Climate: without strong actions, big warming in sight according to Météo-France

If nothing is done quickly to limit greenhouse gas emissions, France is threatened by strong global warming, with its procession of heat waves and droughts, according to projections published Monday by Météo-France.

In the midst of controversy over the level of ambition of the bill resulting from the Citizen's Climate Convention and while a decision is expected this week in the proceedings brought by several NGOs against the State for climate inaction, the worst scenario studied places the Metropolitan France on a trajectory of +3.9 degrees compared to the average temperature of the reference period (1976/2005).

In the worst case scenario, the heat waves would be multiplied by 10

That is well beyond the objectives of the Paris agreement to limit warming "well below 2 ° C compared to pre-industrial levels", if possible below 1.5 °.

However, according to experts, warming since the pre-industrial era is already approaching one degree.

And France, which has pledged to reduce its emissions by 40% by 2030 compared to 1990, exceeded the carbon budgets it had set itself.

Météo-France, whose boss Virginie Schwarz recalls in the introduction to this new publication that "all the observations collected on a planetary scale confirm an unprecedented acceleration of climate change", worked with the Pierre Simon Laplace Institute and the European Center of research and advanced training in scientific computing.

From models carried out for the UN, the researchers made projections according to three scenarios of UN experts from the IPCC (controlled, moderate or non-reduced greenhouse gas emissions) and at three time horizons - 2050, 2070 and 2100. The data, posted on www.drias-climat.fr, are worked on at the regional level, with the objective of promoting work on adaptation to climate change in the regions.

At the national level, warming is contained, in the three scenarios studied, at around 1 degree until 2040. The trajectories then diverge sharply.

If the increase is stabilized around + 1 ° in a controlled emissions scenario, the increase reaches + 2.2 ° on average in the intermediate scenario and soars to + 3.9 ° on average (and +4, 5 ° at worst) in the high emissions scenario.

The absolute records recorded during the heatwave of summer 2019 - with 46 degrees in the south of France - could then be often exceeded, with an increase in average summer temperatures of 6 degrees.

In the worst scenario, the heat waves would be multiplied by 10.

Drought episodes are expected to increase

And even in the hypothesis of controlled emissions, the number of days of heat waves (more than 5 consecutive days at more than 5 ° above the average) could double.

As for "tropical nights", when the temperature does not drop below 20 degrees and undermines the recovery of the human body, the researchers project that in the worst scenario "at the end of the century, only the mountain areas and the coast of the Channel remain almost untouched while the increase reaches 90 days in the most exposed areas ".

For their part, drought episodes increase by 30 to 50% in the medium and high scenarios.

And this even if the evolution of the precipitation regime is more difficult to predict, expected to increase slightly in winter but sharply decrease in summer (more than 20% in the worst scenario).

Side extreme weather phenomena, researchers face "uncertainties", but warn about the possibility of increasing the intensity of extreme rains, or strong winds in the northeastern quarter of the country.

Conversely, snow and frost in winter could pass to the rank of memories.

Regionalized projections show an increase in the average annual temperature of up to 6 degrees in certain areas of the Alps and the Pyrenees.