Newswise — Scientists at South Dakota State University analyzed a half-mile slice of Western Antarctica ice core to help determine that climate change begins in the Arctic and moves southward, according to chemistry professor Jihong Cole-Dai of the SDSU Ice Core and Environmental Chemistry Lab.

Since 2006, the SDSU research team have been part of a National Science Foundation project to uncover the secrets within an ice core dating 68,000 years. Researchers from more than 20 university and national laboratories helped retrieve and analyze more than 2 miles of ice core from the Western Antarctica Ice Sheet Divide. The drilling was completed in 2012.

“The accuracy of the dating was absolutely critical for this project,” pointed out Cole-Dai, whose team analyzed ice dating 6,000 years. Over the last eight years, two master’s students, three doctoral students and one postdoctoral scientist have worked on the project.

By measuring trace chemicals, the researchers create a data set that essentially counts the years in the core, he explained. “We created a map like a tree stump where you can see the rings and figure out how old the tree is at any stage of growth.”

The team developed a specialized instrument to accomplish the work in less than three years. “That’s a big improvement,” Cole-Dai noted. If done manually, the work would take 10 years or more. The Western Antarctica ice core results were compared to those of an ice core from Greenland in the Arctic to show that when the Earth came out of the last ice age warming began in the North Atlantic and spread southward over the next 200 years. The findings were published in the April 30 edition of Nature, an international weekly journal of science.

“Our main contribution was to generate a data set that allowed the whole project to figure out exactly the age at which important events occurred,” Cole-Dai said. “If researchers saw a bit of warm-up, they needed to know what year that was.”

To accurately track time, the researchers cut the core into samples the size of ice cubes, Cole-Dai explained. “That translates to thousands and thousands of samples.”

The team analyzed what is known as the brittle ice zone, Cole-Dai explained. “It was brittle to the touch and this portion had more fractures. It was the most challenging part in terms of analysis.”

Their analysis determined the date of each cube within a few years, he noted. “Other people have tried with other ice cores but couldn’t be that precise about age. We are the first science project to figure that out.”

Scientists want to know the signs and symptoms should global warming lead to a change in the global climate, Cole-Dai explained. “By studying these things in the past in a very detailed, systemic way, we can do a better job of forecasting the future.”

About Ice Core and Environmental Chemistry LabSDSU students and faculty in the Ice Core and Environmental Chemistry Lab (ICECL) conduct basic research in atmospheric chemistry and on the global atmospheric environment and climate using snow and ice core samples from the polar regions of Earth. ICECL is a part of the research program of SDSU Department of Chemistry and Biochemistry.

About South Dakota State UniversityFounded in 1881, South Dakota State University is the state’s Morrill Act land-grant institution as well as its largest, most comprehensive school of higher education. SDSU confers degrees from eight different colleges representing more than 175 majors, minors and specializations. The institution also offers 32 master’s degree programs, 15 Ph.D. and two professional programs. The work of the university is carried out on a residential campus in Brookings, at sites in Sioux Falls, Pierre and Rapid City, and through Cooperative Extension offices and Agricultural Experiment Station research sites across the state.