12-13 May 2022
Max Planck Institute for Evolutionary Biology
Europe/Berlin timezone

OSS in Climate Modelling, Introducing a Software Policy at an MPI

13 May 2022, 11:05
Lecture Hall (Max Planck Institute for Evolutionary Biology)

Lecture Hall

Max Planck Institute for Evolutionary Biology

August Thienemann Strasse 2 24306 Plön Germany
onsite Session 5


Reinhard Budich (MPI for Meteorology) Maximilian Funk (MPI for Meteorology)


The Climate Model „ICON“ has been developed at MPI for Meteorology for climate and weather
The model consist of approx. 500 k lines of (much legacy) code developed by 100s of people
across the world and is under constant change due to porting to the most modern HPC
architectures. Code owner are 4 institutions: MPI-M, DWD, KIT and DKRZ
These institutions had been developing the code on the legal basis of cooperation agreements.
A license specifically drafted by a law firm as “open-source-like”, has not proven useful . Among
the problems with this license were the facts that it has not been accepted by many journals,
and put up too high hurdles for the community of climate scientists to pick up the code easily
and modify it for their use cases: Proliferation of the code into the community was unsatisfyingly
After these experiences the idea was accepted, that licensing the code as open source software
would solve many of such problems.
The selection of the most appropriate form of OSL rose quite some discussion amongst the
parties involved: We opted for the permissive BSD. We drafted two documents, a software
policy and a contributors license agreement that would enable MPI-M to license all their
software development and especially “their” parts of ICON as Open Source software, under the
BSD-3-Clause license.
We are hoping to promote the development and use of ICON worldwide, enabling researchers
changing institution during their career to be able to continue to use “their” work, taking away
the pain of thinking about how to license from researchers, establishing a fair way of sharing IP
rights between MPG and the individual coder .
In our presentation we will try to shortly explain the legal background and the legal meanings of
both documents, describe the process it took to implement these documents at the institute
(Directors board, Betriebsrat, etc.) and illuminate which IT- and personal infrastructure is
needed for the policy to work.

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