When it comes to understanding what鈥檚 happening with our climate, scientists have an abundance of hard cold facts at their fingertips in the form of ice cores that are cut, organized, and stored at the National Ice Core Facility located at the Denver Federal Center. Assistant Curator Richard Nunn refers to the ice cores as 鈥渁ncient time capsules.鈥�
鈥淭hey are the best record of what our Earth鈥檚 climate has been doing over the last 850,000 years,鈥� he says.
鈥淚f we want to understand what the climate鈥檚 doing now with human activity, the best way to answer that is to really understand the natural cycles that our climate goes through, and ice cores give us that picture better than anything else on the planet.鈥�
Scientists travel to some of the harshest and coldest places on Earth to collect ice cores, which are typically drilled 200 to 300 meters deep into the ice, though some extend as far as two miles.
Once extracted, the cores are cut into smaller segments for easier handling, carefully packaged, and transported to two large freezers at the National Science Foundation Ice Core Facility in Lakewood, Colo.
鈥淎bout 60 percent of our collection comes from Antarctica, and about 20-some percent comes from Greenland. Then we have a small smattering of cores from alpine glaciers around the world鈥� says Nunn.
鈥淲e are the largest collection of ice cores in the world. We have close to 25,000 meters worth of ice stored in our facility right now.鈥�
The facility has an ice-cold workspace for scientists to cut and collect samples they will then take back to their universities for analysis. A second freezer area, kept at an even colder temperature, is used to shelve and store the ice cores.
While demonstrating how to cut an ice sample, Assistant Curator Richard Nunn compared the process to slicing butter.
鈥淭here鈥檚 very little resistance. It鈥檚 not like cutting wood or metal or anything. It鈥檚 fragile, so we have to be careful. But it cuts very easily,鈥� he says.
Eric Steig, a geochemist from the Earth and Space Sciences department at the University of Washington in Seattle, recently visited the National Science Foundation Ice Core Facility to cut thousands of samples from an ice core drilled on Mount Waddington, the second-highest peak in British Columbia.
鈥淭he main thing we鈥檙e working on right now is measurements of the isotopic concentration of water, and this is the ratio of heavy to light oxygen in the oxygen in the H鈧侽, in the water. And we are interested in that because it gives you an imperfect but still really useful measure of temperature. So we鈥檙e getting a record of temperature through time,鈥� says Steig.
When snow falls in the polar and glacial regions, it accumulates over time and becomes compacted into large ice sheets. These ice sheets preserve vital information, including trapped atmospheric gases, stable isotopes of water molecules, and ancient dust.
鈥淲e can get an ice core that has records from modern times, all the way back to 850,000 years ago. And we can use that to recreate what was going on in the atmosphere and how things like carbon dioxide and methane (our major greenhouse gases), have fluctuated over time naturally, and how our temperatures have also changed as we鈥檝e gone in and out of these glacial cycles,鈥� says Nunn.
Richard Nunn, who has worked at the Ice Core Facility since 2010, says his work is fascinating but has its challenges.
鈥淧robably the most challenging aspect is that we have to work in extremely cold temperatures. And even with all the proper gear, it can be not always pleasant. Some days are better than others. But we work anywhere from -24 degrees Celsius, to -40 degrees Celsius, depending on which part of the freezer I鈥檓 in,鈥� he says.
Earth goes through natural cycles of cooling and warming, but Nunn says the ice cores reveal concerning information about the rapidly rising greenhouse gases and their effect on climate change.
Human-caused climate change
鈥淲hen we look at this and talk about what鈥檚 happening today, a better phrase would be 鈥榓nthropogenic climate change,鈥� or 鈥榟uman-caused climate change.鈥� And that鈥檚 what we鈥檙e concerned about in the modern times. What we see today, after the industrial revolution, is CO2 levels spiking to currently we鈥檙e at 425 parts per million,鈥� he says.
鈥淲e are well above where we鈥檝e ever seen in the CO2 levels during the entire ice core record. And the rate at which we got there is easily ten times faster than anything we鈥檝e ever seen in the natural cycle. What we鈥檙e seeing now is better described as 鈥榬apid climate change.鈥� We鈥檙e taking 2,000 years worth of this and condensing it into a couple centuries.鈥�
When it comes to climate skeptics, Richard Nunn has this to say:
鈥淚t sounds rote because I鈥檝e said it so many times, but look at the raw science. If you can actually just spend a little bit of time to understand the nature of how our climate naturally changes, and then see what鈥檚 happening now, it鈥檚 pretty evident that we鈥檙e having a big impact. The planet itself is, on average, warming.鈥�
In addition to welcoming scientists from around the country and world, members of the public can also visit the ice core facility.
This material is based upon work supported by the National Science Foundation under Grant No. 2041950. Copyright 2024 Rocky Mountain Community Radio.
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