“Coral records of 20th century central tropical Pacific climate:
Signatures of natural and anthropogenic climate change”
Dr Intan Suci Nurhati
Singapore-MIT Alliance for Research and Technology
Friday 08 Oct 2010: 2pm – 3pm
DBS Seminar Room 1 (Blk S2, Level 4; map)
Host: Jani thuaibah
About the talk – Accurate forecasts of future climate changes depend on quantifying anthropogenic trends against a rich background of natural climate variability. The tropical Pacific is the home of the strongest natural climate variability affecting our modern climate known as the El Niño-Southern Oscillation (ENSO) – making climate trends in this region a critical piece of our understanding. However, the detection of anthropogenic signatures in the tropical Pacific has been hampered by the lack of continuous century- long instrumental climate records available from the region.
Coral skeletal geochemistry, such as the ratio of oxygen isotopic composition (d18O), has provided valuable tropical climate records. Coral d18O records throughout the central tropical Pacific suggest that this region experiences warming and/or increased rainfall trends since the late 20th century that may be unprecedented over the last millennium. It is important to identify the physical changes that underlie this late 20th century trend with respect to the roles of temperature and hydrological changes in the coming decades.
In this talk, I present coral-based sea-surface temperature and salinity proxy records from the central tropical Pacific over the 20th century, via coupled measurements of coral d18O as well as Sr/Ca. The central tropical Pacific sea- surface temperature proxy records show significant correlations to the canonical ENSO variability as well as to the recently identified “flavor” of ENSO called the ENSO Modoki.
Despite the tight coupling of temperature and rainfall in the tropics over annual and interannual (3-7 years) timescales, the coral records suggest that the decadal and secular trends of tropical Pacific sea-surface temperature and hydrology are controlled by different sets of dynamics, and also, may response differently to global warming. Taken together, the new coral proxy records suggest that anthropogenic climate change may dominate recent hydrological trends in the region, which carries important implications to our societies.
About the Speaker – Dr. Intan Suci Nurhati studies how the tropical Pacific climate may change under global warming, by reconstructing the past climate using coral geochemistry. She received her B.A. in Earth and Environmental Science, and Economics from Wesleyan University (USA) in 2005, and earned her Ph.D. in Earth and Atmospheric Science from Georgia Institute of Technology (USA) in 2010. She is currently a postdoctoral associate at the Singapore-MIT Alliance for Research and Technology, investigating coral-based records of marine environmental metals in Singapore, and the regional hydrological changes under the warming climate.