Pollen data suggest that the Greenland ice sheet was much smaller during previous warm periods.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/sprucing-greenland
[2] http://admin.indiaenvironmentportal.org.in/category/author/eric-j-steig
[3] http://admin.indiaenvironmentportal.org.in/category/author/alexander-p-wolfe
[4] http://admin.indiaenvironmentportal.org.in/category/journal/science
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-science
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/global-warming
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/greenland