Thursday, October 23, 2014

New paper demonstrates natural variability controls floods and typhoons in Taiwan

A new paper published in Climate of the Past reconstructs climate in Taiwan over the past 1,900 years and finds typhoons & floods were at "normal" levels over the 20th century, and were at much higher levels during the pre-Medieval Warm Period and second half of the Little Ice Age. 

In addition, the paper shows in fig. 9 that ENSO events have been relatively uncommon during the modern era [opposite of alarmist claims], and that sea surface temperatures were warmer during the Medieval Warm Period and pre-Medieval Warm Period than during modern times since 1850. 

The paper corroborates many others demonstrating drought and flooding cycles are controlled by natural variability of ocean oscillations and accumulated solar activity, not CO2 levels. Several papers also find the hydrological cycle linked to solar activity, another of many potential solar amplification mechanisms.

Clim. Past, 10, 1857-1869, 2014

L.-C. Wang1,2, H. Behling1, T.-Q. Lee3, H.-C. Li4, C.-A. Huh3, L.-J. Shiau5, and Y.-P. Chang6
1Department of Palynology and Climate Dynamics, Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, 37073 Göttingen, Germany
2Collection Management Department, National Taiwan Museum, Taipei 100, Taiwan
3Institute of Earth Sciences, Academia Sinica, Taipei 128, Taiwan
4Department of Geosciences, National Taiwan University, Taipei 106, Taiwan
5Institute of Applied Geosciences, National Taiwan Ocean University, Keelung 202, Taiwan
6Department of Oceanography, National Sun Yat-sen University, Kaohsiung 804, Taiwan

Abstract. We reconstructed paleoenvironmental changes from a sediment archive of a lake in the floodplain of the 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 past floods, typhoons, and agricultural activities in this area which are sensitive to the hydrological conditions in the western Pacific. Considering the high sedimentation rates with low microfossil preservations in our sedimentary record, multiple flood events were. identified during the period AD 100–1400. During the Little Ice Age phase 1 (LIA 1 – AD 1400–1620), the abundant occurrences of wetland plant (Cyperaceae) and diatom frustules imply less flood events under stable climate conditions in this period. Between AD 500 and 700 and the Little Ice Age phase 2 (LIA 2 – AD 1630–1850), the frequent typhoons were inferred by coarse sediments and planktonic diatoms, which represented more dynamical climate conditions than in the LIA 1. By comparing our results with the reconstructed changes in tropical hydrological conditions, we suggested that the local hydrology in NE Taiwan is strongly influenced by typhoon-triggered heavy rainfalls, which could be influenced by the variation of global temperature, the expansion of the Pacific warm pool, and the intensification of El Niño–Southern Oscillation (ENSO) events.

1 comment:

  1. Love your site but need to know who you are and your qualifications; not afraid to know that you are not a climate "scientist" ....