The Ice Harvesting Industry: Cutting and Exporting Winter Cold

For a period of roughly a century, from the early nineteenth century to the early twentieth, one of Norway's exports to the rest of Europe was winter itself, in the most literal sense: blocks of ice, cut from frozen lakes, packed in sawdust and shipped abroad to be used in the days before mechanical refrigeration existed. This industry, almost entirely forgotten today, was a significant part of the economy of the lakes and waterways around Oslo for several generations.

The Demand for Natural Ice

Before the development of practical mechanical refrigeration in the late nineteenth century, the only way to keep food, drink and other perishable goods cold was with ice — and ice, in the quantities required by growing nineteenth-century cities, had to come from somewhere that froze reliably and predictably each winter. Britain's own winters were too mild and unreliable to produce ice at the scale its growing urban population, breweries, fishmongers and households required. Norway's lakes, by contrast, froze to a thickness of half a metre or more with dependable regularity each winter, producing a resource that could be harvested, stored and shipped to markets where natural ice could not be reliably produced locally.

The lakes around Oslo — including Maridalsvannet, the lake that today serves as the city's drinking water reservoir, and Bogstadvannet to the west of the city — were among the sites where this harvesting took place at scale, their proximity to the harbour making the logistics of export practical.

The Harvesting Process

Ice harvesting was a substantial seasonal industry employing significant numbers of workers each winter. Once lake ice reached sufficient thickness — typically requiring several weeks of sustained cold — workers would mark out a grid pattern on the ice surface and cut along these lines using large hand saws, and later mechanised saws powered by steam or, eventually, internal combustion engines. The cut blocks, often weighing as much as a hundred kilograms or more, were floated to the shore along channels cut in the ice, then hauled out using horses, ramps and pulley systems and transported to storage.

Storage was as critical as harvesting. Ice houses — large, heavily insulated buildings, often partially below ground, with walls and ceiling cavities packed with sawdust or other insulating material — could keep harvested ice frozen for many months, allowing it to be shipped through spring and summer when demand in importing countries was highest and when no fresh ice could be produced anywhere in Northern Europe.

Export and the London Ice Trade

Norwegian lake ice was shipped in large quantities to Britain, Germany and other European markets, where it supplied the ice trade that kept breweries, fishmongers, butchers and, increasingly, households supplied with the means to preserve perishable goods. London in particular was a major destination for Norwegian ice through much of the nineteenth century, with specialised ice warehouses built at London docks specifically to receive and store cargoes of Norwegian ice for distribution across the city.

The trade was sufficiently significant that "Norwegian ice" became a recognised commodity category in its own right in import markets, distinct from ice harvested from sources closer to the destination markets, such as ice imported from the United States, with which Norwegian ice competed directly on the basis of quality, reliability of supply and price.

The End of an Industry

The natural ice trade declined rapidly in the early twentieth century as mechanical refrigeration — initially industrial-scale refrigeration plants, and later domestic refrigerators — eliminated the need for natural ice almost entirely within the space of a few decades. An industry that had employed thousands of seasonal workers across Norway's lake districts, and that had represented a meaningful export earner for the country, simply ceased to exist as the technology that had created the demand for it was superseded.

Little physical evidence of the ice harvesting industry survives in or around Oslo today. The ice houses, built for a single specific purpose that no longer existed once refrigeration arrived, were repurposed or demolished. What remains is largely documentary — photographs of workers cutting grid patterns into the ice of Maridalsvannet, ledgers recording shipments to London and Hamburg, and the occasional place name or local memory that hints at an industry that, for a while, made the Norwegian winter itself a tradeable commodity.