All-Python ccc-gistemp release

I am proud to announce release 0.2.0 of ccc-gistemp.  This is an all-Python reimplementation of GISTEMP, the NASA GISS surface temperature analysis.  Please feel free to download and play with it.  It will automatically fetch input data across the internet, and produce textual and graphical result files.

This release works on Windows, Linux, Mac OS X, FreeBSD, and probably anywhere else you can get Python to work.  The only dependency is on Python (2.5.2 or later, as we discovered today that the code to fetch input data trips over a bug in earlier Python libraries).

The results of running this release match GISTEMP results very closely indeed:

Comparison of ccc-gistemp with GISTEMP, on common input data

In fact, the annual global, northern hemisphere, and southern hemisphere anomaly results are identical, as are the southern hemisphere monthly anomalies.  The global monthly anomalies differ 7 times, out of more than 1000, each time by one digit in the least-significant place.

This ends phase 1 of the CCC-GISTEMP project.  However, although there is no remaining Fortran, ksh, or C source code, much of is still GISS code, and a lot of the large-scale structure of the code is still dictated by its 1980s Fortran heritage.  For instance, the data is broken up into pieces because it couldn’t all fit into memory at once [ed: 2010-01-19: this particular instance is Issue 25 and it's now fixed].  This obscures the underlying algorithms being applied.  Phase 2 of CCC-GISTEMP will refactor the code to eliminate this obscurity.  We expect one side-effect to be an increase in speed.

Thanks to all who have contributed, including David Jones, Paul Ollis, Gareth Rees, John Keyes, and Richard Hendricks. Thanks also to Reto Ruedy at GISS, who has been helpful and responsive.

5 Responses to “All-Python ccc-gistemp release”

  1. drj Says:

    It looks like STEP 1 fails when using Python 2.5.2. Anyone using the Python 2.5 series really should be using 2.5.4 anyway (the most up to date 2.5.x release).

  2. Rattus Norvegicus Says:

    I used it with Python 2.5.6 on Windows and it worked great!

  3. drj Says:

    @Rattus: Thanks! It’s very useful to have reports of ccc-gistemp working on platforms that we don’t have routine access to (like Python 2.5 on Windows XP). If you have the enthusiasm for testing and would like to contribute to the project, please join our mailing list.

  4. How To Prove Your Adjustments Are Correct « Things I Find Interesting Says:

    [...] and other papers describing updates to the procedure. Currently the ccc-gistemp code produces results that are almost identical to the GISS code. As we emulate the exact GISS algorithm more closely, our results get [...]

  5. Nothing | Says:

    [...] and here:, where you can download python code to do the data analysis for yourself. [10] Kerry E. letter [...]

Leave a Reply