The timing and duration of historical climate changes have been debated by scientists for years. Ice core records, though, can offer a way for scientists to study glacial-interglacial cycles.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/ice-cores-may-reveal-historical-climate-changes-antarctica
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/science-world-report
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/antarctica
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/history
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/scientists