Map source here. Read here. Anderson et al. used sea core sediments to reconstruct temperatures of the Norwegian Sea surface over the last 3,000 years. Research clearly identified the Roman warming, Dark Ages cooling, Medieval warming and the Little Ice Age cooling. Research also showed historical temperatures warmer than those experienced in the Norwegian Sea during the modern era.
"The climate history derived from this study is remarkably similar to that derived by McDermott et al. (2001) from a high-resolution speleothem ð18O record obtained from a stalagmite discovered in a cave in southwestern Ireland. At the beginning of the 3000-year-long Voring Plateau record, both regions were clearly in the end-stage of the long cold period that preceded the Roman Warm Period...both regions begin their descent into the Dark Ages Cold Period, which held sway until the increase in temperature that produced the Medieval Warm Period...Last of all, the Little Ice Age is evident, with cold periods centered at approximately 400 and 100 years BP.....Andersson et al. report that "surface ocean conditions warmer than present were common during the past 3000 years."
Additional climate history postings. Historical temperature charts. Modern temperature charts.