On April 9, 2018, Richard Neale, Project Scientist at the National Center for Atmospheric Research (NCAR, Boulder, Colorado, USA), presented a selection of results showing the evolution of simulation skill through six generations of the NCAR atmosphere model (CCM3 to CAM6) and five generations of the NCAR coupled model (CCSM2 to CESM2) spanning more than 20 years, during the CMCC webinar titled: “A History of Bias in the NCAR Community Earth System Model: 20-years of Successes, Tough Choices and Persistent Problems”.

Watch the video:

During this time the complexity of models have increased dramatically in almost every respect. These increases in complexity aim to target missing or poorly represented processes and interactions in models. However, an improved simulation, where new representations are thought to play a substantial role, is frequently not guaranteed. Although advances compared to early model versions are undeniable, they are not monotonic in nature, and certain degradations often come at the expense of including these new processes, a result of the inevitable trade-offs that come with model development.

Download the webinar presentation (pdf) by R. Neale.