Interview with Carl Christian Wallén

Carl Christian Wallén —known to his friends as CC— was born in Stockholm on 17August 1917. It was through the efforts of his father, Axel Wallén, that the Hydrological Bureau (of which he was Director) merged with the Meteorological Institute to become what we now know as the Swedish Meteorological Hydrological Institute (SMHI). Axel Wallén was its first Director-General.

His father's sudden death left the family in financial difficulties. CC had not yet finished school, and it was thanks to the intervention of family friends that he was able to continue his studies.

At university, CC studied geography under Prof. Ahlmann. After graduation in 1940, his first full-time job was at the SMHI and he was fortunate to have Prof. Tor Bergeron as his supervisor and friend. During the academic year 1946-1947, CC went to Chicago on a special fellowship to study meteorology: the magnet which drew him and many other famous meteorologists there was Prof. C. G. Rossby. Back in Sweden, CC obtained his Ph.D. in 1949, becoming Assistant Professor at the university in 1950. That same year, he embarked on his career in international activities, which has continued ever since. In Mexico in 1954, while on a technical cooperation assignment for UNESCO, he met a young mathematician called Julian Adem. At CC's instigation, Julian went to Sweden to study meteorology with Rossby, and worked closely with the great man for several years before going to the USA to work with Jerome Namias in the field of long-range forecasting. (Julian Adem subsequently became Director of the Geophysical Institute in Mexico and is today Director of the Centre for Atmospheric Sciences at the National University of Mexico.)

CC became Deputy Director-General of SMHI in 1963 under Alf Nyberg and carried out various assignments for WMO, including a Special Fund project in Peru.

In 1968, CC accepted a post in the WMO Secretariat in Geneva. Although his daily duties covered a wide range of scientific fields, his main interests were climatology, applications of meteorology and the socio-economic aspects of climate change. His involvement in the environmental aspects of meteorology was inevitable: he played an important role in the organization of the UN Conference on the Environment (Stockholm, 19721) and from 1976 to 1980 was the main liaison officer between WMO and UNEP.

CC was executive editor of the famous Swedish scientific journal Tellus (1947-1953); regional editor, Agricultural Meteorology (1963-1973); and editor, European volumes, World Survey of Climatology (1966-1977). He was president of numerous societies in Sweden and was vice-president of the WMO Commission for Climatology from 1960 to 1968. He has participated in many international meetings and is the author of many technical and scientific papers dealing with climate changes, rainfall, acid rain, agriculture, agroclimatology, etc.

Dr Taba first met C.C. Wallén as a young meteorologist training at SMHI in October 1950 and recalls that, as a bachelor, Dr Wallén was extremely popular with the young ladies of the Institute! He married in 1959 and a daughter was born in 1960. Unfortunately, Mrs Wallén died unexpectedly in 1981. We would like to thank CC for according us this interview, which took place in Geneva in December 1991.


H T. — Please start by telling readers where you were born and something about your family.

C.C.W. — I was born in the summer of 1917, in Stockholm, to which my parents had moved from Gothenburg. This was during the First World War, and food was scarce because, although Sweden was neutral, surplus supplies had been sent to Germany during the first years of the war and in 1917 there was little left. As a baby, however, this did not affect me and in pictures taken in 1918 I look quite healthy!

At the time of my birth, my father, Axel Wallén, was Director of the Hydrological Bureau in Sweden, which had been created in 1907. One of his achievements was to merge the Meteorological Institute, which had been created in 1873, with the Hydrological Bureau and he became Director-General of the two institutes on 1 January 1918. My mother was the daughter of a judge in Gothenburg. We were four children: I had an older sister and two younger brothers and I remember my childhood as being very happy.

H.T. — Your father must have been an influence in your scientific leanings: what course did your education take?

C.C.W. — I started school in 1923. After three years in a preparatory school, I went to a boys school in Stockholm, where I studied Latin and the classics as my father had done before me in Gothenburg. I have always been grateful for this as it gave me a broad grounding in the humanities which I would not have had in a school where only science was taught. I was never very interested in school, however, I always found it boring, l muddled through but never had very good marks, despite my father's influence and the fact that I read a great deal.

Sometime around 1923, my father and mother participated in a meeting of scientists from the Scandinavian countries in Gothenburg. Albert Einstein was invited and I remember them telling me that they had spent an entire day with him, sailing. I was only six years old at the time, but I have been fascinated by Einstein ever since and have a good collection of books by him and on him.

By virtue of my father's profession, I lived with meteorology and geography practically since birth. During the 1920s for example, my parents invited many famous scientists from both Sweden and other European countries to our house and my interest in science in general increased as a result. Sven Hedin, for example, was a famous explorer of Asia and Gerard de Geer was a professor of geology who developed the concept of Ice Age chronology. They were among the most well-known Swedish scientists of the time. There was also Prof. E. de Martonne, the French geographer, and Prof. Sydney Chapman, who was the president of the International Union of Geodesy and Geophysics (IUGG). (The IUGG held its assembly in Stockholm in 1930, and my father was the Secretary of the Organizing Committee.)

H.T. — What was your introduction to meteorology?

C.C.W. — As I grew older. I drew closer to the fields of geography and climatology. During my last two years at school time, from 1933 to 1935, we had to carry out a study on a chosen subject and write a short thesis. My father arranged for Anders Angstrøm, who was a subdirector of the Meteorological Institute, to assist me in my choice of subject, which was the study of solar radiation conditions in a closed forest stand. He gave me the necessary instruments and I made measurements at different times of the day of the incoming solar radiation in a forest in the Stockholm archipelago, where we had our summer house. Angstrøm presented the results of these measurements to the next meeting of the IUGG and they were published in the proceedings in 1935—my first scientific article!

H.T. — Did you have any other practical experience in the field?

C.C.W. - My last year at school, 1935, was a sad one: my father had a stroke in February and died. He was only 58. This was a great unexpected blow to the family but also for the meteorological community. He had been designated President of the International Meteorological Organization, the forerunner of WMO, that same year. His colleague and close friend, Dr  T. Hesselberg of Norway, became President instead.

That June, with the help once more of Dr Angstrøm, I began my first much-needed job as an observer at the oceanographic station on the island of Bornö, off the west coast of Sweden. The director was Dr Hans Pettersson, professor of oceanography in Gothenburg.

An assistant, who was considerably older than me (I was only 17) ran the station when Pettersson was not there. When I arrived, he immediately left the station to my care. As well as making certain observations and changing the paper on instruments every day, I had to check old salinity and temperature reports my first experience of working with climatological records.

H.T. — When you went to university, it wasn't to study meteorology, however?

C.C.W. — In the autumn of 1935 I went to Stockholm University to study geography with Prof. Ahlmann, head of the Geographical Institute there. The 14 years I spent in this institute constituted an extraordinarily interesting and fascinating period of my life. Prof. Ahlmann was an interested and helpful teacher. He had also been a good friend of my father's and I had known him as a child. I therefore had a very special relationship with him during the whole period of my studies.

From 1936 to 1942, l spent one or two months every summer as a stand-in observer at the Observatory of Riksgränsen in northern Sweden. Such thorough training in weather observations was a good basis for further studies in meteorology, but I continued with geography and, until 1939, when war broke out, physics and mathematics. I was called up for military service at the beginning of December 1939 and spent most of 1940 in northern Sweden in what was called "neutrality guard" — guarding Swedish neutrality. Nothing serious happened to us, which was just as well, because I don't think we could have done very much to stop an enemy! l returned to university in the autumn of 1940 and graduated in geography, mathematics and physics the following year.

H.T. — But you became a meteorologist nevertheless?

C.C.W. — That autumn, I started my first fulltime job within the Meteorological Service as First Meteorological Assistant. I realized, of course, that if I was to continue in the meteorological field, I would also have to study meteorology. Dr Tor Bergeron, who was Associate Professor at the University of Stockholm and examiner in meteorology (there was as yet no full professorship), was also First State Meteorologist at the Meteorological Service. I worked closely with him, often as his assistant forecaster, at the same time as I was studying. In 1943 I took my exam in meteorology—a rather severe one—with a written part from 8.00 a.m. to 5.00 p.m. and a one-day oral examination. A severe examiner, Tor Bergeron was a fascinating and gifted person, who had been one of the leaders of the Bergen school in the 1920s. He, his wife and I became close friends.

In 1943 I was employed full time as a meteorologist by the Meteorological Service in the forecasting section of the airport and in the general forecasting section. I also worked in the climatological section on temperature and precipitation reports, which I had to examine one after the other to make sure that no temperature had been registered during the day that was higher than the maximum or lower than the minimum-an incredibly boring job.

Luckily, however. I shared an office with Gøsta Liljequist, who later became professor at the University of Uppsala, and who was similarly bored. We were both engaged in some scientific work in which we were much more interested but as this was not allowed during working hours, we had to hide it and only bring it out at suitable moments.

H.T. — How large was the Meteorological Institute in those days?

C.C.W. — At the time of my father's death in 1935, I think the staff numbered between 30 and 50. His successor. Slettenmark, was a most economical man. When I joined the Service, he called me in and welcomed me and said that he had recently lowered the salaries of the meteorologists by one grade as he felt young people would learn to manage their financial resources better if they had less money. As a result of that sort of approach, meteorology in Sweden did not progress much during his time. One of those opposed to the slow development was the president of the Staff Association, Alf Nyberg, who later became President of WMO. He started campaigning to improve the situation and eventually the Government arranged for a general overview of the Meteorological and Hydrological Service and its structure was changed slightly in 1945.

The original structure had a meteorological bureau and a hydrological bureau, each with a director and the general director at the top. In 1945, the name of the Service was changed slightly and the chiefs of bureau were promoted. In addition, special non-academic courses for meteorologists (Class 2) were introduced in order to increase the number of forecasters for the expanding civil aviation. A little later, in 1946 or 1947, the Government requested Professors Ahlmann and Norinder (professor of thunderstorm studies in Uppsala) to undertake an academic review. Their proposal was that Prof. Carl G. Rossby, who had been in the Service in the early 1920s prior to becoming professor at the University of Chicago, should be brought back to Sweden to stimulate the development of meteorology.

H.T. — In the meantime, however, you came to know Prof. Rossby in Chicago, I believe. This must have been a most stimulating time. What persons and events stand out most in your mind?

C.C.W. — Prof. Rossby returned to Sweden in 1947 but I had been granted a special fellowship to study under him in the USA for the academic year 1946-1947. This was probably the most remarkable and outstanding year of my life. After the war, almost all well-known meteorologists went to Chicago to study with or to see Prof. Rossby. To meet them all during that year was a unique opportunity. First of all, I and a few others, stayed with Prof. Erik Palmén from Finland. Later, I moved to the International House at the University of Chicago.

We were a large group of Scandinavians and had an enormous amount of fun during our leisure time, in addition to fascinating work in the Department of Meteorology, under the leadership of Carl Rossby. I remember in particular the first theoretical analysis of the “jetstream" by Erik Palmén at the beginning of February 1947, which he presented during a discussion of the synoptic situation. He had made a cross-section of a jetstream and a lively discussion immediately developed. We had known since the war that something like a jetstream existed, because aircraft had had problems of terrific winds at heights of around 8,000 m, but its existence had not been demonstrated by observations before. The question then arose of what the phenomenon should be called. I think it was Carl who suggested the name "jetstream". That was just one of many historical events that winter.

Many students in the department that year subsequently became famous. Jule Charney, for instance, received a fellowship to go from Los Angeles, where he had just finished his doctorate, to study in Norway. Carl heard about his going and sent a cable to Charney asking him to stop over in Chicago on his way to Norway. He accepted and stayed for a whole year. Charney and Rossby had a special friendship. Theoretical ideas that were later developed by Charney and made him famous for the development of numerical forecasting were first outlined during that year. Dr Alf Nyberg was one of the research workers.

Other people I remember during that fascinating year were of course the teachers we had: Victor Starr, Herbert Riehl and George Cressman. Among the students I remember particularly Rolando Garcia from Argentina and my close friend Tu Chen Yeh from China. With him I carried out a climatological study of the rainfall conditions in Hawaii for cultivating pineapple. While in Chicago, I concentrated on upper-air observations and aerology in general studies. Although my stay was short, the training I received was invaluable.

H.T. — What did you do upon your return to Sweden?

C.C.W. — I had to return to Sweden to finish my doctoral thesis on which I had been working with Prof. Ahlmann. A geographer, he had already made important studies in glaciology in the 1920s and 1930s and had suggested that l make study of a small glacier in northern Sweden, called the Karsaglacier, and I had already spent several summers in field work there from 1942 to 1946. I spent the summer of 1948 on the glacier and in the spring of 1949 I defended my doctor's thesis. My examiner was Prof. H. U. Sverdrup, who had been Director of Scripps Institution in La Jolla, but who was also a specialist on the problems of the heat balance at snow and glacier surfaces. He had spent a summer in Spitsbergen with Ahlmann in 1934, where their pioneering studies of the heat balance of a glacier surface, constituted the basis of my studies on the Karsaglacier. The difference was that Sverdrup had studied a flat glacier surface on the Isachsens plateau in Spitsbergen, while my glacier was in a sloping valley, where katabatic winds ran frequently along the surface and complicated the situation considerably. I had met Sverdrup in the USA and he had given me a considerable number of suggestions for my thesis but he was a tough examiner. A number of famous meteorologists were present, including Carl Rossby, Hans Ahlmann, Tor Bergeron, Hermann Flohn and Alf Nyberg. I felt very small, I must say. In the autumn of 1950, I became Assistant Professor in physical geography at the university, in which capacity I lectured and examined until 1954, at the same time as being First State Meteorologist at the National Meteorological Service.

H.T. — It must have been about this time that you started to become involved in international aspects of meteorology?

C.C.W. — WMO was founded in 1950 and one of the first small committees that had been established was for the development of telecommunications within Europe. I was first given the task of represent the Swedish Government at a meeting of this committee in 1952. We met in Paris under the leadership of a British meteorologist called Ockenden. That meeting lasted only for a week, but as I was already in Paris, I was also charged with another meeting, which lasted much longer, namely the ICAD European Regional Air Navigation meeting to discuss meteorological services to aviation during the 1950s. There was no simultaneous interpretation and the meeting lasted three or four weeks, with most sessions going on until 2.00 and 4.00 a.m. I enjoyed my first experience of an international meeting tremendously. One of my briefs was to have the standard time for the transmission of meteorological information to aircraft changed from three to five minutes. Several countries had only recently introduced three minutes and a change would have been costly for them. I remember having arguments with Ramses Mikhail from Egypt, with whom I have since had a very close friendship, both in WMO and UNEP. I was not successful, but the change was agreed on some three years later.

H.T. — Did you see much of Rossby during that time?

C.C.W. — I spent a good part of my time with Carl Rossby every day in his office to discuss contributions to Tellus, the journal of the Swedish Geophysical Society, which he had launched in 1948 and of which I was the executive editor and he the editor. I came to know Carl very well indeed and there are few persons whom I have admired more in my life. He was a high achiever but extremely kind—a rare combination.

H.T. — I believe it was at Rossby's instigation that you went to Mexico?

C.C.W. — One day, in the summer of 1953, Rossby received a letter from UNESCO, which, for some reason, he opened (he usually didn't open letters, but put them away in drawers, saying it was surprising how rapidly they went out of date!). The letter asked Prof. Rossby to suggest somebody for a technical co-operation assignment in Mexico. He asked me if l would like to go. I said I thought it would be fun and Carl sat down and wrote back to UNESCO immediately.

When I arrived in Mexico towards the end of January 1954, I was met at the airport by the President of the University, Dr Nabor Carrillo, who told me that I would be working with the Institute of Geophysics for the first period of my stay.

l spent several months developing the project and was eventually given three rooms in the university building and enough money to recruit two meteorologists and one secretary.

A young fellow called Julian Adem was working at the institute when I arrived. He had a doctorate in applied mathematics from Brown University in the USA. I suggested that he should go to Stockholm to study meteorology with Prof. Rossby. Julian stayed two years and as they were both interested in the mathematical aspects of meteorology, became good friends. Julian Adem subsequently became director of the Institute of Geophysics in Mexico and he is now (as I had hoped) director of the small institute that we established during my mission in 1954. It is now a university institution with more than 75 employees and handles both the theoretical and practical aspects of meteorology.

I enjoyed my stay in Mexico very much but had to leave at the end of 1954. UNESCO sent new man to continue the mission, whose name was Dr Fournier d'Albe, who was a geohysicist rather than a meteorologist. He was articularly interested in the rain-stimulation activities of the Institute. He stayed in Mexico until1960, when he joined UNESCO headquarters in Paris.

H.T — What precipitated your return to Sweden?

C.C.W. — I was offered the post of Assistant Director of the Swedish Meteorological and Hydrological Institute when Dr Angstrøm retired and Dr Nyberg became Director-General. I was chief of the Meteorological Bureau until 1960, when the Institute was reorganized to include a climatological bureau, of which I was director until 1968. As of 1963, I was also Deputy Director General of the Institute.

H.T. — Did you remain in Sweden all this time?

C.C.W. — In 1961 I was offered another interiational mission by WMO, namely to go to FAO n Rome to work on an agrometeorological project together with a staff member of FAO, M. Perrin de Brichambaut, a French specialist in agricultural ecology. The project was to carry out a one-year study of the meteorological conditions for agriculture in the Near East. This was an extraordinarily interesting task and l must say that, professionally, it was the most rewarding of any I have done. Agrometeorology in the developing world was a virgin area at the time and we had to invent most of the ideas of how to manage such a study in an area with few data. The countries concerned were Iran, Iraq, Jordan, Lebanon and Syria. By the end of March 1962, we had more or less finished the job and I had to go back to Stockholm.

H.T. — Can you describe the project and tell us something about its results?

C.C.W. — We concentrated on a rather new aspect of agricultural meteorology, namely the water balance in the area, which was fundamental as the region had a semi-arid climate. The studies made at the end of the 1940s by Prof. Penman in the United Kingdom and Prof. Thornthwaite in the USA formed the basis for our work. These studies demonstrated how plants develop under various water-balance conditions, an approach which had never been used in this region before. We divided the whole area into subregions and considered the water-balance conditions in each one. This was a difficult task as, in most areas, we had a maximum of 10 years of data that could be used. For the purpose of studying these countries, of course I also had to visit them: firstly in order to find out what kind of information and data were available and secondly to advertise the results of the study an get people interested in applying them.

The report was initially published as a technical report of several hundred pages, which gave all the details of the results of the study. It presented the meteorological and agricultural conditions in the area and went on to outline new ideas about how meteorological or climatological data should be applied to agriculture. Later, a slightly shorter version of the study was published in the WMO Technical Note series and became, I believe, something of a best-seller.

H.T. — Were the findings followed up by the countries concerned?

C.C.W. — The results were applied in all the subregions, notably in Iran and Syria, both by the Meteorological Services and by agricultural research institutes in, for example, their approach to seeding and harvesting times, when climatological statistics are useful for establishing optimum dates. In the 1960s, the countries were assisted in this work by WMO experts and, later, their own personnel.

H.T. — What did you do after that year in Rome?

C.C.W. — I returned to my post in Stockholm, where my work was of two kinds. First of all, I had the work at the institute where I had to apply computer methods to climatological data for the first time. I had great difficulty convincing my colleagues of the necessity of accepting modern techniques.

Secondly I was very much involved in other activities related to Swedish scientific societies. In the beginning of the 1960s, I became regional editor for Europe of a new journal that was launched by Elsevier in the Netherlands called Agricultural Meteorology. At the same time, I was also Editor of Geografiska Annaler, a publication of the Swedish Society for Geography and Anthropology, which had been issued since about 1920. I was also president of that society in the years 1960-1962. In 1960,l also became Secretary of the National Committee for Geodesy and Geophysics in Sweden, which was the centre for activities under the IUGG. At the same time, I was increasingly being requested to participate in international fora. l represented Sweden in both the WMO Commission for Climatology (of which I was vice-president from 1960 to 19681 and the WMO Commission for Agricultural Meteorology.

H.T. — In 1964 you took up a WMO assignment to Peru. What can you tell us about that project?

C.C.W. — The Director of the Technical Cooperation Department in WMO, Dr Sebastian, called me to discuss the possibility of becoming project manager of a Special Fund project n Peru. I agreed on the condition that I would go for half a year in 1964 and for another half a year in 1965. The assignment was staggering: the establishment of 700 meteorological and hydrological stations around the country and a hydraulic laboratory for testing hydrological instruments. The meteorological, agrometeorological and hydrological stations were to be established by experts from WMO and the hydraulic laboratory by the United Nations.

When I arrived in Lima in January 1964, about 200 stations had been established; a year later there were 500. By the time we ended the project in May 1965, the goals had been achieved, at least on paper. In reality, of course, some of these stations were not running well and some not at all— this would have been impossible in the time allotted— but we had good instrumentation and the hydraulic laboratory had been inaugurated and was in place. Dr Parthasarathy, who was Dr Sebastian’s deputy, came to Lima and we had a celebration to close the project in late May 1965.

That was the end of my mission.

H.T. — What are the most significant climatic characteristics of Peru?

C.C.W. — The Peruvian climate is extremely implicated, which is why so many stations were foreseen under the project. There are two completely different climatological regions: the arid desert areas along the coast, and the wet areas of the Andes which have snow —on the Sierra Blanca— as well as fertile slopes down to the rain forests in the Amazonian basin. Moreover, in an El Niño event, the cold water of the Humboldt current, which runs northwards along the Peruvian coast to the Equator, and carries enormous amounts of fish, is replaced by a warm, southwards running current in which the fish cannot survive. In the 1960s, fish were the basis of the Peruvian economy. Whenever an El Niño event occurred, the fish disappeared and the economy collapsed.

H.T. — Have you visited any other countries in Latin America?

C.C.W. — I went to Geneva from July 1966 to February 1967 as a consultant in charge of setting up three new Special Fund projects in Latin America. One in Brazil was to establish upper-air stations in the north-eastern part, where rainfall conditions vary tremendously. The second project in the Caribbean involved establishing an improved service for hurricane forecasting and improved co-ordination between the small Services of the various islands. For the third project I visited the countries of Central America to launch a Special Fund project for the co-publication and co-handling of climatological data.

H.T. — And then you decided to accept a post in the WMO Secretariat?

C.C.W. — In 1967 I was offered a post in the WMO Secretariat and my director agreed to give me leave of absence from the Meteorologcal Service.

I arrived in Geneva on 1 April 1968 and took up the post of Chief of the Scientific and technical Division, which dealt with the work of our technical commissions: the Commissions for Climatology; Agricultural Meteorology; Atmospheric Science; and Instruments and Methods of Observation. The division had many responsibilities and a staff of 12-15. Dr K. Langlo was Director of the Technical Department and in charge of all the divisions. In my division, Mr G. Kronebach was directly in charge of the Commissions for Atmospheric Science and Instruments and Methods of Observation, so I was able to devote myself more to the other two.

The four years 1968 to 1971 were probably the busiest years I have ever had, because of the Organization's many new activities.

Congress in 1967 was perhaps the most forward-looking of all Congresses since the inception of WMO and allocated more money for new activities than any before or since.

H.T. — What aspect of meteorology interested you the most?

C.C.W. — A geographer originally, I had always been particularly concerned with the climatic aspects of meteorology and the application of meteorology and climatology to human activities and to socio-economic matters. Already in 1945, when I was in the Swedish Meteorological and Hydrological Service, immediately after the war, many rivers in northern Sweden were regulated, which had important impacts on the living conditions for the farmers who lived on their banks. Dr Angstrom had charged me with studying the impact of these regulations of the rivers on the local climate. This meant that I had to travel frequently to the northern part of Sweden and discuss with the farmers exactly what they considered to be local changes of climate (or environmental changes, as they have now come to be called). The one problem they all mentioned was the increasing frequency of fog. After study, we found that fog had indeed been increasing along the rivers, depending or how the river had been regulated, but it was dificult to establish from the statistics we had available. The next step therefore was to establish special stations in these areas to study the changes of climatological conditions. This was my first experience of an environmental problem cause by meteorological conditions.

H.T. — Acid rain must have been another?

C.C.W. — This became part of the problem of air pollution, on both local and larger scales. During the war, oil was extracted from the limestone in central Sweden. In the process, the area around the factory in question was completely destroyed by air pollution. But, even more interestingly, we could show in the 1950s that, because of the westerly winds over central Sweden, the emissions from that factory had been destroying photographic equipment in factories about 200 km away. That was my first experience of a problem of long-range transport of air pollution. In the following decade, air pollution problems became even more pressing, particularly in cities.

H.T. — One of your concerns, therefore, was to increase awareness of the environmental aspects of meteorology?

C.C.W. — The Swedish Meteorological Service pioneered studies of air pollution in cities and of how to plan cities in order to avoid pollution from industrial areas. A number of Swedish specialists who developed some of the first models for that purpose were Prof. T. Høgstrøm and Dr B. Bringfelt. When I came to WMO in 1968 I was reasonably well prepared and perhaps even more prepared than most to take up environmental problems.

One of my goals was to introduce environmental aspects into meteorology and into WMO. I was pleased therefore and fortunate that in 1968 the idea was launched of having an international conference on the human environment within the United Nations system to be held in Stockholm in 1972. As a result, the environment became not only a popular issue but a global one. It was not always very clear what "human environment meant but it was generally agreed that the most important part of the environment for the human being must be the physical environment. Mr Maurice Strong from Canada was appointed Secretary-General of the conference and Dr D. A. Davies, Secretary-General of WMO, who chaired ACC discussions on the envionment, was given the responsibility of preparing the conference on behalf of the UN. It was agreed that a committee should be set up with representatives from the specialized agencies having activities related to the human environment. This committee was established sometime in the beginning of 1970 and in the first few months I took the chair on behalf of Dr Davies. The representatives from the different agencies included Dr E. Saouma, then Director of the Land and Water Division in FAO, and in charge of problems of the environment, and who later became Director-General of FAO; Dr M. Batisse of UNESCO (he also developed the Man and Biosphere programme in UNESCO which was adopted in 1972); and Dr M. Kaplan from WHO.

The committee met every other month throughout the years of 1970 and 1971. We ended up with a comprehensive document which showed in detail what all the agencies were doing in the environmental field. It was too unwieldy, so we agreed to prepare an executive summary which would be approved by the ACC before presentation to the conference. This was difficult and time-consuming task as most agencies wanted to show that there was no need to create a new organization for the human environment. I accompanied Dr Davies to New York in November 1971 to present the draft summary to the ACC. That was my only experience of an ACC meeting and I was impressed by the UN Secretary-General U Thant, as being a noble and efficient leader.

H.T. — What were the arrangements for the conference and what was its outcome?

C.C.W. — Maurice Strong set up a small secretariat for the conference in Geneva, headed by Mr Peter Thatcher (who later became the first Regional Director of UNEP in Geneva), to which we delivered our documentation, particularly on atmospheric pollution problems, but also on climate. The conference was a success and the outcome of it led to the creation, not of a new specialized agency, but of the United Nations Environment Programme (UNEP), which co-ordinates all activities of the UN system in the environment field.

The UNEP Secretariat was established in Nairobi, Kenya, towards the end of 1973 (it had been stipulated at the Stockholm conference that it should be located in a developing country). Over the years, it has been active in the environment field, carrying out its basic functions as a catalyst and co-ordinator of environment activities within the UN system. The first Director of this programme was Maurice Strong. He was succeeded by his deputy, Dr M. Tolba, who has been Director since 1976.

H.T. — Meanwhile, you continued to work on environmental problems, especially the long-range transport of air pollution?

C.C.W. — Environmental problems became more and more critical as the 1970s progressed. At the Stockholm conference, Sweden had contributed a small booklet which showed that air-pollution problems were on a much larger scale than had previously been thought. It was not until the late 1960s that Dr S. Oden and other Swedish scientists were able to show that sulphur in the air could be transported over long distances and create acid rain, which could have very detrimental effects, particularly on lakes and rivers. Scientists in most other countries were convinced hat the impacts of air pollution could be avoided by building sufficiently high stacks in industrialized areas so that the pollution would disappear above the boundary layer. This is true enough for cities and industrialized areas but air pollution stays aloft and is often transported over long distances.

H.T. — This idea was not accepted internationally until much later, in fact?

C.C.W. — The European countries set about proving the existence of long-range transport of air pollution in western Europe through a project organized by the Organization for European Co-operation and Development between 1974 and 1976. The evidence was overwhelming. The main conclusion to be drawn from various studies during this period was that environmental problems such as acid deposition could be caused in one country through emissions which originated in another country. The issue was then recognized as one of the first trans-boundary environmental problems.

H.T. — But your compatriot Erik Eriksson was already working on the problem of acid rain in the early 1950s?

C.C.W. — Dr H. Egner and Dr A Ångstrøm pioneered the study of precipitation chemistry in the late 1940s and set UP stations around Ultuna in Sweden to determine what chemicals were transported to the soil. In 1952, Rossby realized the potential importance of atmospheric chemistry and asked the specialists in Ultuna if they had a young student with an agricultural background who could work on these aspects of meteorology at his institute. Erik Eriksson was selected and later became famous for his pioneering and fundamental studies in atmospheric chemistry.

H.T. — So Eriksson's work was the springboard for the establishment of the Background Air Pollution Monitoring Network (BAPMoN)?

C.C.W. — Erik introduced his and S. Oden's ideas on acid precipitation to WMO through the CAS working group on atmospheric chemistry, of which he was a member. This working group, which was chaired by Mr McCormick from the USA. considered which parameters it was necessary to observe and how to establish a network of stations to observe them. At a meeting in March 1969, it recommended to the Executive Committee that an international network of stations around the world should be established by WMO for studies of atmospheric chemistry. That recommendation was adopted as a resolution of the Executive Committee and the Background Air Pollution Monitoring Network was started in the second half of the same year-and this some three years before the Stockholm conference.

H.T. — How was BAPMoN structured and how has it evolved?

C.C.W. — The network comprised two differed types of station: the baseline stations, where measurements of carbon dioxide and other gases were made; and regional stations, where measurements were made of turbidity and precipitation chemistry.

In 1969 the Executive Committee also established a Panel on Atmospheric Pollution, whose chairman until 1976 was Prof. Christian Junge from Germany, a pioneer in atmospheric chemistry. He had started with studies of precipitation chemistry in the USA in the early 1950s by setting up a special network of stations on the eastern seaboard. He had often been to Stockholm for discussions with Erik Eriksson.

Every year I tried to get resolutions passed by the Executive Committee and Congress about establishing further BAPMoN stations in various countries. This was no easy task as most meteorologists did not understand the need to study air pollution and air chemistry. One member of the Executive Committee in favour of introducing atmospheric chemistry into WMO, who helped me prepare the resolutions for presentation to the Committee, was Prof. Yu. Izrael of the USSR. He was interested in the Hydrometeorological State Committee of the USSR becoming responsible for the natural environment and we worked closely together.

In 1974, the Executive Committee agreed that BAPMoN stations should not only make observations of pollution in air but also in freshwater, soil and biota, so that it would be possible to follow the transport of pollution from one medium to the other. That idea was launched by the USSR. Today we are working in UNEP on the question of monitoring polluants in several media at the same site. This is now called integrated monitoring and has become an important methodology for studying what is happening in terrestrial ecosystems as a result of the action of pollutants. It will also be useful for the study of changes in vegetation due to climate change.

H.T. — HOW would you define the environment?

C.C.W. — There are so many factors involved: physics, chemistry and biology, but also the social and economic environment. The environment of an area involves the sum total of the exchange and integration of the impacts from all factors. A basic problem in this context is the interrelationship between the physical and chemical factors on the one hand and the biological and ecological factors on the other. You may add the social and economic factors as part of the biological ones if you consider the human being as part of the biology and ecology.

I see the development of the IGBP (International Geosphere-Biosphere Programme) over the last 10 years as being a result of our gradual understanding of the need to study in depth the vital interrelationship between geophysics and biology.

H.T. — Do you agree with the idea that the atmosphere is the most important component of the environment?

C.C.W. — For the human being or for life in general, maybe the atmosphere is the most important. If you look at the environment from the point of view of how various aspects of life are interrelated: vegetation, wildlife, human beings, etc., its importance is not clear. For terrestrial ecosystems, the atmosphere is, of course, most important but, for marine ecosystems, the oceans are. Climate can be said to be the integrated environmental result of what happens in the atmosphere, I wish to emphasize that the issue of the environment can be separated into global, regional and local environmental problems.

Global environmental problems, such as climate change and depletion of the ozone layer, affect mankind as a whole and, in order to avoid global disaster, something must be done. Regional and local problems, however, are not caused by, nor do they always contribute to, global problems. They should not concern us in the same way as the global ones. In considering them, economic and social development must also be given high priority, especially in developing countries.

H.T. -How did your connection with UNEP come about?

C.C.W. — I think it was in 1976 that discussions started between Dr Davies of WM0 and Dr Tolba of UNEP about the possibility of closer liaison between the two organizations, which share many common problems and programmes. The idea was mooted that I would move to UNEP as Deputy Director of the Global Environment Monitoring System (GEMS). This was finally agreed and I moved into the new position but retained my office in the WMO Secretariat so as to ensure liaison between the two organizations. I found this change in my international professional life quite rewarding and the new contacts in various fields broadened my outlook. My chief in UNEP, the Director of GEMS, was an Italian doctor of medicine by profession, Francisco Sella, with whom I became aclose friend. He had earlier been Secretary of UNSCEAR in New York.

I stayed with UNEP for four years until 1980, when I retired. However, first Dr Sella and then Dr Michael Gwynne, who later became Director of GEMS, asked me to stay on as a consultant, which I have been doing for the last 10 years, at the same time as being advisor to Dr Tolba. The 1980s were an especially interesting time because of the new concern about climate and the increasing awareness that anthropogenic emissions of greenhouse gases into the atmosphere are a problem which affect every one of us and may lead to a global change of climate. This has became a major political issue: the question is whether to mitigate the threat by reducing missions or to adopt the "business as usual" philosophy in the hope that we will be able to adapt to the consequences.

H.T. — What are your personal views on climate change?

C.C.W. — My personal interest in climate change goes back all the way to 1939 when I attended a seminar at the Geographical Instiute in Stockholm organized by Prof. Ahlmann. The subject was the remarkable warming of climate in the northern hemisphere that began about 1900 and eventually lasted until 1950. Geographers were interested in this warming because of the considerable impact on the world's glaciers and ice-sheets. Famous meteorologists in Sweden attended, such as Prof. Ångstrøm, and Dr J. Sandstrøm, who had been a collaborator of Vilhelm Bierknes during the first decade of the century.

In 1954, I wrote a paper with Ahlmann in which we showed that the period of warming in the northern hemisphere had ended by around 1950. The climate of the northern hemisphere and most of the world then underwent a period lasting 20-25 years when there was a gradual cooling —even if not very strong— which lasted until the end of the 1970s. I think it is wrong, therefore, to state that there has been a gradual increase of temperature since the end of the last century. In fact, the period when the enhancement of the greenhouse effect is supposed to have been particularly marked, i.e. from 1950 to 1975, was a period when climate over the northern hemisphere cooled. Taking all the data from the end of the last century up to 1980 together is therefore not acceptable, as the fact that climate cooled during the period 1950-1975 cannot be ignored. There must have been two different causes for the two periods of warming, i.e. for the one from the end of the last century until 1950 and for the present one that started in 1975. There are still no clear indications that the warming in the first half of the century— which affected only the northern hemisphere— was due to an enhanced greehouse effect.

H.T. — If the introduction of greenhouse gases started at the end of last century, how long would it take for the effects to be noticeable?

C.C. W. — Most exiting data from the first half of the century are incorrect and cannot be used, so it is difficult to caIculate exactly what impact there was in that period. The increase of CO2 was small: we estimate that there was about 290 p.p.m. of CO2 in the atmosphere around 1880 and we know now that it was 315 p.p.m. in 1958, i.e. an increase from 1886 to 1960 (72 years) of 25 p.p.m. From 1958 we have very exact measurements from Hawaii and we know that from 1958 to 1990 (32 years) the increase was from 315 p.p.m. to 350 p.p.m., i.e. 35 p.p.m. Since the start of BAPMoN observations, the increase of CO2 has been confirmed at all baseline stations around the globe.

H.T. — What do you think might be the causes behind the two periods of warming?

C.C.W. — One hypothesis is that during the period 1900 to 1950 there was extraordinarily little volcanic activity around the globe. With normal volcanic activity, there is always so much dust in the Upper atmosphere that temperatures are kept down somewhat. Conversely, therefore, temperatures would gradually increase if volcanic activity were low for a long time. Volcanic activity started to become normal again in the 1950s, which coincided with the onset of a period of cooling.

That seems a reasonable explanation but it has not been proved. Volcanic activity since 1950 has been quite strong, just as strong as during the 19th century. Since the 1960s there have been many eruptions, including the Agung and El Chichón. Notwithstanding, it must be agreed that the greenhouse effect was being offset in some way, at least during the period after 1950. A complicated interplay must have been going on since 1975 between the forces causing warming during the first part of the century, those of the cooling during 1950-1975, and thos of the greenhouse effect.

H.T. — How would you like to see the problem of climate change tackled?

C.C.W. - During the late 1940s I tried to show what happened to the general circulation of the atmosphere in the mid-latitudes, in connection with a change of climate. In Stockholm in the early 1950s I worked with Dr Daniel Rex when he was preparing his doctoral thesis on "blocking" in the mid-latitudes. I have always argued that changes in climate should be possible to prove by studying changes in the general circulation of the atmosphere. It should, for instance, be possible to show more definitely what the impacts of the greenhouse effect are on the general circulation. Such studies are being carried out but there is not enough money invested in this kind of research. We can make studies of what is going to happen in 50 years by general circulation models but, without proof that some thing is already happening in the atmosphere due to the enhanced greenhouse effect, we will not be able to convince politicians to act. The modelling results concerning the future cannot be evaluated by data but what has happened over the last 15-20 years-with the upper-air circulation for instance-can be studied in more detail.

H.T. — Are you satisfied with the way climatology has developed?

C.C.W. — Of course, having been a climatologist since the 1930s, I am happy to see that climate has become such an extraordinarily important scientific subject, even an issue. There is nowadays great interest not only in climate change but also in climate itself. The impact of climate and climate variability on various economic sectors and its socio-economic impact are now being studied worldwide. Yet there was a long period during my career- until the 1970s, in fact-when the climate aspects of meteorology were completely neglected. This was basically because of the great needs of aviation for synoptic meteorology. Even as late as 1975, most climatologists were still dealing with classical climatology, i.e. adding figures and dividing by a number in order to obtain some sort of an average for a certain place, for a certain reason.

I had known Prof. H. Landsberg, who was president of the Commission for Climatolog, and the word's most famous climatologist, since the 1940s. We had many serious discussions about the neglect of climatology. Aroung 1974-1975, however, a number of modellers who had been concentrating on modelling for numerical forecasting became interested in applying this technique in climatology. Then came a breakthrough for modelling future climate, which has been quite successful over the last 15 years. Conversely, however, I am somewhat concerned that. today, too much of the classical climatology is being neglected. This is because climate was redefined so as to be able to use the deterministic approach of applying the dynamics of the atmosphere to future climatic development. As originally defined, climate is essentially a stochastic process, to which the application of deterministic methodology is not necessarily acceptable.

Whether a "climate" can really be obtained from a modelling approach —even if the model can be run over many years— is still doubtful and further study is necessary.

A general development about which I am pleased is man's realization that the climate surrounding him is an environmental problem of basic importance which must be studied and monitored carefully if mankind is not to suffer a long-term problem.

H.T. — How do you see the future of meteorology?

C.C.W. — The future of meteorology is difficult to foresee. Both WMO and the world's Meteorological Services are at a crossroads and I think it is extremely important to reconsider the structure and functions of WMO.

WMO must become functional at the ministerial level in the same way as other specialized agencies: if a Meteorological Service occupies a low position in a country's infrastructure, it is not in a position to influence government policy.

The question will gradually have to be considered whether there is a real need for national Meteorological Services of the present kind. It is more likely that there will be a need for regional Meteorological Services. We already have the technology for a few centres to do everything necessary for the whole world. At the national level, only Small services for local forecasting and application of climatology to various activities of the society will be needed.

H.T. — Will the meteorologists of the future be different from the meteorologists trained 50 years ago?

C.C.W. — They already are. Students are already no longer taught how to analyse synoptic maps. Satellite technology is still developing and will become increasingly important. It will have a revolutionary impact on measuring parameters at the Earth’s suface and meteorologists will have to learn new observation techniques. The UN, rather than individual countries, will probably have to accept responsibility for operating environmental satellites.

H.T. — Thank you very much CC. I hope we will continue seeing you around WMO and UNEP for many more years to come.



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