Haim Korsia, 51, who was elected Chief Rabbi of France last Sunday, will preside over a shrinking Jewish community. From a Jewish population of 500,000 or so - the largest Jewish community in the European Union - it may quickly fall to 400,000, or even less.
According to Natan Sharansky, the Jewish Agency Chairman, 2,254 French Jews completed aliyah during the first five months of 2014, against only 580 last year; a staggering 289 per cent increase. By December 31 this year, the total may be well over 5,000. Not since the Second World War has a Western country provided Israel with such immigration rates.
Moreover, a second group of French Jews is engaging in "gradual, informal immigration" - without applying for citizenship, they buy apartments in Israel, register their children at Israeli universities, commute between France and Israel for business, or come as "frequent visitors" on retiring.
"At the end of the day, many of them are likely to stay as fully fledged immigrants", a French-Israeli sociologist said. Actual French immigration to Israel may thus be closer to 6,000 or 7,000 a year.
And what about a third group : French Jews who emigrate to other countries? That is gaining momentum. Affluent people are transferring their homes and offices to the UK, Belgium or Switzerland. Young professionals go to the UK, the US, Canada and East Asia. Berlin, a top destination for Israelis, is attracting French Jews, too.
Joel Mergui, the lay chairman of Consistoire, the National Union of French Synagogues, concedes: "You can feel the bite at every level." Emigration means less worshippers, less kids at school, less donations for Jewish charities. "At some synagogues, whole benches are suddenly empty."
Antisemitism is the main reason why French Jews are leaving. Two years ago, a French-born jihadist trained in the Middle East murdered one teacher and three children at point blank range at a Jewish school in Toulouse, in southern France. A couple of weeks ago, another French-born and French-based jihadi was involved in the massacre at the Jewish Museum in Brussels.
More violence occurs on an almost daily basis, according to Samuel Ghozlan, a retired police commissioner who founded BNVCA, an antisemitism monitoring organisation. Jews are also worried by the rise of the far right National Front (who won one third of the French seats at the European Parliament last month), even if its current leader, Marine Le Pen, is eager to distance herself from her father Jean-Marie Le Pen's antisemitic rhetoric.
Even more ominously, a new brand of explicit, "national-socialist" antisemitism is now very much in fashion among French youths of both European and non-European origin.
Quite tellingly, its main leader is a French-Cameroonian performer, Dieudonné M'Bala M'Bala, the creator of the "quenelle", an inverted Nazi salute.
"All of sudden, we realised there might literally be no future for us," a young Parisian couple say. They will move to Tel Aviv in August.
Chief Rabbi Korsia, who, as a young army chaplain, developed a personal friendship with the then president Jacques Chirac, is convinced the French-Jewish symbiosis initiated under Napoleon will endure. As a rule, Chief Rabbis do not have much religious or political influence on French Jewry - except in times of crisis. That may turn out to be the case with Rabbi Korsia.