MGGD Research Areas

Faculty

Paleoenvironment

Ordy Pond thumbnail photo. An invaluable tool for understanding and predicting changes planet Earth will face in the 21st century is studying the changes that have taken place in the past. Paleo-atmospheric and oceanic reorganizations, as well as changes in atmospheric greenhouse gases are recorded in ice cores, sediment cores, and other paleo-indicators, which provide unique information about natural feedbacks in the Earth system on time scales that are not covered by the short duration of modern observations. Reconstruction and analysis of Earth’s climatic history assists us in improving our fundamental understanding of the system and helps us in predicting future changes, following the motto: "The past as the key to the future".

Within the Marine Geology and Geochemistry Division, observational, experimental and theoretical studies are conducted that cover a broad spectrum of paleoenvironmental research. This includes development of Earth system-, climate- and carbon cycle models

at the global scale as well as process-modeling of paleo-proxy incorporation in individual organisms at the micrometer scale. Another focus of paleoenvironmental studies conducted in the Division is the reconstruction of specific climate episodes and events, including the Holocene and the Paleocene-Eocene Thermal Maximum. Some of those endeavors require development of novel analytical techniques such as compound specific isotopic analysis of biomarkers and the establishment of new dating methods for lacustrine sediments. The long-term goal here is the reconstruction of Holocene tropical climate changes based on lake sediments from the Hawaiian Islands and other sites within the Pacific. Further efforts of the Division include understanding of the past and present biogeochemistry and cycling of phosphorus in marine, lacustrine, and riverine systems.

The Division’s interests in the area of paleoenvironmental research may be summarized by the following themes:

Eocene topography thumbnail graphic. Past Climate Aberrations. Studying past climate events helps us to better understand the present and improve predictions for future climate change. For example, during the Paleocene-Eocene Thermal Maximum (PETM, 55 million years ago), Earth’s surface temperature rose globally by 5–9° C within a few thousand years. A great deal of our knowledge about past climate events is based on analyses of deep-sea sediment cores drilled by the Ocean Drilling Program (ODP). The figure shows the eocene configuration of continents and several OPD sites where PETM sections were recovered.

[ ABOVE ] Ordy Pond is a permanently flooded sinkhole located on the former Barbers Point Naval Air Station in Ewa, O‘ahu. The pond contains 13.5 m of aquatic sediment dating from just under 10,000 years to present. This laminated sequence is the best-preserved, continuous, high resolution Holocene sedimentary record in the Hawaiian Islands, and probably in the central Pacific. The 5 m water column is brackish, eutrophic, and supersaturated with respect to aragonite and calcite. It undergoes seasonal stratification, but the bottom waters remain anoxic year round. Algal productivity and inorganic carbonate precipitation vary seasonally. UH researchers are in process of preserving Ordy Pond as a natural reserve for continuing and future research on O‘ahu’s environmental, climatic, and vegetation history, as well as for future studies of biogeochemical processes in the water column and of the surrounding wetland flora and fauna.

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