In memory of Henrik B. Clausen

Asoc. prof., Henrik Brink Clausen died 23rd August 2013.

Henrik was born in the city of Ribe in 1937, and after high school he began his studies as engineer in chemistry in Copenhagen. Just after he finished his degree in 1962, he was hired by prof. Willi Dansgaard to develop methods for chemical extraction of carbon from CO2 from air bubbles in glacier ice and silica from the ice to determine the age of the ice by radioactive counting of 14C and 32Si. Henrik participated in Dansgaards expedition to Norway in 1963 where they tried to blow off chunks of a glacier with TNT. Later he participated in expeditions to Hintereisferner in Austria and to EqipSermia and Camp Century in Greenland. At EqipSermia, Henrik worked together with Bernhard Stauffer and a lifelong friendship developed. Henrik worked very hard at sample collecting at Camp Century. Here is an excerpt from Willi Dansgaards diary, Wednesday 29thjuly 1964: “In the middle of the night Henrik started yelling at the people who the day before had cut snow samples right down into our faces: “Can’t you throw all that snow somewhere else, gentlemen?” I turned on the light and asked what was wrong. “They are throwing a lot of snow into my bed!”, “Do you have snow in your bed?”, I asked. “Yes, my bed is full of snow and there is hardly room for me anymore!”, “Maybe you should just quietly lie down and sleep again”, “Yea, maybe I should – damned it” – and he did”

When WilliDansgaard in 1967 began his collaboration with Chester Langway on analyzing stable isotopes on the CampCentury ice core in the U.S., he had a group to support him in the task: Henrik Clausen, Sigfus Johnsen and Claus Hammer. Henrik spent weeks in the cold room at CRREL in Hanover, New Hampshire cutting samples. Here Henrik developed a lifelong friendship with Chester Langway which continued when Chester moved to Buffalo. In Buffalo, New York, Henrik met Hitoshi Shoji who also became a dear friend. Through his work in the U.S. he became a central figure in creating the first ice core based climate curve. So although WilliDansgaard gave birth to ice core research as we know it, Henrik was there as a midwife.

It turned out that it was easier to determine the age of ice samples by model calculations and counting seasonal variations of the stable isotopes than by radioactive methods. However, there was a lack of independent means to confirm the dating. Henrik began to systematically collect ice samples and develop a chemical extraction for radioactive isotopes that fell on the ice caps following the nuclear bomb tests in the 50s and the 60s. The Geiger counters in Copenhagen now registered man-made radioactivity instead of radioactivity from silicon and carbon. Hundreds of samples were measured, and it turned out, that wherever you looked in Greenland, the snow layer of 1963 was far more radioactive than the others. The 1963-layer became a reference for all future dating work. Later, Henrik worked with Claus Hammer on the development of a method to determine the acidity of the ice, and they became the first to produce a calendar on volcanic eruptions based on acid layers in ice cores. Henrik was among the first to realize that although it sometimes was not possible to identify a specific eruption, the temporal pattern of eruptions must be similar between cores. During the rest of his scientific career, Henrik worked on counting annual layers and measuring the chemical composition of ice so that annual layer counts and volcanic fingerprinting could be combined to date the ice and synchronize different ice cores and in this minimize the counting error.

Henrik was modest and always kind and polite “at home” in dealing with students or colleagues. He did not like to be at the center of attention – he left that task to Willi Dansgaard. However you should not cross Henrik “in the field”. “In the field” he was not afraid to bluntly speak his mind. He detested the lack of thoroughness in field work. In the past, several generations of co-workers in the field have experienced the sharp tongue of Henrik, when work was not done in a thorough manner or when people’s behavior did not live up to “normal civilized standards”. He was at the center for establishing the Danish tradition that no matter how primitive the conditions were on the ice, you had to wash and put on suit and tie every Saturday to show yourself and your company that you had not “yet degenerated into the monkey stage”. As a camp leader, he was feared when he expressed lacking standards of hygiene at the toilets, lengthy and in great detail, at the dinner table. Despite that, Henrik was well liked by all participants.

Henrik had a unique memory, and he could remember details about ice cores like few others. History was his hobby, particularly the history of Rome. The Roman view on pleasures of life was very attractive to him, and he believed that some of the best lives ever lived on this planet must have been those of rich Romans in Toscany during the PaxRomanum in the vaning period of Rome of the 2nd and 3rd century. He knew his Roman emperors, and lots of students have felt his enthusiasm during ice core drilling when drilling through the layers from the roman period: “Now we are at Marcus Aurelius. Tomorrow we will reach Augustus, and in a few days, the republic and the wars with Carthage”. This historical insight gave his work with Claus Hammer and Walter Friedrichs yet another perspective when they in 1988 published an ice core based dating of the Santorini eruption at 1642 BC. This date sent tremors through the archaeological community working with the Minoan culture, as the date was about 150 years earlier than previous dates. However, ever since 1988 the date from ice cores has moved only a few years; but most recent Carbon-14 dates are now very close to the ice core date. 

Henrik will be particularly remembered for his efforts to introduce thoroughness in the work with ice cores. His efforts laid the base for procedures that now have a worldwide use in ice core science, and his thoroughness forms the backbone of the Copenhagen calendar on climate events of the past 60,000 years, which today is considered an international standard. He has trained several generations of young scientists at the Center for Ice and Climate in the art of “checking and checking and checking yet again” and to count annual layers.

For years, Hank has taught physics to hundreds of geologists and geographers, and he picked up the nickname “Isn’t that so”-Clausen. He continued teaching, until age and weak health hindered both teaching and research at the same time. He continued his research unabated.

Through most of his career has Henrik, or “Hank” as he was known in the field, been active in expeditions: Norway, Austria, EqipSermia and Camp Century in Greenland in the 60s, Milcent, Crete, Dye-3, Dye-2 and South Dome in Greenland under GISP and several sites in Antarctica under RISP in the 70s and in the 80s Dye-3, Camp Century, GRIP, Renland in Greenland and Byrd Station in Antarctica. In the 90s he went to GRIP, Hans Tausen and NGRIP in Greenland, until a coronary infarct in 1998 put an end to future field work. Although the infarct weakened his stamina he continued his scientific work, because there was nothing wrong at all with his head. He even managed to participate in yet another ice core drilling, this time from an underground glacier in the Dobsina caves in Slovenia. He continued working on ice core dating and synchronization, in collaboration with Bo Vinther, until his body in spring 2013 became too weak for him to continue.

Throughout his life Henrik Brink Clausen has done an extraordinary powerful effort for Danish ice core research from which we, at the Center for Ice and Climate, now benefit. He has had a great influence on the successes of the ice core group. His enthusiasm and systematic approach made him internationally respected. The good and positive attitude Henrik had, and his direct, dry and blunt humor often kept us going when things got tough. In recognition of his contribution to Danish research he received the medal of the Dannebrog order, and he is one of the few Danes (perhaps the only one) who has a geographical location in Antarctica officially named after him: The Clausen-glacier in West Antarctica.

http://www.geographic.org/geographic_names/antname.php?uni=2850&fid=antgeo_105

We will miss him.

Henrik leaves behind his wife, Lone, their three sons: Jens, Lars and Mads, daugters-in-law and six grand children.

HONOR TO THE MEMORY OF HENRIK BRINK CLAUSEN.

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