Travels with 6thExtinctionLab Mobile Unit -Time Capsules in an Iceberg
The 6^(th)ExtinctionLab mobile unit has traveled extensively in the last year visiting all the lower 48 US States and 8 Canadian provinces. Most memorable location was northern Newfoundland where the Vikings had established a seasonal colony. Archaeological evidence now places Norse activity at L’Anse aux Meadows very precisely at AD 1021. I Had the opportunity to see huge icebergs from Greenland just offshore and I was able to drink meltwater from ice that melted from ice chunks that had broken off the ‘bergs and drifted to shore. Compressed gasses in the melting ice rose in my glass as I drank the water.
Greenland glacier ice is formed when successive layers of snow accumulate, are compressed, and eventually become solid glacier ice. Icebergs calved from Greenland can contain ice that is tens of thousands of years old.
I may have been drinking water that had been frozen in a Greenland glacier for roughly 10,000 years or potentially many tens of thousands of years before the iceberg reached Newfoundland.
The bubbles were not ordinary bubbles of air that had recently become trapped in the iceberg. They originated from atmospheric air that was trapped as snowfall was compressed into glacier ice. Studies of actual Greenland icebergs have measured gas bubbles at pressures of 4–5 atmospheres on average, with some reaching 20 atmospheres. As the ice melts, those pressurized bubbles expand and burst, producing the little fizzing effect I noticed.
The trapped gas can preserve information about the atmosphere when the snow was originally being converted into ice. Ice-core studies use exactly this phenomenon to reconstruct ancient atmospheric composition, including CO₂ and methane. So, in a very literal sense, when I drank that meltwater I may have been drinking water from ancient Greenland snowfall, while simultaneously watching ancient atmospheric air escape from the ice. Those bubbles are essentially tiny time capsules of Earth's atmosphere.