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. Annals of the Association of American Geographers 102: 748-762.
Based on "high-resolution palynological, charcoal, and sedimentological analysis of a sediment core from Kealia Pond, Maui, coupled with archaeological and historical records," Pau et al. developed "a detailed chronology of vegetation and climate change since before human arrival," finding that "a shift from dry to wet climate conditions marked the beginning of the Medieval Climate Anomaly as evidenced by a precipitation reconstruction based on a pollen abundance index." And on this basis they identified the MWP as occurring over the period AD 800-1300.