About 34 million years ago, the first major Antarctic ice sheets appeared, suggesting that major cooling had taken place; however, the global transition into this icehouse climate remains poorly constrained.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/early-palaeogene-temperature-evolution-southwest-pacific-ocean
[2] http://admin.indiaenvironmentportal.org.in/category/author/peter-k-bijl
[3] http://admin.indiaenvironmentportal.org.in/category/author/stefan-schouten
[4] http://admin.indiaenvironmentportal.org.in/category/author/appy-sluijs-et-al
[5] http://admin.indiaenvironmentportal.org.in/category/journal/nature
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/south-pacific-ocean
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-science
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/antarctica