Pau, S., MacDonald, G.M. and Gillespie, T.W. 2012. A dynamic history of climate change and human impact on the environment from Kealia Pond, Maui, Hawaiian Islands.
From the abstract:
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. Charcoal increases around AD 840-1140 signal the presence of Polynesians in the Keālia Pond region, but there is no evidence of rapid and extensive forest clearance immediately after Polynesian arrival.
What was done
Based on "high-resolution palynological, charcoal, and sedimentological analysis of a sediment core from Kealia Pond, Maui, coupled with archaeological and historical records," as they describe it, Pau et al. developed "a detailed chronology of vegetation and climate change since before human arrival."
What was learned
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 Hawai'i supports the evidence that climate dynamics during the MCA was consistent with decreasing El Nino frequency or a persistent La Nina-like state," as espoused by Crowley (2000), Bradley et al. (2003), Cobb et al. (2003) and Mann et al. (2005).
What it means
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, especially when compared with the Dark Ages Cold Period and Little Ice Age that preceded and followed it, much as has also been found for many other places around the world. See, in this regard, various reviews archived under Medieval Warm Period in CO2 Science's Subject Index.
Although the Alarmists deviously insist that the MWP was only a Northern Europe phenomenon
this paper shows that Hawaii was affected. See, in this regard, various reviews archived under Medieval Warm Period in CO2 Science's Subject Index.