Hobart

Seminar Abstract

Thursday 11 March 2010, 11.30am (Tas time)
CSIRO Auditorium, Hobart

Peter J Gleckler
Frohlich Fellow/Research Scientist
Program for Climate Model Diagnosis and Intercomparison (PCMDI)
Lawrence Livermore National Laboratory
Livermore, California, USA

Exploring the impact of uncertainties in the detection and attribution of basin scale ocean warming

Large-scale increases in upper ocean heat content are evident in the observational record of the past fifty years. Several studies have made use of well established Detection and Attribution (D&A) methods to demonstrate that these changes are consistent with increasing concentrations of greenhouse gases and can not be explained by natural variability. Identification of systematic biases in historical XBT temperature measurements have led to new estimates of global-scale ocean heat content variability and trends, both of which are key to D&A research. In the present study we use these newer estimates to re-examine the issue of ocean warming and its causes, and in the process we will explore the sensitivity of our analysis to measurement biases, sampling uncertainties, common approaches used to remove simulation drift, and volcanic forcings in model simulations. Previous D&A studies of ocean warming have relied on individual model simulations, whereas here we use a recently established approach to work in a multi-model context. In the simulations evaluated here, the warming signature is predominantly sensitive to whether or not volcanic forcings are included. However, we find estimates of longer time scale temperature variability to be sensitive to all of our tests, thereby influencing estimates of signal-to-noise ratios. Our results are consistent with the findings of previous studies (i.e., positive detection) and robust to the uncertainties considered here.

Peter Gleckler is a research scientist at the Program for Climate Model Diagnosis and Intercomparison (PCMDI), Lawrence Livermore National Laboratory, USA. He and his colleagues work with the international modeling community to design and implement the World Climate Research Programme's Coupled Model Intercomparison Project (CMIP). In addition to his research in the detection and attribution of ocean warming, he also is engaged in efforts to develop performance metrics for climate models.

Seminar recording

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Clothilde Langlais, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5399
Natalie Kelly, (Biology/Modelling seminars) CSIRO Marine and Atmospheric Research 0438 452 483
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 11/05/10