Either way, the heart of any condemned man couldn't help but be momentarily lifted by the spectacular explosion of Oxford Streets Christmas lights snaking eastwards towards Centerpoint.

This years lights were turned on by All Saints, and then serenaded by Jordan and Peter Andre - a couple who have been surrounded by cartoon extravagance since Jordan lifted her wedding dress to release half a dozen doves. And the lights look touched by the very same hand of stylized romance grown in influence to an urban scale.

The street has been reconfigured as a two-mile long ballroom by a canopy of chandeliers. The large chandeliers - around 3 metres in diameter - use a mesh of small lights to define their form like a point cloud render. The sparkle of the lights simulates the effect of crystal. At their lower rim, they sprout a crown of curved arms holding electric candles. These details - along with their accurate shape - provide significant realistic detail to suggest that there really are heavy, elaborate chandeliers hanging above the tarmac. A series of smaller chandeliers are formed with frames studded with LEDs bent into elaborate outlines. Both are set amongst mesh swags of golden sparkles. The chandeliers glow with a strange almost ultraviolet blue that suggests they are surrounded by a misty haze.

At first glance, the chandeliers possess that contemporary design trope of historical reference made through contemporary means: The economy of representation, the transfer of material and technology are both present. However, the blank, empty nihilism of designer irony is replaced by a sentimental cuteness that makes a direct appeal to ones gooey soft centre.

The transformation of objects from light reflecting to light emitting is part of the displays surreal wonder. Arranged in bands with variations in size and number creating a repeating rhythm, the display creates a dense canopy when viewed along the length of the street. It is surprising how something so light and ephemeral takes its civic role so seriously.

The trees that are unfortunate enough to grow along Oxford Street have been hung with the strange fruit of golden baubles and cloaked with sparkling light. Behind the trees, shop frontages assume another layer of decoration. The entire street has become a strip of pulsing lights. Electricity constantly chases and blinks in an unsettling, nervous shuddering anticipation of consumption. Imagine a romantic winterscape plotted by an ECG monitor.

This nervous excitement and titillating expectation is heightened by the shop dummies who line the street like wanton Caryatids in cut-price party dresses. Their promiscuous poses - somewhere between Mannequin and Eyes Wide Shut - hint at office party decadence as yet undreamed.

The effect of the decoration turns the street into a tunnel of festivity. Entrances to shops become openings into caverns of festivity - the cave mouths lined with ridges of faux fir and cascades of blue-white lights. It is as though the surface of the street folds in on itself. One could imagine the inside-outside flow being mapped like a nativity version of Giambattista Nollis plan of Renaissance Rome that showed interior spaces of buildings as part of exterior public space. Though here, the street is dressed as interior, the interiors as exteriors. Roadway becomes becomes floor, exterior walls become interior, sky becomes ceiling.

More inversion: looking into shop windows from outside feels like looking out over a landscape: At Selfridges a topiary night scene, at the Disney Store a polystyrene snow scene, at Adidas, pale and misty silver birch forests.

Interior and exterior tumble together in confusion. Hard-edged buildings seem to vanish as brightness and darkness short-circuit my eyes rods and cones. Just as a moth flies toward a flame because it perceives greater darkness behind the light, stone facades fade and the infinite space of the night sky becomes solid black behind the blinking lights. My Travelcard might say 'Zone 1' - my eyes seeing something else.

There is so much snow-covered landscape, and it's all been arranged by the first week of November. This artificial winter scenography is not just incredible in its intricacy and depth, but it's also at ironic odds with 'real' winter.

Climate change research shows autumn and spring are eroding either end of winter. Many European plants flower a week earlier than they did in the 1950s and lose their leaves 5 days later. Biologists report that many birds and frogs are breeding earlier in the season. The spring ice thaw in the Northern Hemisphere occurs 9 days earlier than it did 150 years ago, and the autumn freeze now typically starts 10 days later.

North of forty degrees north latitude, the growing season for vegetation has increased by several days. The ice cap is thinning. The artic is becoming greener and could become ice-free during summer months by 2060. Father Christmas might think about trading in his sled for a 4x4.

Winter is shrinking. Meanwhile, we extend our artificial version in a frenzy of decoration and experiences. Harrods opens its Christmas shop in August, mince pies are on the supermarket shelves in September, and Christmas singles are plotted in spring. The festive season creeps across the calendar like an icy inkblot.

Maybe it's because there are fewer real snowflakes that we feel the need to manufacture decorative ones. Perhaps it's guilt and fear made palpable through tinsel and fiber optics. An attempt to salve a loss that we can't quite yet comprehend. Perhaps it is preparation for a future where winter simply doesn't occur naturally anymore.

In the Alps, average temperatures have risen by up to 3 degrees over the last century during the winter months at 1800 meters. Lack of snowfall in some regions has caused problems to the skiing industry. Even the snow canons, which blast artificially created snow over the pistes to augment natural precipitation can't fix it when temperatures are above zero. Winter wonderlands are starting to look very different.

Ironically, our representations of these wintry scenes become stronger, denser and more hysterical just as their reality is threatened.

Each winter you can skate - just as you can in many other locations - on a temporary ice rink at Somerset House. What's different in this case is that it is just yards away from the old banks of the Thames. Since the construction of the new London Bridge and the Embankment, the rivers increased speed has stopped it freezing over. 200 years previously, this stretch of the Thames was the site of the Frost Fairs, which took place on the frozen river. The idea still persists as a simulated echo as you skate across ice frozen by a grid of pipes pumped through with brinewater cooled to -9 degrees by evaporating Freon. You might call this 'architecture of the sureally tempered environment'.

Landscapes are as much about imagination as they are geography. The landscapes we draw and make of winter are not illustrations but a fictionalized view of the world. These winter wonderland scenes freeze moments when the world looks new and fresh: coated with overnight snow; icicles glistening in the winter sun; the crystalline patterns of snowflakes. That freshness is a brief glimpse of what we imagine nature could be, or once was. The myths of Eden and Arcadia served previous generations as visions of the world before the fall. Frosty the Snowman does the same thing for us. Nativity scenes, shop window displays, and seasonal blockbusters provide a static point to fix our gaze upon in an attempt to avoid motion sickness as the environment shifts and swells in flux.

Simulations of future climate change are running on the computer systems of university research departments. Equations represent the physical processes of the climate, calculations chart possible future versions of the earth. The United Nations' Intergovernmental Panel on Climate Change projects that global temperatures will rise an additional 1.6 to 5.5 degrees Celsius by the century's end. What these winters will look like is probably not part of these simulations. What new meanings will we attach to winter? What new significance will it gain?

Perhaps these super scaled festive installations will escape their manmade habitats and begin to fill the voids of winter-depleted landscapes. Perhaps we will see forests of white fiber optic trees planted over the slopes of Bavarian mountains, colour-cycling through the warm nights. Or perhaps sparkling neon snowflakes will be suspended in flocks over a scorched North Pole. Maybe armies of set-dressers will squirting spray-on-snow over pine needles. Perhaps these installations will become an artificial Narnia - permanent monuments to a season that is disappearing.

Back on Oxford Street, I'm mistaking the jingle of Hare Krishnas for sleigh bells, but I've made it to Tottenham Court Road. Below-ground infrastructure has never been quite so appealing. Heading down into the tube station is escape from the shrill and jittery sci-fi faux-landscape into the dull embrace of the earth. My advice? Don't re-surface till January the 6th.