Scientists can study the Earth’s current ongoings by observing how things are going right now. However, to study the past requires different approaches. Similar to tree rings or sediment layers, ice holds a lot of interesting information. Climate scientists that are attempting to better understand Earth’s climate history often find themselves looking for clues buried deep down. Why are scientists digging up old ice? Listen to this Question Your World radio report produced by the Science Museum of Virginia to find out.
As snow freezes and accumulates at the polar regions of our Earth, it also traps atmospheric information in tiny little bubbles. Over time the layers of snow add up and get squished into glacial ice. These trapped layers show the seasonal cycle of the annual winter time freeze and the summer time snow melt throughout the years.
Using these layers that are literally frozen throughout time, scientists can go back and study the history of Earth’s atmosphere with these layers similar to studying a tree using tree ring. Unlike tree rings, these layers are more like a stack of flapjacks with the oldest stuff at the bottom.
Places in Antarctica have accumulated millions of years of ice layers and in turn are holding millions of years of atmospheric information. This makes these thick ice sheets act kind of like a time capsule of climate information. As snowy days of the past fell to the ground they took with them a little bit of the Earth’s climate history with them and were preserved in layers over time just waiting for someone to come along and read this part of the story of the Earth.
By drilling into those ice sheets scientists can study Earth’s ancient climate. Researchers have dug into these ice sheets and been able to study the last 800,000 years of Earth’s continuous climate history*. The results from that study show that atmospheric levels of heat trapping gases like Carbon Dioxide have never changed faster or been higher than what they are right now.
And now for some breaking news! An international group of ice core scientists have just discovered an area of Antarctica that has preserved ice that is about 2.7 Million years old! The research involved with this 2.7 million year ice is still going and thus no published journals are released yet. However, the Initial results suggest that heat trapping gases were nowhere near the levels that we’re currently experiencing, even over 2 million years ago.
A very real reminder of the impacts of how we humans can alter the natural world around us and like anything else you want to learn more about, you really do have to get to the bottom of it especially if its ice.
* Paper for 800,000 year record: Lüthi, D., M. Le Floch, B. Bereiter, T. Blunier, J.-M. Barnola, et al. 2008. High-resolution carbon dioxide concentration record 650,000-800,000 years before present. Nature 453: 379-382. doi:10.1038/nature06949.