Frozen nearly two miles below the surface of the Antarctic Ice sheet are clues to our climate history and our future.
Six years ago researchers at the National Science Foundation started drilling through the miles-thick ice at the West Antarctic Ice Sheet divide on a mission to learn more about how changes in the concentration of atmospheric greenhouse gases have influenced climate over time.
Last week, the team completed drilling their main ice core to a depth of 3,331 meters ( just under two miles). It is the deepest ice core ever drilled in Antarctica and the second deepest in history.
By studying the chemical makeup of the ice and the particles trapped within it, researchers hope to gain a stronger understanding of what air temperatures, ocean temperatures and particle concentrations were like at various points in history. From this knowledge scientists can better predict future climate changes from human-caused greenhouse gas emissions.
Extracting layers of climate history
Ice at the bottom of these cores fell as snow approximately 100,000 years ago. Over time, the layers of snow compress and freeze as ice, trapping atmospheric particles, gases, dust and air bubbles. These ice layers build up strata and can be counted and studied like rings on a tree. The deeper the ice, the further back in time measurements can be made.
Previous research using ice cores has focused on determining historical surface air temperatures and ocean temperatures. This project is different. The Antarctic WAIS project is specifically investigating the time differences between past changes in greenhouse gas concentration and when the resulting temperature shifted. By understanding these offsets, the teams hope to determine the role that changes in ocean circulation had in the release of carbon dioxide from the ocean and how an increase in carbon dioxide in the atmosphere warms the planet.
“Previous ice cores have shown that the current level of greenhouse gases is greater now than at any time during the last 650,000 years, and that concentrations today are increasing at the fastest rate. This increase is caused by human activity and is forcing the climate into a configuration that no human has ever experienced.” – Kendrick Taylor, chief scientist for the WAIS Divide Ice Core Project
The 13cm round ice cores are to be divided into more than 3,000 1-metre long segments and shipped to a team of 27 researchers across the United States who will study them and distill findings over the next two years.
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