The warmest November-December since records began has put Russia's fearsome winter on the back foot.

Mushrooms are sprouting outside Moscow, bears are unable to hibernate, and Bilik, who looks older than her 53 years, is having trouble attracting customers to her stall in the city centre, where she hawks thick socks, slippers and fake fur vests.

"When it's cold, they buy, when it's warm they don't," she says, gold teeth flashing against the gloomy, almost permanent twilight that has oppressed sunless -- and snowless -- Moscow for several weeks.

Gennady Yeliseyev, deputy director of the state's weather service, the Gidrometeocentre, said that since November 20 Russia has experienced the warmest temperatures since records began in the 1870s.

"Average temperatures for the first 10 days of December are minus five degrees Celsius (23 degrees Fahrenheit) and the current abnormalities range as high as plus 10 degrees Celsius (50 Fahrenheit)," he said. "This is the weather we'd normally have in late October."

Scientists here believe Russia has fallen victim to the phenomenon of global warming already blamed for turning European ski resorts into grass meadows, driving exotic fish to British coasts, and whipping up ever more destructive natural disasters.

"The obvious explanation is that very powerful cyclones are forming over the north Atlantic and moving toward the Barents Sea," Yeliseyev said. "But there is also general change to a warmer climate and you cannot deny a link to the greenhouse effect."

Leading weather expert Alexander Bedritskovo said that climate change in Russia is "reality."

Although temperatures will inevitably drop -- wet snow could start falling in Moscow this week, according to forecasters -- weird things are already happening in a country synonymous with harsh, long winters.

In far away Siberia, the ice has begun to melt and break up along a 155-mile (250-kilometre) stretch of the great river Yenise.

At the Moscow zoo, warm temperatures are prompting birds into the love making usually reserved for spring, while the brown bear couple Mushir and Rosa are grumpily insomniac as they wait for snow and hibernation.

"His mood is worse, but she's calmer," zoo spokeswoman Yelena Mendosa said. "She's a female and she deals with his moodiness because she loves him."

Human inhabitants of the capital find the lack of snow a mixed blessing.

"Of course I'm waiting impatiently for winter -- I'm a Russian!" exclaimed economics teacher Nina Babrova, 55, resplendent in one of the few fur hats visible on Moscow's streets.

But joining the huddle of smokers on the pavement outside Soyuz Bank, Vladimir Sharikadze, 20, crossed his fingers that the milder weather would last. "This is great for us smokers. Maybe when winter comes we'll have to give up."

Yekaterina, a 20-year-old student, was also making the most of the phony winter.

While most women are now wrapped in trousers and boots, her legs were clad in nothing but thin tights and a skirt that came well above the knees. "This is easy," she said.

And will she be that brave when the traditional Russian freeze finally strikes? She laughed under her white wool hat.

"You must be crazy!"

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