The source code of the MIT Earth System Model is publicly available for non-commercial research and educational purposes via github (i.e. github.com:mit-jp/igsm.git). Under this open source protocol, we have also established a software license through the MIT Technology Licensing Office. As the MESM has embedded models developed at three other institutions, appropriate copyright clearances for the third-party code are required. If you wish to access the MESM software, please download and complete the software license form and submit your request to mesm-request@mit.edu.