Tasked with studying climate change from the Victorian period onward, one researcher decided to bypass the tree rings method altogether, aiming instead to analyze a common tree product: paper. The advantage in studying paper is that, because paper is a mishmash of trees, it's like having dozens of trees at your disposal. And if you're studying newspapers, each 'tree' even has its own stamped date---all the better to make precise, decades-long climate comparisons.
It was this idea that led Dan Yakir, a biogeochemist at the Weizmann Institute in Israel, to enlist the help of the Boston Globe by sending him snippets of old newspapers dating back to 1872.
Yakir burned more than 100 Globe samples at 2,000 to 2,200°F in a super-oxygen-rich oven, letting the carbon in the paper combine with the oxygen to make carbon dioxide. He then measured the carbon from the exhaust and used a mass spectrometer to determine its isotopic composition, particularly a key marker of fossil-fuel burning, carbon-13, and compared with to carbon-12. In this experiment, he was piecing together the story of the air that the trees were “breathing in” by photosynthesis each year. When the ratio of carbon-13 to carbon-12 goes up or down in the atmosphere, so does the ratio in the trees. That’s what was reflected in the newspaper snippets. [Popular Science]
His findings reveal just what we'd expect: The levels of carbon increase over time. Because these results corroborate what we've known all along, this means that newspapers serve as a valuable record of climate change---a finding that gives many other scientists high hopes.
Steven Leavitt, who heads a tree-ring lab at the University of Arizona, says that the advantage to Yakir’s research lies in the “newspaper samples probably representing many trees perhaps over a wide area, thereby smoothing out variability associated with differences among individual trees.” [Popular Science]