Saturday, January 29, 2011

Deceased--Willi Dansgaard

Willi Dansgaard
August 30th, 1922 to January 8th, 2011

What are the odds that we have drunk some T-Rex pee?

"Willi Dansgaard Dies at 88; Read Climates in Old Ice"


Douglas Martin

January 28th, 2011

The New York Times

It is said that every breath we take contains molecules breathed by Socrates, Jesus and Abraham Lincoln — a notable exception being the ancient air that the Danish geophysicist Willi Dansgaard and his colleagues found trapped deep in the ice of Greenland.

Drilling more than a mile through millenniums of ice, Dr. Dansgaard and a team of researchers journeyed backward through time to analyze trapped bubbles of air containing molecules of oxygen so old they had never been breathed by a human. By analyzing samples, they could gauge the world’s climate during various periods and determine how it had changed.

They found, among other things, that temperatures have changed more suddenly and violently than had long been supposed; around 15,000 years ago, for example, Greenland abruptly warmed by 16 degrees within 50 years. It had been thought that major climate changes occurred over thousands of years.

Perhaps more important, Dr. Dansgaard, who died this month, perfected ways to date icebound gases as well as to analyze acidity, dust and other influences on climatic conditions. Ice-core analysis proved to be a major advance in studying the climate history of the planet, providing evidence that predated other sources of measurement like tree rings, lake sediments and petrified organic matter.

In 1996, he was awarded the Tyler Prize, environmental science’s highest award, as were Claude Lorius of France and Hans Oeschger of Switzerland. Through his own ice-core analysis, Dr. Oeschger also discerned abrupt climate changes, which have become known as “Dansgaard-Oeschger events.”

Dr. Dansgaard’s work had significant implications in measuring carbon dioxide concentrations over vast periods and understanding the dynamics of global warming. One finding was that temperatures and so-called greenhouse gases, which trap heat, move in lockstep. In an interview, William Sweet, author of “Kicking the Carbon Habit” (2006), called this “the most compelling evidence we have of the relationship between greenhouse gases and global temperature.”

Dr. Dansgaard died on Jan. 8 in Copenhagen at 88, the Niels Bohr Institute of the University of Copenhagen said.

He was born in Copenhagen on Aug. 30, 1922, and received all his schooling there, including a doctorate in physics. He first went to Greenland in 1947 to study magnetism and was “bitten with Greenland for life,” he later said, citing “its forces, its bounty, its cruelty and, above all, its beauty.”

After returning to Denmark, he began using a machine called a mass spectrometer to weigh and identify oxygen molecules based on their number of neutrons. That led to an experiment to see if the hydrogen and oxygen molecules in rainwater changed from one rainfall to the next. He put funnels in beer bottles on his lawn to find out.

He discovered that as clouds rise and cool, heavier forms of oxygen (or isotopes — those with more neutrons) will react to the cold sooner, condensing and falling back to earth as precipitation before lighter ones do; a preponderance of heavier oxygen molecules would then indicate colder atmospheric temperatures. The discovery — that the chemical composition of oxygen revealed temperature — has been deemed Dr. Dansgaard’s most important.

He then obtained worldwide rain samples from the International Atomic Energy Agency, which collected samples to track radiation from bomb tests. He again found oxygen isotopes an excellent predictor of temperature and published a landmark paper on the subject in the journal Tellus in 1964.

To see if his findings might be confirmed in Greenland, he visited an American cold war outpost there, Camp Century, which had been set up to plan for possible nuclear attacks over the Arctic circle.

Scientists at the camp, who were studying numerous Arctic phenomena, many unconnected to military utility, were drilling into the ice to study how to differentiate one year of snowfall from the next. They agreed to let Dr. Dansgaard analyze ice samples, using the yearly snow measurements as a yardstick.

Wallace Broecker, the earth scientist at Columbia University who is often credited with introducing the term global warming, said in an interview that the importance of the mid-’60s ice-core work of Dr. Dansgaard and Dr. Oeschger did not immediately register on scientists except as “a curiosity of ice in Greenland.”

But after the drilling of another core from 1979 to 1981, interest skyrocketed. “This was astounding that you could get these temperature changes so rapidly,” Dr. Broecker said. He estimated that Dr. Dansgaard accelerated ice-core study by 10 years.

Dr. Dansgaard is survived by his children, Birgitte, Finn and Trine; six grandchildren; and one great-grandchild.

In his book, Mr. Sweet quoted Dr. Dansgaard as modestly suggesting that his seminal inspiration — that isotopes might be the key to learning the temperatures of past epochs — was his only good idea.

“It was in fact a brilliant idea,” Mr. Sweet wrote, “and for the rest of his working life, with growing crews of oarsmen at his beck and call, Dansgaard would pursue it with the obsessiveness of a Viking raider.”

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