Climatic change: our knowledge and uncertainties

After a long career as a research scientist, Éric Brun-Barrière, since 2014, has been Secretary General of the FrenchNational Observatory on the Effects of Global Warming (ONERC) at the Ministry of Ecological Transition. On September 1st, he gave the first inaugural lesson at the UTC of the autumn of 2020.

Climatic change: our knowledge and uncertainties

Graduate from Ecole Polytechnique, Éric Brun-Barrière was very quickly interested in the climate, particularly snow. "A personal passion", he says. This passion paved his way to Grenobles, to the Centre d'études de la neige, Météo France/CNRS research centre where he studied, in particular, the interactions between weather, climate and the state of the snowpack. "At the time, there was hardly any talk of climate change. What we were interested in was understanding the influence of weather conditions on the formation of a more or less stable snowpack to improve the predictability of avalanche risk", he explains. A passion that has also enabled him to developed, a world first, the the first tool for the numerical simulation of the snow mantle. "It allowed us to describe with a reasonable degree of accuracy the internal state of the snowpack - its temperature, the type of crystals composing each of its layers, its density, etc.,. at a given point in time and thus be able to assess its stability in relation to the risk of avalanches. All this is done using weather data collected from the beginning of the snowpack formation," he says.

A tool that makes it possible to formalise all the knowledge accumulated and which has opened up a new avenue of research for all countries faced with this type of risk. It has also found new application with the rise of the debate on climate change. "The idea is to digitally simulate the state of the snowpack with the hypothesis that, instead of winters as we know them, we would have winters 1.5 to 2°C warmer. What applies to the mountains also applies to the great plains such as can be found in Siberia or Alaska, whose cooling power for the planet is recognised", underlines Éric Brun-Barrière.

After a period at the Centre de Météo France in Toulouse, which he managed for almost 7 years, he resumed research on the interactions between climate and snow. “Climate models are based on extremely complex numerical codes with the component parts - atmosphere, vege t a t ion, sea, snow, etc. This can amount to almost a million lines of code. I have worked in particular on the implementation of snow models that are sophisticated enough to fully understand the feedback and then make more reliable climate simulations. Today, our knowledge is certainly immense, but the uncertainties are still numerous and are subject to intense research to clarify them", he says.

In 2014, he ends his research career and joins the Ministry of Ecological and Solidarity Transition, appointed to ONERC. "I decided to dedicate my knowledge to public policies in the fight against global warming. I have two main missions. The first concerns national policy in regard to adapting to climate change, i.e. i.e. to prepare society for climate change in France at 50 or 100 years from now. The second is to act as an interface between the IPCC and the French government," concludes Éric Brun- Barrière.