries
The concept of planetary boundaries was defined in 2009 by an international group of 26 researchers with the goal of better understanding the “Earth system.” It offers a comprehensive, cross-cutting view of global risks because it allows us to track the interactions between these different domains.
There are nine planetary boundaries: climate change, biodiversity loss, disruption of the biogeochemical cycles of nitrogen and phosphorus, changes in land use, ocean acidification, global water use, stratospheric ozone depletion, increased atmospheric aerosols, and the introduction of new entities into the biosphere.
Planetary boundaries represent thresholds beyond which the Earth’s habitability for humans could be jeopardized. Crossing each boundary increases the risk of irreversibly destabilizing the global environment, with major impacts on living organisms. Today, six planetary boundaries have been exceeded.
The Paris Agreement: 2 metric tons of CO2 equivalent target
The Paris Agreement is a legally binding international treaty that marks a turning point in the fight against global warming. It was adopted by 196 parties at COP21 in Paris on December 12, 2015, and entered into force on November 4, 2016. It set a goal: to limit the rise in temperature to below 2 degrees by 2100.
To achieve this, we must reduce our greenhouse gas emissions in order to reach carbon neutrality by 2050. This means, in particular, reducing emissions to 2 metric tons of CO2 equivalent per person per year by 2050 (compared to 10 metric tons today).
What about in the mountains?
The mountains are not spared by global warming. The impacts seem even more visible than elsewhere: melting of the glaciers, less snow cover at low and medium altitudes, disturbance of the biodiversity, thawing of the permafrost and rockslides.
As concerns the impact of carbon emissions, the mountain regions are particularly concerned because of visitor travel and the heating of accommodation at altitude. According to the carbon assessment performed by consultant UTOPIES for La Plagne in 2022, visitor transport, food and accommodation represents 88% of the resort’s greenhouse gas emissions (initial estimations).
Le contexte :
Des études sont réalisées sur le bilan de masse des glaciers : différence entre la neige accumulée et la fonte (accumulation VS ablation). Selon l’ONERC* en 2023, en moyenne et en 20 ans (entre 2002 et 2021) : les cinq glaciers suivis (Ossoue, Gebroulaz, Argentière, Saint Sorlin, Mer de Glace) ont perdu -25 mètres d’équivalent eau.
*Observatoire national sur les effets du réchauffement climatique
Les conséquences :
La fonte des glaciers a un effet sur le climat lui-même via l’effet d’albédo : la capacité d’une surface à refléter, en fonction de sa couleur, les rayons du soleil vers l’espace. En fondant, la glace expose les surfaces de la Terre qui absorbent alors les rayons du soleil et provoque donc une accélération du réchauffement climatique. Selon Météo France, les montagnes se réchauffent 2 fois plus vite que le reste du pays (2°C au cours du XXe siècle pour les Alpes et les Pyrénées VS 1,4°C pour le reste du pays).
Par ailleurs, si la fonte des glaciers n’a pas d’impact significatif sur la montée du niveau de la mer (contrairement à la fonte des calottes polaires en Antarctique ou au Groenland), il en a un sur la ressource en eau douce. Effectivement, la fonte des glaciers entraîne une diminution de la capacité de stockage de nos territoires en eau douce. L’eau va ruisseler, s’évacuer et ne sera plus stockée (et « relâchée » en été par exemple). La fonte des glaciers peut aussi avoir d’autres conséquences : formation de lacs glaciaires et risques d’inondation, libération de gaz à effets de serre due à la fonte du permafrost…
