As a climate scientist, I study past and present changes in the tropical water cycle.

My work uses stable isotopes in present-day water and carbonate-based archives of past climate change, such as stalagmites and terrestrial sediments, to investigate how water balance, precipitation, and large-scale atmospheric circulation patterns respond to global climate change. A key goal of my research is to gain a process-based understanding of the main mechanisms driving past hydroclimate variability. To this end, my work incorporates multi-proxy climate reconstructions, climate-proxy observations, proxy system modeling, and data-model comparison. I have ongoing projects in southern Kenya, Borneo, and Ecuador.

 

PROJECTS

TROPICAL HYDROCLIMATE RECONSTRUCTION

Sunrise over the Olorgesailie Basin in southern Kenya. Photo courtesy of Naomi Levin.

Sunrise over the Olorgesailie Basin in southern Kenya. Photo courtesy of Naomi Levin.

The tropical water cycle impacts the distribution and availability of water resources worldwide. Paleoclimate records from tropical locales are critical to understanding future water balance throughout the tropics and beyond. In my current work, I am reconstructing local water availability and regional hydroclimate in the southern Kenya Rift over the past 500,000 years from terrestrial sediments via a multi-proxy approach that combines clumped isotope thermometry and traditional stable oxygen and carbon isotopes with triple oxygen isotopes -- an emerging new proxy sensitive to evaporation. This new record will be compared with model output from paleo-simulations to better constrain the fundamental drivers of long-term water balance in East Africa, where future projections of moisture availability are highly uncertain. This work is conducted in collaboration with Naomi Levin, Rick Potts, Kay Behrensmeyer, Ben Passey, and the Olorgesailie Drilling Project and funded by the National Science Foundation.

 

WATER ISOTOPES

Collecting dripwater in Lagang Cave at Gunung Mulu National Park, Borneo. Photo by Syria Lejau

Water isotopes are powerful tracers of past hydroclimate variability and provide unique insight into key hydrological processes that cannot be readily obtained from other meteorological and environmental parameters. Establishing the relationship between climate and water isotopes at sites for paleoclimate reconstruction is crucial to constraining how isotopic records reflect past climatic change. In recent work, I investigated how rainfall isotopes in Borneo reflect local precipitation and regional climate phenomena like the Madden Julian Oscillation and El Niño Southern Oscillation (Moerman et al. 2013) and traced how these climatic signals are preserved in cave dripwaters (Moerman et al. 2014). I have on-going investigations in Borneo and Ecuador and will soon launch water collection sites in southern Kenya. Stay tuned! This work is conducted in collaboration with Kim Cobb and Naomi Levin.