CCR Staff: Bette Otto-Bliesner, Senior Scientist
Bette Otto-Bliesner is a Senior Scientist in the Paleoclimate Group in the Climate and Global Dynamics Division at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado.
Born in Chicago, Illinois, Otto-Bliesner first became interested in Meteorology as a child watching P.J. Hoff, the CBS affiliate weatherman. She earned her doctorate in Meteorology in 1981 at the University of Wisconsin - Madison. She worked at NCAR in the GCM group from 1974-1976 and rejoined NCAR in 1995, coming from a faculty position in the Geology Department at the University of Texas at Arlington.
Otto-Bliesner's research interests are in using computer-based models of Earth's climate to investigate past climate change and climate variability across a wide range of time scales. She is particularly interested in climate change forced naturally over the glacial-interglacial cycles of the last million years.
Bette Otto-Bliesner serves on the scientific steering committees for the International Geosphere-Biosphere Programme (IGBP) Past Global Changes (PAGES) and the Paleoclimate Modeling Intercomparison Project PMIP2. She is a Lead Author for Chapter 6, Paleoclimate, of the IPCC Fourth Assessment Report.
CV (short version)
Last Glacial Maximum ocean thermohaline circulation: PMIP2 model intercomparisons and data constraints (.pdf)
Arctic Warmth and the Greenland Ice Sheet During the Last Interglaciation (.pdf)
Climate Modeling of the Last Glacial Maximum and Mid-Holocene (.pdf)
Climate Sensitivity to Preindustrial Forcings(.pdf)
Modeling El Nino and Its Teleconnections During the Last Glacial-Interglacial Cycle (.pdf)
Climate Simulation of the Late Cretaceous Ocean (.pdf)
Vegetation-Climate Feedbacks During the Latest Cretaceous (.pdf)
Current Research Projects
Milankovitch Orbital Forcing of Past Climates
I am interested in using climate models to identify the mechanisms and quantify the feedbacks that regulate the climate response to orbital changes of latitudinal and seasonal solar radiation. Paleoclimate records indicate that glacial-interglacial variations in regional climates are consistent with our understanding of orbital forcing. I first became involved in modeling the climate response to Milankovitch orbital variations in 1982, when John Kutzbach and I used a low-resolution general circulation model to explain evidence of an enhancement of the summer Asian-African monsoon during the Holocene period (9000 years ago).
Using the NCAR Community Climate System Model (CCSM) we have also confirmed that Milankovitch orbital variations are important for explaining the modulation of El Ni�o-Southern Oscillation (ENSO) over glacial-interglacial cycles as found in the proxy records due to changes in the variability and teleconnections. With Paleo Group colleagues Esther Brady and Bob Tomas, we are continuing our efforts to understand Quaternary climates and have completed fully coupled simulations of the mid-Holocene and Last Glacial Maximum with CCSM3.
Arctic Warmth and the Greenland Ice Sheet
I am currently also working closely with the paleodata and ice sheet modeling communities to examine the warm Arctic summers during the Last Interglaciation and impact on the polar ice sheets of Greenland and Antarctica and global sea level. These calculations show summers 3 to 5�C warmer than today in the Arctic, especially over and near Greenland, in very good agreement with the IGBP CAPE (CircumArctic PaleoEnvironments) proxy data synthesis. Ice cores in Greenland indicate that the Greenland ice sheet was significantly smaller during this interglaciation. Calculations with the University of Calgary ice sheet model show that the substantial melting of the Greenland ice sheet and the complete melting of the nearby eastern Canadian icefields likely contributed 2 to 4 meters of sea level rise during this past time period.
The results are quite relevant to assessments of projections of future climate change. The Arctic summer warmth during the Last Interglaciation is comparable to what might be expected by year 2100 if greenhouse gases increase to an equivalent radiative forcing of a tripling of atmospheric carbon dioxide (although the impact on the Greenland ice sheet will likely take several centuries more). This is a collaborative project with Jonathan Overpeck at the University of Arizona, Shawn Marshall at the University of Calgary, Gifford Miller at the University of Colorado, and the IGBP CAPE project.
Response of Climate to Freshwater Forcing
Proxy records indicate that the locations and magnitudes of freshwater forcings to the Atlantic Ocean basin as iceberg discharges into the high-latitude North Atlantic, Laurentide meltwater input to the Gulf of Mexico, or meltwater diversion to the North Atlantic via the St. Lawrence River and other eastern outlets may have influenced the responses of the North Atlantic thermohaline circulation and global climate. I am intrigued with geologic evidence that some events, such as Meltwater pulse 1a, were associated with significant sea level rise but only a slowdown of Atlantic meridional overturning circulation (MOC), while other events, such as Heinrich event 1, have less evidence of rapid sea level rise but were marked by near collapse of the MOC. In collaboration with Paleo Group members Esther Brady and Nan Rosenbloom and NOAA scientist Carrie Morrill, we are using the NCAR Community Climate System Model (CCSM3) to investigate the roles of the amounts, locations and timings of freshwater forcings.
Coupled Climate System Response at Last Glacial Maximum
I am involved in the International Paleoclimate Modeling Intercomparison Project (PMIP2) to simulate the Last Glacial Maximum using a common set of forcings and boundary conditions in coupled atmosphere-ocean models. The objective is to improve comparison among models and with data and to provide benchmarks for simulations being used for future climate change projections. Our analyses show that models give very different glacial thermohaline circulations even with comparable simulations for present and identify an important role for sea ice in the polar regions of both Northern and Southern Hemispheres in driving the ocean response to glacial forcing.