"Trump's decision, which was dictated by an internal political choice, looks very much like a climate Brexit," Royal, who was environment minister at the time of the Cop21 meeting in Paris that led to the dea l, told the Journal du Dimanche newspaper.
The British "shot themselves in the foot" in voting to leave the EU, Royal commented, adding that the "radical nature of [Trump's] Thursday decision took us by surprise".
Claiming that there is no legal mechanism for sanctions against over the decision, she said that the US is already suffering by "losing leadership, credibility with the most vulnerable countries and the emerging major powers", as well as "destablising" its own industry.
With 147 countries having ratified the accord, Royal said there was a risk that other countries could follow the American example, "especially since Russia has not yet ratified" it.
To read our coverage of the Cop21 climate change accord click here