This was originally published in the Kildare Nationalist newspaper. 

Across the world people celebrate Christmas – or some related Western holiday that has been caught in Christmas’ cultural orbit – with a set of familiar symbols. In California and Calais alike stores sell cards of snowy landscapes, and paint frosted evergreens on their windows in Florida and Florence. We all listen to carols about snowmen and reindeer, holly and mistletoe, stocking-caps and logs blazing on a fire. We watch White Christmas, and feel disappointed when we don’t get one.

Yet few people question why we embrace such relentlessly Nordic imagery. Most of us are not Saami and have never seen a real sleigh or reindeer, nor do holly and mistletoe grow in most of our regions.

Generations of Hollywood films have conditioned us to expect snowbound Christmases, even though they are no longer the norm for Missouri (Meet Me in St. Louis), modern London (Love, Actually), or most of the other cities where such movies are set.

I realised I did the same thing yesterday; when I wanted to post a photo on Christmas Eve, I took one from a few years ago, when we had an unusual snowfall. It was the photo that looked “Christmasy” – the others would look a bit unseasonal to our eyes.

Nor, of course, do any Nordic images have anything to do with the Middle East where Jesus lived, even though most of us grew up putting stable-and-manger figurines in a little snow-bound setting.

In fact, many of our White Christmas images seem to come from one original source, the story that has been repeated so often over the years – A Christmas Carol. Almost every inhabitant of the First World knows the name Ebenezer Scrooge, of course, but few of us realise how many of our holiday customs – Santa and Christmas trees, carolling and family gatherings – were influenced, if not necessarily invented, by that book.

When The Girl and I read the story, however, I was impressed by how much attention Dickens paid to the weather. On almost every page, it seems, he has a new description of chilled bones, nipped noses, frosted fields, iced-over pools and paths trodden through snow. Characters see their own breath indoors, and when Scrooge looks outside, he must scrub away the layers of frost on the window – inside.

Early on Dickens writes:

Meanwhile the fog and darkness thickened so, that people ran about with flaring links, proffering their services to go before horses in carriages and conduct them on their way. The ancient tower of a church … struck the hours and quarters in the clouds with tremulous vibrations afterwards, as if its teeth were chattering in its frozen head up there. The cold became intense. 

In the main street, at the corner of the court, some labourers were repairing the gas-pipes, and had lighted a great fire in a brazier, round which a party of ragged men and boys were gathered, warming their hands and winking their eyes before the blaze in rapture. The water-plug, being left in solitude, its overflowings silently congealed, and turned to misanthropic ice. 

Dickens wasn’t making up such scenes; he was a child when London saw the last of the Frost Fairs, markets and gatherings held on the frozen surface of the Thames River. His writings came at the end of the Little Ice Age, a period of two or three centuries when the global climate dipped. During this time Dutch artists painted images of skating on canals in April, invading armies easily crossed from Sweden to Denmark across their oceanic straits, and famine was common across Europe. Our Christmas images come from a time and place when the climate was genuinely different.

Since then, in the late 19th century to the early 21st, places like London have seen far less snow and ice at Christmas, and Ireland less still. As the climate grows hotter in the decades ahead, we are likely to see ever-warmer winters and fewer White Christmases still, unless the melting Arctic ice disrupts the Atlantic current that keeps Europe mild.

Most interesting, though, is a possible reason why the climate dipped in the few hundred years after 1600; Europeans colonizing the Americas. Columbus and other Spaniards brought disease that wiped out 90 per cent of the local population, the theory goes, which meant millions of farmers no longer farming. Billions of trees grew up from what had once been crop fields, and each of those trees contained tonnes of carbon that were sucked out of the atmosphere.

The rise and fall of carbon dioxide in the atmosphere is the main factor that controls the climate; when more carbon dioxide gets pumped into the air, as we are doing now, the world gets hotter, and when more gets sucked out of the air, as happened in the 1500s and 1600s, the world sees colder winters that lasted into Dickens’ time.

Among other things, this tells us what we need to do to stop the runaway climate change scientists predict for the rest of the century. Turning more fields into trees again – something simple and within the power of most of us – would not risk even a little Ice Age at this point, and it could help our descendants one day see White Christmases again.