Medieval wine tasting fills in gaps
By PAUL VOOSEN, Science.
Excerpt: When it comes to understanding the medieval climate of Europe, scientists face a daunting issue: Europeans loved to chop down their oldest and biggest trees. ...[making] it difficult for researchers to obtain records of tree rings, a standard paleoclimate tool, leaving gaps where most Europeans actually lived. ...climate scientists are now turning to a far more abundant historical resource: wine. Records of grape harvests found in the cellars and monasteries of Europe stretch back to the 1400s and can provide a powerful resource for teasing out past temperatures. “Compared with the average tree ring, it’s really excellent,” says Stefan Brönnimann, a paleoclimate scientist at the University of Bern. ...Several years ago, Brönnimann and co-authors showed that the date of grape harvests was an excellent indicator of past temperature in the growing season. Now, in a new study published last month in Climate of the Past, they’ve shown that another measure—the reported sweetness of grape juice before fermentation—can also chart temperatures. ...The expert sugar ratings continue to this day, though now with modern tools, and Brönnimann’s team found they similarly do a good job charting modern-day global warming. Starting around the late 1980s, ratings of sugar content began to rise steeply, to the point where the record resembles the famed “hockey stick” spike in global temperature records. ...Studies suggest excessive drought and frequent heat waves could eventually kill off vineyards, especially in southern Europe. But for now, global warming has been good for European wine harvests, Brönnimann says. “From 2003, it’s been just good years.”