The paper also demonstrates flooding was more common during the Little Ice Age and Dark Ages Cold Period, and that the frequency of El Ninos/La Ninas is currently near the mean over the past 2000 years.
Clim. Past Discuss., 10, 1977-2009, 2014
1Department of Palynology and Climate Dynamics, Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, 37073 Göttingen, Germany
2Institute of Earth Sciences, Academia Sinica, Taipei, 128, Taiwan
3Department of Geosciences, National Taiwan University, Taipei, 106, Taiwan
4Institute of Applied Geosciences, National Taiwan Ocean University, Keelung, 202, Taiwan
5Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 804, Taiwan
Abstract. In this study, we reconstructed the paleoenvironmental changes from a sediment archive of the floodplain lake in Ilan Plain of NE Taiwan on multi-decadal resolution for the last ca. 1900 years. On the basis of pollen and diatom records, we evaluated the record of past vegetation, floods, typhoons and agriculture activities of this area, which is sensitive to the hydrological conditions of the West Pacific. High sedimentation rates with low microfossil preservations reflected multiple flood events and humid climatic conditions during 100–1400 AD. A shortly interrupted dry phase can be found during 940–1010 AD. The driest phase corresponds to the Little Ice Age phase 1 (LIA1, 1400–1620 AD) with less disturbance by flood events, which enhanced the occurrence of wetlands (Cyperaceae) and diatom depositions. Humid phases with frequent typhoons are inferred by high percentages of Lagerstroemia and high ratios of planktonic/benthic diatoms, respectively, during 500–700 AD and Little Ice Age phase 2 (LIA2, 1630–1850 AD). The occurrences of cultivated Poaceae (Oryza) during 1250–1300 AD and the last ~400 years, reflect agriculture activities, which seems to implicate strongly with the environmental stability. Finally, we found flood events which dominated during the El Niño-like stage, but dry events as well as frequent typhoon events happened during the La Niña-like stage. After comparing our results with the reconstructed proxy for tropical hydrological conditions, we suggested that the local hydrology in coastal East Asia were strongly affected by the typhoon-triggered heavy rainfalls which were influenced by the variation of global temperature, expansion of the Pacific warm pool and intensification of ENSO events.
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