Interview with Hartmut Graßl on occasion of the EMS Silver Medal

"At first I was afraid of physics, so I studied meteorology instead."

On September 11, Prof. Hartmut Graßl, Director Emeritus at the Max Planck Institute for Meteorology (MPI-M) and Professor Emeritus at the Meteorological Institute at the University of Hamburg, will receive the highest distinction from the European Meteorological Society, for his "leading role in shaping climate science and his exceptional ability to communicate climate science to his colleagues, to politicians and to the public." The 73-year-old spoke with us about the development of climatology from an exotic discipline to multi-million dollar "big science", and about how scientific discoveries are finding their way into everyday politics.

KlimaCampus: Professor Graßl, you've been working in climate research for over 40 years, you were there at its beginning and campaigned on the subject long before people were aware of climate change - neither in Germany nor internationally. You've raised awareness among politicians and officials and were director of the "World Climate Research Programme" for five years. Could you have imagined any of this when you started studying in Munich? How did you become interested in climate research?

Graßl: I had an excellent, far-sighted and visionary teacher, Prof. Möller at the Ludwig Maximilians University in Munich, where I began my meteorological degree. In his own doctoral thesis back in 1932, he developed a nomogram for determining the net longwave radiation flux in the atmosphere for the three major climate gases: water vapor, CO2 and ozone, which Smagorinsky, Manabe und Wetherald used in their first three-dimensional climate models at Princeton.

KlimaCampus: While you were studying, did you have any idea in which direction climate research would be heading?

Graßl: Yes, of course! I believed my teacher, Fritz Möller. Initially I studied meteorology because I thought it was the easy option. But I quickly realized that there was a lot of mathematics and physics involved (laughs). After finishing my intermediate diploma, I changed to physics. Professor Bopp, the chair holder for theoretical physics - one of the "Göttingen Eighteen"*1, but I didn't know this at the time - tested me briefly on theoretical mechanics, and then he wrote on my meteorology intermediate diploma: "This certificate includes basic studies in physics" and with that I was a physics student and I never went to another compulsory meteorology lecture, even though it was my minor.

Colleagues: past and present directors at the MPI-M in January 2006: Prof. Hartmut Graßl with Prof. Guy Brasseur (current Director of the Climate Service Center in Hamburg), Prof. Martin Claußen, Prof. Klaus Hasselmann and Prof. Jochem Marotzke (from left to right) Photo: M. Böttinger, DKRZ

KlimaCampus: At that time, unlike today, climate science as such didn't exist.

"In the beginning the climatologists were a subset of the meteorologists"

Graßl: No, the climatologists were a subset of the meteorologists and mainly made a weather synthesis based on statistical methods, but they were also responsible for running a lot of weather stations. As a student - before I went into climate research - I interrupted my studies to take part in an expedition on board the research ship "Meteor" for a year. At the time Fritz Möller and Heinrich Quenzel had initiated a project to study the absorption capacity of aerosols in the South Atlantic. This was a highly innovative topic back then. We carried out the research in the South Atlantic at 8°S because the atmosphere there had hardly been affected by man and only natural aerosols were present, apart from maybe soot from vegetation fires in Africa. First, I helped to prepare a container lab in Munich, and then in a shipyard in Hamburg I installed the equipment and finally spent four months on board the "Meteor" using the interference-filter actinograph to perform measurements with Mr. Quenzel.

KlimaCampus: What do you think were the findings that started modern climate science?

Graßl: It was David Keeling's CO2 measurements taken at his weather stations at Mauna Loa on Hawaii and at the South Pole, which he set up in the International Geophysical Year, 1957. By 1960/61 it was clear that the CO2 levels on Hawaii follow a rising sawtooth pattern (natural seasonal change). It was observed that the concentration of CO2 in the air changed during the course of the year. However, at the time there were no international comparisons, and the absolute value was unreliable. Bert Bolin from Stockholm, a Swedish CO2 expert initiated "key comparisons", whereby different labs around the world investigated the CO2 content of local air samples. It was clear that CO2 was increasing and this led to the rehabilitation of Guy Stewart Callendar's theory of an anthropogenic greenhouse effect, which he had published in 1938 in the Quarterly Journal of the Royal Meteorological Society. The measurements also proved Svante Arrhenius´ theory dating back to 1896.

"By the early 50s, it was possible to demonstrate with models that doubling CO2 causes warming."

KlimaCampus: Nevertheless, there was still a lot of work to be done. What other factors were key in promoting climate science?

Graßl: A commission from the Academy of Sciences in the USA! The World Meteorological Organization (WMO) was organizing the first world climate conference in Geneva in 1979, because there was a need for concrete research into whether humans affect the global climate. The basis for the investigations was the radiative transfer equation developed in the 50s. Solutions to this equation using twice the amount of CO2 showed that it would become warmer. But because there was a lack of dynamic processes, many, including Prof. Hinzpeter, were skeptical. (Editor's note: Prof. Hans Hinzpeter, Professor at the University of Hamburg and director of MPI-M).

The turning point occurred by that conference. The US National Research Council (NRC) commission stated, "Using the best available models we estimate that an increase in CO2 concentration will cause mean global warming." They also referred to a magnitude with error bars. A world climate programme, including the well-known WCRP (World Climate Research Programme) was agreed upon, along with three other lesser-known sections.

KlimaCampus: Was it only concerned with the atmosphere at the beginning, or were oceans involved as well?

Graßl: From around the mid 80´s, the oceanographers were also involved. Beyond the WMO planning group in Geneva, there were project offices in particularly committed countries such as the USA, Great Britain, France and Norway. In Hamburg, we coordinated the well-known CLIVAR project for a few years, since Lennart Bengtsson at MPI-M was one of the initiators. As Director of the WCRP, I also advocated making cryosphere research global, as it is now in the Climate and the Cryosphere (CLiC) project. In the first of the WCRP projects, TOGA (Tropical Ocean Global Atmosphere), which ended in 1994, Mojib Latif was one of the founding fathers of seasonal forecasts.

As a young researcher, I was lucky that Hans Hinzpeter, whom I had met on board the "Meteor", gave me freedom to research and never tried to influence me. He just asked me quietly, "What's new?" In 1973, for example, I suggested measuring the "cool skin" on open seas, as well as the radiation flux - something that was new to science back then. Creativity isn't possible without scientific freedom. This also is true for the WCRP. A lot of money went into that programme. NASA paid several million dollars per year for modeling surface processes in the project "Global Energy and Water Cycle Experiment." Thereby climate research turned into "big science". In 1995, the individual funding agencies commissioned us to find out how much money was being spent on climate research. The result: around a billion dollars per year (not including satellites). However: money alone does not foster knowledge.

KlimaCampus: So the WCRP gave impetus to climate research turning into "big science"?

Graßl: Yes. Through the WMO, the WCRP had the support of all the weather services worldwide, and through the International Council for Science (ICSU) we had top-level scientists.

How did you become the director of the WCRP?

Graßl: My predecessor asked me to apply, and the president of the German Meteorological Service (DWD) supported this.

"Often, you only realize later on what you have set course for"

KlimaCampus: A time when important developments were initiated. That must have been fascinating...

Graßl: One is hardly conscious about such progresses at the time. Often, you only realize later on what you have set course for. That's also true for the founding of the German Climate Computing Centre (DKRZ) in 1987. At that time I was serving on a Federal Ministry of Research and Technology advisory panel. In Hamburg we also have to thank Mr. Lüst for the founding of the MPI-M and for selecting Mr. Hasselmann as its founding director. This was a decisive factor in Hamburg becoming a climate research center. And all this led to the current Cluster of Excellence, CLiSAP.

The power of his words:
Prof. Hartmut Graßl at the KlimaCampus's fall fest in 2009

KlimaCampus: What happened in the years after the MPI-M was founded and before CLiSAP existed?

Graßl: The founding of the ZMAW (Center for Marine and Atmospheric Sciences). This joint center of the university and the Max Planck Institute - closely linking up oceanography and atmospheric research - paved the way for CLiSAP. It's well known that the first application for a cluster that focused on biological aspects was turned down. Concentrating on the core competence, climate research was crucial to the success of the second application.

KlimaCampus: Now, these disciplines are making a comeback. Biology, geography, economics and social sciences - these are all a part of climate research. Is this distracting the focus? What do you think the future holds?

Graßl: Interdisciplinarity is what's important today. On the one hand you need people who "dig deep" into a particular subject, and on the other hand you need integrators who apply a more general approach. It's often difficult for one discipline to recognize the innovative work of another. The peer review of research results can sometimes be difficult, but when it comes to cooperating, those who are particularly good have fewer problems than others.

KlimaCampus: How can this problem be solved?

"We need more top-class scientist and an appropriate appointment policy"

Graßl: We need more high-quality social scientists, for example behavioral researchers, to shed light the on role humans play in climate change. The appointment policy is vital here.

KlimaCampus: What about the next generation of scientists - do we have the right students? Are they different today?

Graßl: Are you asking about BScs or PhDs? Doctoral candidates are good as a result of the SICCS and IMPRS graduate schools. SICCS is still growing, IMPRS has a high standard. As for students, the German ones sometimes show less hunger for success. Foreign students are often much more ambitious. The demographic change will help us even more in the future.

Committed to the next generation: Prof. Graßl presents the Köppen Award to Dr. Julia Pongratz from the Max Planck Institute for Meteorology in 2011

KlimaCampus: In other words: We need more social scientists and students with more drive. What else?

Graßl: ... to expand the topic. We have several global problems: climate change, demographic changes (not growth), severe threats to biodiversity, and upheavals and conflicts in undemocratic countries where young men make up a large part of the population (Egypt, Tunisia, etc.). These are important topics for social scientists researching global changes. We also have to do more for what C.F. von Weizsäcker called "global public policy". The credo is still the national state - just like after the Peace of Westphalia. The only counterexample to the national state's overemphasis on sovereignty is the European Union. But since our problems are global, they also have to be solved globally. That's why climate negotiations fail. The social scientists should intensify their research regarding this issue.

"I'm a fan of the European Union"

KlimaCampus: Do you follow climate negotiations? Why do things go wrong?

Graßl: I'm more optimistic than the media that despite all the difficulties, we'll be able to find a binding international public law that will abate the climate change caused by humans. Obama's latest speech on the subject contained some concrete measures, and there's already a timetable for Paris 2014. Who wants to see that fail? Mitigation measures, that state how much which country has to reduce its emissions and by when, haven't been set yet. That's important, but now we're back to the same old topic: Why are we afraid of giving up our sovereignty and competence to an independent higher authority? We Europeans have already done this through the EU. I'm a fan of the European Union! It's a unique human experiment: a new "community of states" that came into being peacefully without a war. People used to invade; now they politely knock on the door because they want to belong. That's completely unique.

KlimaCampus: Finally, what were the highlights of your career? Can you tell us about two or three of your greatest moments?

Graßl: Academically, I was most innovative during my time in Mainz (1971 to 1976). I discovered the water vapor continuum in the atmosphere, studied the ocean's "cool skin" and invented the "dirty cloud." In addition, communicating climate change for German Physical Society (DPG) in 1986 pushed me into the role of a ghostwriter for the presidents of the scientific societies. The DPG had written something that the German Meteorological Association (DMG) didn't like, and they wanted to see climatologists on the panel. Mr. Schönwiese and I then joined in and together with him, I was allowed to rewrite the memorandum for the presidents: "Warning of worldwide climate change caused by humans." The Ministry of Research and Technology at the time wanted to prevent its publication, but it took place anyway in March 1987. And I became a "media star".

KlimaCampus: Why did the ministry under Mr. Riesenhuber want to stop the publication?

Graßl: Because the report was said to be politically inopportune. I was extremely disappointed and thought I'd wasted my time. Professor Trümper (editor's note: Max Planck Institute for Astrophysics) called me and said that the brochure has to be published now, but has to be revised. But I didn't do this. Then it was published unchanged at the spring meeting of the DPG. Initially there was no notable response - except for that from Franz Josef Strauß!

As Bavarian Minister-President, he used the Federal Council to demand the government convene a scientific climate council (the predecessor of the government's Advisory Council on Global Climate Change (WBGU)). Mr. Hasselmann and I were members at the founding meeting. As agreement could not be reached, I was appointed chairman, as I was the youngest there. The committee was then affiliated with the research ministry that had wanted to prevent the publication of the report. We were then able to act and to make Germany become a pioneer in climate politics. That's still partly true today. From a purely scientific point of view, we're at the forefront of climate research, on a par with a few institutions in the USA, England, France and Switzerland.

Professor Graßl, thank you very much for the interview!

Interview by Ute Kreis (CliSAP) and Dr. Annette Kirk (MPI-M) from KlimaCampus Hamburg.

*1 "The Göttingen Eighteen" was a group of respected German atomic researchers (including the Nobel Prize winners Otto Hahn, Max Born and Werner Heisenberg), who in 1957 opposed nuclear armament, which was being discussed by Chancellor Adenauer and Franz Josef Strauß.