LME | Last Millennium Ensemble Project

The CESM Paleoclimate Working Group at NCAR conducted a series of Last Millennium community experiments, referred to as the Last Millennium Ensemble (LME).  The LME used a ~2-degree atmosphere and land, ~1-degree ocean and sea ice version of CESM-CAM5_CN (1.9x2.5_gx1v6). Ensemble members extend from 850 to 2006 using reconstructions for the transient evolution of solar intensity, volcanic emissions, greenhouse gases, aerosols, land use conditions, and orbital parameters, together and individually. We have completed 36 simulations for the LME project: 13 simulations with all transient forcings, smaller ensembles with each transient forcing separately, and long 1850 and 850 control simulations. Ensemble spread is generated using round-off differences in the initial atmospheric state. Monthly, daily, and 6-hourly outputs are saved and archived on the Earth System Grid (http://www.earthsystemgrid.org) as single variable timeseries.

The CESM-CAM5 LME project is a community project. Output from the ensemble members are available to any scientist who is interested. Bette Otto-Bliesner (ottobli@ucar.edu) at NCAR is leading the planning effort on behalf of the community. Nan Rosenbloom and Andy Mai were instrumental in the setup and running of the LME simulations. Substantial computing resources for the project were awarded as a part of the CESM community CSL allocation on Yellowstone.  Please contact us if you can contribute additional ensemble members with the same or different forcing reconstructions. Please sign up on our mailing list for future updates.

A first look at select climate metrics can be viewed and downloaded here. Users may also be interested in the Climate Variability Diagnostics results found here.

If you are interested in analyzing the CESM-CAM5 Last Millennium Ensemble, we kindly ask that you provide a short description of your proposed research focus and your contact information. Please send this information to Bob Tomas (tomas@ucar.edu) so that other users can see what projects are underway. A list of projects can be found here.

A list of publications using the Last Millennium Ensemble can be found here. If you would like to add a publication to this list, please contact webhelp@cgd.ucar.edu. When presenting results either in oral or written form, please acknowledge the CESM1(CAM5) Last Millennium Ensemble Community Project and supercomputing resources provided by NSF/CISL/Yellowstone. An overview paper of the Last Millennium Ensemble Project should be cited as follows:

Otto-Bliesner, B.L., E.C. Brady, J. Fasullo, A. Jahn, L. Landrum, S. Stevenson, N. Rosenbloom, A. Mai, G. Strand. Climate Variability and Change since 850 C.E.: An Ensemble Approach with the Community Earth System Model (CESM), Bulletin of the American Meteorological Society, 735-754 (May 2016 issue). [Article Download]