Wine's Bouquet Has Overtones of Climate Change

Nov. 26, 2008 -- Among the complex mélange of molecules that create a wine's bouquet is another chemical signature: The amount of fossil-fuel-derived carbon dioxide in the air over the vineyard can be measured in the wine's alcohol.

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.

"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, who was not a part of the study. "This could be a really valuable component of a new network."

The approach offers an alternative to stations that measure CO2 directly, which are relatively scarce.

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"There are less than 10 measurement stations in the whole of Europe," said the study's lead author, Sanne Palstra of the Center of Isotope Research at the University of Groningen in the Netherlands. "If we want to say more about spatial and temporal variations in Europe, we have to increase the number of sites."

The approach measures the amount of the radioactive isotope of carbon, carbon-14, which is created by cosmic rays high in the atmosphere (and by nuclear explosions, which were a significant source in the mid-twentieth century).

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.