Jian Tian Jian Tian

Ph.D. student
Department of Plant Biology


Holocene climatic fluctuations in the midcontinent of North America

I study Holocene climatic fluctuations, focusing on the midcontinent of North America. I use a variety of climate proxies from lake sediment, including oxygen isotopes from carbonates, trace element geochemistry, mineralogical composition, and biological indicators of productivity. Preliminary results from Steel Lake, Minnesota, show distinct climate characteristics over different periods of the Holocene, including both abrupt climate change and cyclic oscillations. This site has varved sediments, providing precise chronological control enabling high-resolution analyses.

Research approach

  • Selecting sites in a climatically-sensitive region allows accurate documentation of past climate fluctuations.

  • Varved sediments provide precise chronological control and enable high-resolution analyses.

  • A multiple-proxy approach results in a comprehensive understanding of the system.

Research objectives

  • Calibrate various climatic proxies in varved sediments with available instrumental weather data to evaluate how each proxy is related to climatic factors.
  • Assess Holocene climatic variations, particularly cyclic and abrupt changes, by interpreting proxy records from all four lakes based on calibration results.
  • Integrate our new varved sediment data with findings from other high-resolution paleoclimatic studies in adjacent areas to provide a regional synthesis of Holocene climatic variations.
  • Compare patterns of climatic fluctuations in the midcontinent of North America with those in Greenland, North Atlantic, and other parts of the globe to evaluate patterns and mechanisms of Holocene climatic variability.

Target lakes

Steel Lake 46° 58'N, 94° 41'W Hubbard County, MN
Lake Olaf 46° 37'N, 96° 11'W Otter Tail County, MN
Deep Lake 47°41'N, 95°22'W Clearwater County, MN
Twin Lakes 46°47'N, 95°52'W Becker County, MN

Department of
Plant Biology

School of
Integrative Biology

Department of

Program in Ecology & Evolutionary Biology

University of Illinois

updated 06/26/03