Higher temperatures provide more energy to move the lighter form of oxygen from water to vapor, and lower temperatures mean more of the heavy form of oxygen stays in liquid. This was bold thinking—if Dansgaard was correct, then the ratios of the heavy and light forms of oxygen in water might serve as a thermometer to indicate ancient temperatures in a sample of liquid water or ice.
Willi Dansgaard was born in 1922 and trained in physics at the University of Copenhagen.
