The Medieval Warm Period on Maui

As many other researchers have expressed before them with respect to other locations around the world, authors Pau et al. (2012) write that "the response of the tropical Pacific to climate variability such as the Medieval Climate Anomaly (also known as the Medieval Warm Period) ... is an important analogy for understanding projected future climate change." And so they set out to see what they could learn about the well-known global phenomenon on the Hawaiian Island of Maui, developing "a detailed chronology of vegetation and climate change since before human arrival" based on "high-resolution palynological, charcoal, and sedimentological analysis of a sediment core from Kealia Pond, Maui, coupled with archaeological and historical records."

Most pertinent was the three researchers' finding that "a shift from dry to wet climate conditions marked the beginning of the Medieval Climate Anomaly (MCA) as evidenced by a precipitation reconstruction based on a pollen abundance index." They note, for example, that over the 2500 years of their record "there have been two major climatic events: first the MCA (AD 800-1300), followed by the Little Ice Age (AD 1400-1850)." And with respect to this finding, they indicate that "increased rainfall during the MCA in Hawaii supports the evidence that climate dynamics during the MCA was consistent with decreasing El Niño frequency or a persistent La Niña-like state," as espoused by Crowley (2000), Bradley et al. (2003), Cobb et al. (2003) and Mann et al. (2005).

In the case of the early inhabitants of Maui, Pau et al. write that "an increase in forest resources during this wet climate interval coincided with rapid Polynesian population growth," which suggests that the Medieval Warm Period was a time of prosperity for them.

Additional References
Bradley, R.S., Hughes, M.K. and Diaz, H.F. 2003. Climate in medieval time. Science 302: 404-405.

Cobb, K.M., Charles, C.D., Cheng, H. and Edwards, R.L. 2003. El Nino/Southern Oscillation and tropical Pacific climate during the last millennium. Nature 424: 271-276.

Crowley, TJ. 2000. Causes of climate change over the past 1000 years. Science 289: 270-277.

Mann, M.E., Cane, M.A., Zebiak, S.E. and Clement, A. 2005. Volcanic and solar forcing of the tropical Pacific over the past 1000 years. Journal of Climate 18: 447-456.