When fossil fuels are burned, the resulting CO2 is nearly carbon-14-free. So air with less carbon-14 in its CO2 carries higher amounts of fossil-fuel-derived carbon. This signature is carried through the plants as they use the CO2 to grow throughout the season -- and into the wine made from that year's grapes. Palstra and colleagues analyzed wine from different regions of Europe, distilling off the ethanol and measuring the amount of carbon-14. They compared the amount with a reference sample from a location in the Swiss Alps, far from any local fossil fuel emissions. "In northern Italy and in Germany, you could see there were more fossil fuel emissions," she said. "I could really see very clearly the proximity of industries or an airport. In that sense it's a quite a sensitive method." "You can look back in the atmosphere by measuring wines," Palstra added, by analyzing the vintages of different years. Palstra found that there was significant variation in a given location from year to year, which may represent effects from weather patterns. It will be important to include weather information in calculating the amount of fossil fuel CO2 in the future, she added. Measurements of wine ethanol would be limited to wine-growing regions, of course, but other plant material could be used as well. Randerson was part of a study that used the leaves of corn plants in the United States to look at the amount of fossil fuel carbon in different regions. "The European scientists know how to conduct their science in style," Randerson conceded. "Here in the U.S., we do it with corn. In Europe, they use wine." Related Links: |
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