Tag Archives: Climatic change

A Questionable Interview on Climatic Change

Today’s afternoon, there was an interview with the Austrian limnologist Prof. em. Wilhelm Ripl in Deutschlandfunk’s “Zwischentöne” [5]. Whilst mentioning a couple of very interesting things, Ripl also said a few things that can’t be left without criticism.

Ripl was criticizing that established climatic models are making use of data which is of questionable representativity stating that it is not possible to use such data for statistic analysis and averaging because it is “non-statistical in some way”. He was also bemoaning that too much funding was spent on computer simulations which he thinks are in principle unable to represent the global climatic processes accurate. Fist of all, the climatic models used nowadays are consistent and correct as approved by measurement as shown below. At least for a time range of decades. No one can deny this.

Figure 1.1 (p. 98) from ref. 1.

Figure and description taken from ref. 1.

He was further criticizing that the models exclude the processes of (especially small scale) heat transfer via water vaporization and condensation. I’m not an expert on climatic modeling but a quick research on the topic lead me to NASA Earth Science’s Integrated Biosphere Simulator (IBIS) [2] which seems to implement just what Ripl felt was missing. It is an Open Source Fortran framework that allows for Dynamic Global Vegetation Modeling (DGVM). (Freely available from [3].) It is described in a well cited review article by Foley et al. (1996), [4]. Unfortunately, my university refuses to by this journal so I was left with the abstract but I’ll post an update as soon as I could manage to read the whole article.

At an other point, Ripl makes the very strange claim that giving off energy by radiation into empty space was impossible. I’m not certain if he maybe just confused his own words but taken as given, the statement is of course complete nonsense. Radiating means emitting photons, each of them having a relativistic energy of E = h c / λ. Where h is Planck’s constant, c is the speed of light and λ is the wavelength of the emitted photon. Thus the emitter looses this energy with each photon being sent to outer space. If this process was not existing, all stars (and many other things) were to explode immediately.

Last but not least, he (and the interviewer) were mentioning several times that meteorologists should not focus exclusively on carbon dioxide as the only green house gas. They don’t do so at all. But one has to be careful if listening to them. Many models do not account for each green house gas explicitly (which would mean rather unfeasible computational effort) but instead use a “virtual” green house gas measured in CO2 equivalents. That is, if a substance, say methane, is 25 times more active as a green house gas than is CO2 it accounts for 25 CO2 equivalents. The factor 25 is called the Global warming potential (GWP) for methane. Determining the GWP must not only account for the green house activity but also the retention time of the gas in the atmosphere. For example, methane is removed from the atmosphere by naturally occurring processes rather quickly while SF6 stays in the atmosphere for thousands of years. The aforementioned value of 25 for methane corresponds to an averaging timespan of 100 years. Frequently, if CO2 is said, CO2 equivalents are actually meant.

I do not want to compromise Prof. Ripl with this text in no way. But I believe that mistakes have to be corrected. Even (or especially) if they were made by honorable scientists.


[1] S. Solomon, D. Qin, M. Manning, Z. Chen, K.B. Marquis, M. ans Averyt, M. Tignor, and H.L. Miller (Eds.), IPCC Fourth Assessment Report (AR4) – Climate Change 2007: The Physical Science Basis. Cambridge University Press, 2007.
[2] NASA Earth Science, Integrated Biosphere Simulator Model (IBIS), Version 2.5. http://daac.ornl.gov/MODELS/guides/IBIS_Guide.html
[3] http://www.sage.wisc.edu/download/IBIS/ibis.html
[4] J. Foley et al., An integrated biosphere model of land surface processes, terrestrial carbon balance, and vegetation dynamics. Global Biogeochemical Cycles, 10(4):603-628, 1996.
[5] Zwischentöne – Der Limnologe Wilhelm Ripl im Gespräch mit Michael Langer. Deutschlandfunk, 2011-05-01 13:30 (CEST). http://www.dradio.de/dlf/playlist/dlf_zwischentoene/1445206/

Do you believe in Climatic Change?

Since I got asked again and again, whether or not I believe in climatic change, I feel about posting a final clarifying statement on that issue. I did not become a scientist to make my decisions on the ground of obscure conveniences but on the bases of provable facts. Continue reading