The nuclear test program of France (1960-96) was not compatible with the enmod convention of 1977/78.
France had a 15 years “delay” of developing nuclear weapons and they had a “need to catch up”.
France did not sign the Partial Nuclear Test Ban Treaty, which gave it the option to conduct further nuclear tests until it signed and ratified the Comprehensive Nuclear-Test-Ban Treaty in 1996 and 1998 respectively.
From 1960 to 1996, France carried out 210 nuclear tests, 17 in the Algerian Sahara and 193 in French Polynesia in the South Pacific, symbolised by the images of a mushroom cloud over the Mururoa atoll. For decades, France argued that the controlled explosions were clean. Jacques Chirac, the French president, controversially resumed nuclear atoll explosions in the South Pacific shortly after being elected in 1995.
The reasonings in the article (s. Link of Denis de Bernardy’s comment) are rather hypocritical as we know all weapons and all nuclear tests have been destructive for the environment. The environmental impact was not just a side effect - it was one of the goals of the atomic bomb.
France's rejection in 1977 is part of a general disarmament policy that is defensive, reactive and selective (La Diplomatie Française du Désarmement sous la Vème République, Daniel Colard). Similarly, France did not ratify the Non-Proliferation Treaty at that time. It did not become a party until 1992. However, France never signed the ENMOD agreement later. France has not acceded to this agreement because it believes that its text contains inaccurate provisions which make it uncertain to apply, particularly with regard to nuclear deterrence (see above). France, as a party to Additional Protocol I to the Geneva Conventions and other disarmament treaties, continues to be bound by these commitments. In addition, a breach of France's obligations under the ENMOD Convention is hardly conceivable. Aside from the fact that France is currently not involved in the research of these techniques, it is very likely that the commitments contained in the Convention will be a custom if it is not international, at least regional, is the vast majority of the Member States of the European Union Political party.
Especially the last phrase is simply a lie, if we consider what happened on the Murora island and in the desert of Algeria!