Washington, Nov 27 : Scientists have found that the amount of fossil-fuel-derived carbon dioxide (CO2) in the air over the vineyard can be measured in the wine's alcohol.
According to a report in Discovery News, researchers propose using the technique to track attempts to reduce carbon dioxide emissions in a given region, to see which carbon-management schemes work best, or to refine regional models of climate change.
The approach measures the amount of the radioactive isotope of carbon, carbon-14, which is created by cosmic rays high in the atmosphere.
This isotope represents a small proportion of the carbon atoms in the CO2 in the atmosphere, and is taken up by plants as they grow.
Over time, carbon-14 decays into the isotope nitrogen-14. Fossil fuels, made from plant material that lived hundreds of millions of years in the past, have no remaining carbon-14.
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.
Sanne Palstra of the Center of Isotope Research at the University of Groningen in the Netherlands, 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," Palstra said. "I could really see very clearly the proximity of industries or an airport. In that sense, it's a quite a sensitive method," she added.
According to Palstra, by analyzing the vintages of different years, "you can look back in the atmosphere by measuring wines."
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 said.
"It's going to become more and more important to develop these techniques to measure carbon dioxide from fossil fuels in surface air so we can diagnose regional fossil fuel emission reductions," said Jim Randerson of the University of California, Irvine. "This could be a really valuable component of a new network," he added.