Mid-Holocene Climate in Northern Minnesota

• Published in: Quaternary Research
• Main Authors: Forester, Richard M., Delorme, L. Denis, Bradbury, J. Platt
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1987
• Subjects: Ice Sheet
• Online Access: http://dx.doi.org/10.1016/0033-5894(87)90064-0; http://api.elsevier.com/content/article/PII:0033589487900640?httpAccept=text/xml; http://api.elsevier.com/content/article/PII:0033589487900640?httpAccept=text/plain; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400018445

Abstract Study of Holocene ostracodes and diatoms from Elk Lake, in North-Central Minnesota, indicates that the local climate of the mid-Holocene can be subdivided into three intervals. Throughout interval 1 (ca. 7800 to 6700 yr B.P.), climate was colder and much drier than today. During intervals 2 and 3 (ca. 6700 to 4000 yr B.P.) average mean-annual air temperatures approached the modern mean (3.7°C), but warm summers persisted throughout interval 2, whereas during interval 3 warm summers fell into discrete episodes. Furthermore, average mean-annual precipitation was about 85 and 90% of modern during intervals 2 and 3, respectively. Transition times between the principal intervals were less than 50 yr. The expected effects of a retreating Laurentide Ice Sheet that initially maintained a winter-style circulation, followed by transitional climate states, and finally a near-modern circulation pattern may explain these local climatic events.