CHAMONIX, France — Bright sunshine and mostly brown slopes welcomed skiers to the Chamonix-Mont-Blanc Valley just before New Year’s Eve, a sight that hardly came as a shock.
Across France, December 2015 was already on track to be the warmest since 1900, a fact since confirmed by Météo France, the national weather service.
The toll of global warming on Alpine ski resorts has already been well documented. A 2006-7 report by the Organization for Economic Cooperation and Development, which landed in the middle of another warm winter, had an immediate impact. In Germany, Der Spiegel warned of “Snow Cannons Against the Apocalypse,” and The Daily Telegraph in Britain declared, “Global Warming Could Spell Ruin for Alps.”
The facts were bad enough without the hyperbole: By 2005, temperatures had increased three times the global average. According to one forecast, 75 percent of Switzerland’s glaciers will disappear by 2050.
Of the 666 Alpine ski resorts examined by O.E.C.D. researchers, only 404 will be able to rely on natural snow once temperatures rise by 2 degrees Celsius, or 3.6 degrees Fahrenheit, from 2006-7 levels, which could happen as soon as 2050. The losers will be resorts on low-lying slopes.
The reaction to the report was described as “mindblowing” by its editor, Shardul Agrawala, head of the organization’s environment and economic integration division. “Since then, every time there is a warm winter, it bubbles up again and there is new interest,” he said.
Many of the report’s findings have since been taken into account by governments of the Alpine countries as well as by the ski industry.
“What is happening is largely related to more reactive measures,” Mr. Agrawala said. He noted an “exponential” increase in the reliance on snow-making machines, the development of upper reaches of ski areas, more grooming of slopes, and a turn toward shaded, north-facing slopes, where snow — when there is any — lingers for longer.
“It is about how much you can squeeze with existing snow, or supplement with snow making, but there may be limits to both,” he said.
Snow — “white gold,” they call it here — did fall over much of the French Alps after the New Year, just as the crucial holiday season was coming to an end.
Here at Chamonix-Mont-Blanc, one of France’s highest ski resorts, 42 percent of the region’s 507 ski runs were closed during the holidays, according to Fabienne Martinez, communications director for the Compagnie du Mont-Blanc, which runs the resort.
Up until the late snowfall, skiing was concentrated on the upper runs of the north-facing Grands Montets slope, making for crowded and icy skiing.
But at least there was some snow. At some nearby low-lying resorts, helicopters were spotted dropping buckets of fresh snow to replace the fast melting slush on the baby slopes below.
Even Chamonix had to come up with ways to keep its visitors busy — petting zoos for children, air rifle contests for adults, paragliding for the brave.
It was saved by the unique gold mine on its doorstep — Mont Blanc, Western Europe’s highest mountain, which can be best viewed from a ride up to the nearby peak, the 12,600-foot-high Aiguille du Midi, and other scenic tours that don’t involve skiing, but are included in the region’s unlimited ski pass, together with the local swimming pool, ice skating rink and museum.
These added attractions helped increase the sales of unlimited daily ski passes 15 percent and sent the number of rides up to the Aiguille du Midi soaring 65 percent compared with last year, Ms. Martinez said.
France’s $2 billion ski industry is the largest of the five major Alpine nations. French mountains are also a major employer, reportedly the country’s biggest during the four winter months that traditionally make up the Alpine skiing season.
Given the importance and the fragility of winter tourism, French ski resorts are scrambling not only to make up for the snow deficit, but also to keep visitors entertained in a world where they can always jump on a plane and go to a beach.
The days of skiing in the Alps are not numbered, said Mr. Agrawala, who has skied the mountains himself. “It will just be more concentrated at higher altitudes,” he predicted. “There will be winners and losers.”
Because of an editing error, an earlier version of this article misstated the context of a comment by Shardul Agrawala of the Organization for Economic Cooperation and Development, editor of a climate change report on the phenomenon. He said the reaction to the report was “mind-blowing,” not the report itself.