Many years ago I did a master’s degree thesis on what we can learn by studying ice core data. To do this, I looked at a core taken from Mt. Rainier and another taken from Alaska.
Those ice cores were taken in a place where it never gets warm enough for the ice and snow to melt. In the winter it snows, and the snow doesn’t melt but gets buried by the next winter snow. In the summer the snow from the previous winter gets dirty on top. Dust, insects, pollen, and the remains of plants and animals that died on the ice accumulate and are buried by the next winter’s snow. This happens year after year, so each summer leaves a line in the snow. Looking at these lines with a stereoscope I could count how many summers had passed and what lived during that summer.
Since my studies when I was a graduate student at Notre Dame, techniques for getting ice core data have improved. We can now get deeper cores in places like Antarctica and Greenland. Also, we now have tools which can measure the composition and abundance of atmospheric gases dissolved in the ice. We now have drill cores that go down over a mile. In 1984, scientists took a core at Vostok in the Antarctic that was 6,560 feet and contained about 420,000 summers. That means we can analyze the gases in Earth’s atmosphere for every year going back over 400,000 years.
Scientists then compared the carbon dioxide content of the atmosphere and the average temperature for each location. They could see that when the carbon dioxide content went up, the average temperature also went up. Global warming is not a new thing, but how much human activity has affected the current warming is still unknown. What other factors might be involved is still pretty much conjecture.
Already we see some changes that the warming is producing with the melting of ice sheets and altered weather patterns. Not all of the changes are bad. Some places that have had a drought for a very long time are getting much-needed moisture. Fortunately, these changes are slow so that we can adapt. We can see the design of Earth to allow life to exist more clearly as the ice core data reveals its history.
–John N. Clayton © 2019
Data from Saturday Evening Post, January/February 2019, page 44.