The fifth workshop of the CLIVAR International Climate of the Twentieth Century Project (C20C) was held on 25-28 October 2010 in Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS) in Beijing, China. The goals of the workshop were to review progress on ongoing C20C experiments, discuss potential contributions to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), discuss collaborations with other projects (e.g. LUCID), and make plans for future experiments.

About 40 scientists from China, USA, UK, France, Italy, Russia, Japan, Sweden and South Africa attended the workshop and gave 30 presentations. The workshop also discussed the following issues:

？New core C20C Detection and Attribution project 
？Application of HadISST2 to C20C and feedback on completing this data set
？LUCID and C20C – land surface processes, climate variability and change
？Simulating rainfall over the last century compared to a new data set
？Application of  Frederiksen and Zheng (2004) method to estimating seasonal predictability