Greenhouse gas leaves message in a bottle

16 December 2008

Bottles of wine contain a record of the carbon dioxide that we pump into the atmosphere, scientists have found. They hope that cracking open a few bottles will be a cheap way to monitor our CO2 emissions. Antenna samples this corking discovery...

Image: Andrew Johnson/iStockphoto

Carbon dioxide is naturally released into the atmosphere when animals and plants breathe, volcanoes erupt, and dead things decompose. Massive quantities of the gas are also released when humans burn fossil fuels to make electricity or power cars.
CO2 emissions from human activities are the main reason the Earth's climate is warming. Many governments are now trying to reduce CO2 emissions by burning less fossil fuel.

Image: Anna Pustovaya/iStockphoto

Climate scientists usually measure CO2 by collecting air samples. But the machines used to do this are expensive, and air monitoring stations are few and far between. This means there's little detailed local information on CO2 emissions for scientists to scrutinise.
Lutjewad in the Netherlands is one of only nine air monitoring stations in Europe.

Image: University of Groningen

A team of Dutch scientists realised that wine could offer a much cheaper way of keeping tabs on CO2 emissions. To test out their idea, the researchers uncorked 165 bottles from across Europe.

They analysed the carbon content of each vintage and compared it with readings from air monitoring stations.

Image: University of Groningen

What did they find?
'When the wine came from an urban area, like parts of northern Italy and Germany, this was clearly reflected in the results - we could see that fossil fuel emissions were much higher than in rural areas.' Sanne Palstra, environmental chemist

Sanne Palstra, University of Groningen, the Netherlands.

Image: University of Groningen

How is CO2 from fossil fuels recorded in a bottle of wine?
Grape vines take up CO2 from the atmosphere and turn it into sugar during photosynthesis. The sugar is then converted to alcohol when grapes are made into wine. By looking at carbon atoms in the alcohol, the scientists worked out how much CO2 from fossil fuels was in the air when the plant grew.

Image: Gabor Izso/iStockphoto

But how did scientists tell the difference between natural CO2 emissions and CO2 from fossil fuels?
Some CO2 in the atmosphere contains a special type of carbon called carbon-14. Fossil fuels contain no carbon-14, so when they burn the CO2 released is free from carbon-14. This dilutes the amount of CO2 in the atmosphere that contains carbon-14.
The scientists measured the amount of carbon-14 in the bottles of wine. Small quantities indicated that the air the grapes grew in was high in CO2 from fossil fuels; larger amounts of carbon-14 meant there was less fossil fuel CO2 pollution.

Scientists used an accelerator mass spectrometer to find out how much carbon-14 the different wines contained.

Image: Centre for Isotope Research, University of Groningen

'The study shows very elegantly how our footprint of fossil fuel emissions over the last few decades lies dormant in natural products like wine.' Alastair Lewis, atmospheric science expert

Alastair Lewis, National Centre for Atmospheric Science.

Image: National Centre for Atmospheric Science

So will all climate-change scientists soon be hitting the bottle?
'Using wine isn't perfect. The CO2 record you are looking at is limited to the period when the plants take it up - during the day and between July and October.' Sanne Palstra
'Air sampling has big advantages so our wine method will never replace it - just supplement it. But sampling wine is a cheap and easy way of measuring atmospheric CO2 at many more sites around Europe.'