The smell of ice

Welcome to Back of the Napkin, musings from Serviette for the cultured world.

The question “What does ice smell like?” sounds, at first, like the sort of thing one asks after too much Sancerre. Ice itself has little to offer the nose in the conventional sense. But the experience of breathing in cold air is emphatic, and many have tried to discern its olfactive qualities (Serviette’s perfumer, included).

This is the funny thing about ice: its smell is often less about odor than evidence. In paleo sea ice research, scientists reconstruct ancient frozen environments through biomarkers left behind by marine diatoms (little algae with the manners of archivists). Highly branched isoprenoid alkenes, or HBIs, can indicate the presence of past sea ice, while other compounds suggest open water after seasonal melting. Imagine the planet leaving faint oily receipts in sediment and ice cores, then asking a gas chromatograph to read them back centuries later.

In Frisson D’Hiver, that icy effect is constructed through materials that stimulate cold-sensitive TRPM8 receptors in the nasal passages, much as menthol and camphor do—users of Vick’s Vapo Rub or Vapo inhaler sticks will understand the sensation. These receptors usually respond when we inhale cool air, but certain materials can prod them without an actual temperature change. The brain, obliging fool that it is, interprets this as increased airflow, even when the nose has not physically become less congested. Spoiler: those medicines don’t actually do anything for congestion.

Frisson D’Hiver asks a less solemn but adjacent question: can a perfume make the nose believe it has stepped into winter? One reviewer perfectly captured Frisson D’Hiver’s mineralic chilliness, writing, “Everything is lightly dusted with ice shavings, cooled down, slowed down and projecting their scents at a very subtle sound level and encased in perfectly spherical floating water bubbles.”

Ice isn’t just a fascination for perfumers. On the Moon, NASA researchers preparing for future Artemis sample returns have been developing methods for what is called cold curation: preserving volatile-bearing lunar samples, especially those collected near polar craters or permanently shadowed regions, with as little alteration as possible. Scientists study simulants containing volatile analytes such as methanol, ammonia, hydrogen sulfide, ethanol, and isopropanol, using GC/MS to separate, identify, and quantify headspace gases. In other words, the Moon may have a smell, but only if one is very careful not to ruin it by bringing it home.

There is a pleasing procedural drama to this research. Sea ice cores are cut, melted under controlled conditions, filtered, freeze-dried, ground, treated, extracted, purified, and finally analyzed through machinery. Taste, too, is sometimes built this way: by detecting small traces, following them through time, and deciding they mean something. A fragrance with an ice accord does a similar thing on the skin, except the climate event is happening on your wrist.

Thanks, as ever, for reading.