In the face of climate change, what long-term responses are there?
A few months before the 21st climate conference (Paris Climate of 2015), the 5th volume of the report on "The Climate of France in the 21st Century" was submitted to our Minister of the Environment, Ségolène ROYAL.
This report launched in 2010 and led by Jean JOUZEL, a member of the IPCC (Intergovernmental Panel on Climate Change), aims to provide the scientific knowledge necessary to understand the impacts of climate change in France. The 5th volume provides, among other things, forecast elements on the rise in sea level: according to IPCC projections, between the periods 2081-2100, the global mean sea level rise is likely to be between 26 and 55 cm for the most optimistic scenario. Marine submersion and coastal erosion are natural processes that could be exacerbated by this rise in sea level.
These results lead us to question the long-term solutions that could limit these phenomena. Among the recommendations from JOUZEL are measures to avoid increasing exposure to coastal risks.
Unclear solutions in public policies
However, no details are provided on the measures to be developed or their nature. Nature-based solutions, popularized by the IUCN, are based on the idea that natural habitats provide services that may be more effective in addressing major global climate challenges as well as those of food and development.
But can natural habitats really replace the policies and major developments that humanity has taken decades to establish? Carbon tax to reduce CO2 levels in the atmosphere; dikes to limit marine submersion; breakwaters to slow coastal erosion? Are nature-based solutions currently being used as alternatives to measures against the effects of climate change? And are they more effective than more "conventional" measures?
The example of Graveyron: when nature protects better than concrete
This question was recently addressed by Vertigo Lab. As part of its study on the benefits of the Coastal Conservatory sites, Vertigo Lab indeed focused on the choice made by the managers of the Graveyron estate to allow depoldering against public opinion favoring a restoration of the dike.
This choice has resulted in the development of a gentle land-sea transition based on nature. Estimates show that this depoldering has allowed the return of a salt marsh whose absorption capacity in the event of marine submersion could limit damage related to marine submersion and thus reduce post-submersion damage costs by 3.6 million euros.
More effective... and often less costly solutions
In addition to often being more effective than anthropogenic solutions, nature-based solutions can also be a source of savings: their naturalness, ensuring autonomy and resilience in service provision, helps reduce costs associated with human intervention.
These so-called opportunity costs are equivalent to the costs of the infrastructures that would have been necessary to provide the same service in the absence of these solutions.
A potential still largely underutilized
The potential of nature-based solutions, reaffirmed in this article, can only be harnessed in the future through a better understanding of the benefits offered by the services they provide and maintaining ecosystems in good condition.
