Broadly speaking, my research interests are in the field of paleoceanography/paleoclimatology, which aims to reconstruct the Earth’s climate history as well as to understand the nature and cause(s) of past climatic events. These will serve as the basis for the scientific community to precisely predict future global warming and climate change as a result of ongoing human CO2 emissions from fossil fuel burning.
To achieve these missions, we often rely on various types of climate archives or “climate proxies”. A prime example is the microscopic fossils of foraminifers. These single-celled organisms produce intricate shells made of calcium carbonate (CaCO3), which sink to the ocean floor and are subsequently buried into sediments after their life-cycle is over. These fossil shells act as “time-capsules” in such a way that their biogeochemical characteristics enable us to unravel past environmental conditions at the time of shell formation. For instance, oxygen isotopes and magnesium contents of shell CaCO3 are widely utilized as the proxies for seawater temperatures. The abundance and isotopic composition of boron in shell CaCO3 are proposed to reflect seawater pH and/or other ocean carbonate chemistry parameters, which can be translated into ancient atmospheric CO2 levels. However, calibrations and applications of these proxies are often challenged by biases due to numerous factors including vital effects (related to biological processes by foraminifers and their symbiotic algae if present) and kinetic effects (related to the rate of shell growth).
My research projects are directed toward identifying such biases in climate proxies and understanding the controlling mechanisms, for which I typically employ various types of inorganic CaCO3 precipitation experiments in the laboratory. These experiments allow me to characterize chemical/physical/biological controls on the incorporation of certain stable isotopes and trace elements into synthetic CaCO3 under tightly controlled conditions. Such information can be extremely valuable to comprehensively model how isotopes and trace elements are incorporated into foraminiferal CaCO3, which helps us to properly isolate and correct for the biases in climate proxies and thereby to improve the overall accuracy in paleoclimate reconstructions.
To achieve these missions, we often rely on various types of climate archives or “climate proxies”. A prime example is the microscopic fossils of foraminifers. These single-celled organisms produce intricate shells made of calcium carbonate (CaCO3), which sink to the ocean floor and are subsequently buried into sediments after their life-cycle is over. These fossil shells act as “time-capsules” in such a way that their biogeochemical characteristics enable us to unravel past environmental conditions at the time of shell formation. For instance, oxygen isotopes and magnesium contents of shell CaCO3 are widely utilized as the proxies for seawater temperatures. The abundance and isotopic composition of boron in shell CaCO3 are proposed to reflect seawater pH and/or other ocean carbonate chemistry parameters, which can be translated into ancient atmospheric CO2 levels. However, calibrations and applications of these proxies are often challenged by biases due to numerous factors including vital effects (related to biological processes by foraminifers and their symbiotic algae if present) and kinetic effects (related to the rate of shell growth).
My research projects are directed toward identifying such biases in climate proxies and understanding the controlling mechanisms, for which I typically employ various types of inorganic CaCO3 precipitation experiments in the laboratory. These experiments allow me to characterize chemical/physical/biological controls on the incorporation of certain stable isotopes and trace elements into synthetic CaCO3 under tightly controlled conditions. Such information can be extremely valuable to comprehensively model how isotopes and trace elements are incorporated into foraminiferal CaCO3, which helps us to properly isolate and correct for the biases in climate proxies and thereby to improve the overall accuracy in paleoclimate reconstructions.
Live planktonic foraminifera, Orbulina universa.
The central shell is typically a few millimeter in size.
Photo from Dr. Howard J. Spero (Univ. of California Davis)
Examples of fossil foraminiferal shells sampled from marine sediments.
Source:
Miller et al. (2008) Eocene-Miocene global climate and sea-level
changes: St. Stephens Quarry, Alabama. GSA Bulletin, v120, n1-2,
p34-53