Willi Dansgaard (30 August 1922 – 8 January 2011) was a

Danish Danish may refer to: * Something of, from, or related to the country of Denmark People * A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark * Culture of Denmark * Danish people or Danes, people with a Danish a ...

paleoclimatologist Paleoclimatology (British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important to ...

. He was Professor Emeritus of Geophysics at the

University of Copenhagen The University of Copenhagen ( da, Københavns Universitet, KU) is a prestigious public research university in Copenhagen, Denmark. Founded in 1479, the University of Copenhagen is the second-oldest university in Scandinavia after Uppsala Unive ...

and a member of the

Royal Danish Academy of Science and Letters {{Infobox organization , name = The Royal Danish Academy of Sciences and Letters , full_name = , native_name = Det Kongelige Danske Videnskabernes Selskab , native_name_lang = , logo = Royal ...

, the Royal Swedish Academy of Sciences, the Icelandic Academy of Sciences, and the Danish Geophysical Society.

Early life and career

Dansgaard grew up in Copenhagen, to parents who owned an

engraving Engraving is the practice of incising a design onto a hard, usually flat surface by cutting grooves into it with a burin. The result may be a decorated object in itself, as when silver, gold, steel, or glass are engraved, or may provide an in ...

shop. In 1947, he graduated from the

, winning a gold medal for his thesis on X-ray

dosimetry Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingested ...

. After several years of research, including some at sites in

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...

, Dansgaard returned to the

's Biophysics Laboratory, where he developed its

mass spectrometer Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a '' mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is us ...

to analyse water

isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

. According to his student Jørgen Peder Steffensen:

In June 1952, Dansgaard made a discovery that came to influence the rest of his scientific career. He discovered that it was possible to determine the temperature of the precipitating clouds by analysing the stable isotopic composition of rain water. In the following 12 years, he systematically collected water samples from all over the world in collaboration with the Danish East Asia Company, contacts in Greenland, a French expedition under Paul Emile Victor and later the International Atomic Energy Agency and
World Meteorological Organization The World Meteorological Organization (WMO) is a specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology and geophysics. The WMO originated from the Intern ...
.

Overview

Dansgaard was the first paleoclimatologist to demonstrate that measurements of the trace isotopes

oxygen-18 Oxygen-18 (, Ω) is a natural, stable isotope of oxygen and one of the environmental isotopes. is an important precursor for the production of fluorodeoxyglucose (FDG) used in positron emission tomography (PET). Generally, in the radiopharmaceu ...

and

deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one ...

in accumulated

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

ice could be used as an indicator of past climate. Dansgaard was the first to note deuterium excess, or a water sample's deviation from the global meteoric water line (GMWL) in ice cores. He found that the kinetic differences between

hydrogen-1 Hydrogen (1H) has three naturally occurring isotopes, sometimes denoted , , and . and are stable, while has a half-life of years. Heavier isotopes also exist, all of which are synthetic and have a half-life of less than one zeptosecond (10� ...

and deuterium related to the temperature of source water, and the absolute humidity. He was the first scientist to extract palaeoclimatic information from the American

Camp Century Camp Century was an Arctic United States military scientific research base in Greenland. situated 240 km (150 miles) east of Thule Air Base. When built, Camp Century was publicized as a demonstration for affordable ice-cap military outposts ...

ice core from

drilled by the US army

Cold Regions Research and Engineering Laboratory The Cold Regions Research and Engineering Laboratory (CRREL) is a United States Army Corps of Engineers, Engineer Research and Development Center research facility headquartered in Hanover, New Hampshire, that provides scientific and engineering ...

(CRREL). Dansgaard also took a leading role in the drilling of the first ice core to bedrock for scientific reasons, the DYE-3 core from

South Greenland The Southern Inspectorate of Greenland also known as South Greenland was a Danish inspectorate on Greenland consisting of the trading centers and missionary stations along the southwest coast of the island. Its capital was at Godthaab (modern N ...

, from the Camp Century. Confirming findings from the analysis of the Camp Century ice core, the DYE-3 climate profile documented the existence of rapid climate change, during and at the end of the last glacial. The repeated events of

abrupt climate change An abrupt climate change occurs when the climate system is forced to transition at a rate that is determined by the climate system energy-balance, and which is more rapid than the rate of change of the external forcing, though it may include sud ...

during the glacial are named after Willi Dansgaard and his Swiss colleague, Hans Oeschger, and are known as Dansgaard-Oeschger events.

Awards

* 1971 Hans Egede Medal * 1975

Swedish Society for Anthropology and Geography The Swedish Society for Anthropology and Geography (SSAG; sv, Svenska Sällskapet för Antropologi och Geografi) is a scientific learned society founded in December 1877. It was established after a rearrangement of various sections of the Anthropo ...

Vega medal The Swedish Society for Anthropology and Geography (SSAG; sv, Svenska Sällskapet för Antropologi och Geografi) is a scientific learned society founded in December 1877. It was established after a rearrangement of various sections of the Anthropo ...

* 1976 Seligman Crystal from the

International Glaciological Society The International Glaciological Society (IGS) was founded in 1936 to provide a focus for individuals interested in glaciology, practical and scientific aspects of snow and ice. It was originally known as the "Association for the Study of Snow an ...

* 1995 Royal Swedish Academy of Sciences

Crafoord Prize The Crafoord Prize is an annual science prize established in 1980 by Holger Crafoord, a Swedish industrialist, and his wife Anna-Greta Crafoord. The Prize is awarded in partnership between the Royal Swedish Academy of Sciences and the Crafoord Foun ...

* 1996

Tyler Prize for Environmental Achievement The Tyler Prize for Environmental Achievement is an annual award for environmental science, environmental health, and energy. Tyler Laureates receive a $200,000 cash prize and a medallion. The prize is administered by the University of Southern Cal ...

1996

Notes

External links

Chester C. Langway and Hans Oeschger
- Dansgaard's 2005 autobiography "Frozen Annals, Greenland Ice Sheet Research"

"Carbon Dioxide Through the Ice Ages' from UCSD (archived 2004)

"History of Danish ice core research" from Niels Bohr Institute (archived 2009)
1922 births 2011 deaths Danish climatologists Paleoclimatologists Members of the Royal Swedish Academy of Sciences {{climate-bio-stub