- Leave it to the French to measure global climate change
through the archives of 600 years of harvesting the pinot noir grape in
Burgundy. A group of French climatologists and ecologists has pored over
records squirrelled away in parish papers and obscure municipal files to
find which day the fabled grapes were picked in each year stretching back
to 1370.
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- That harvest date falls precisely at the moment the grapes
achieve perfect ripeness -- and therefore the most glorious taste -- and
is tightly controlled by temperature, said Isabelle Chuine, a scientist
at the Centre for Evolutionary and Functional Ecology in Montpellier, whose
paper on her findings was published today in the journal Nature.
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- In homage to the splendour of this grape, which was developed
in Burgundy many centuries ago, these dates have been reverently recorded
year after year since the Black Death stalked the French countryside in
the 14th century.
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- That means the harvest dates, worked backward through
complex mathematical models, can be used to figure out variations in temperature,
compared to the reference period of 1960 to 1989 -- and not just for a
few years, but in the longest uninterrupted line known in which the actual
dates are written down.
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- (The findings jibe with more complex global temperature
models such as those derived from tree rings and ice cores.)
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- The grape-harvest results surprised Dr. Chuine and the
other researchers. They expected to find that temperatures in the 1990s
were warmer than anything France had experienced in hundreds of years.
Climatologists have said that the 1990s showed that global climate change,
with its episodes of extreme weather, had set in.
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- Around the world, average temperatures rose through the
1990s, and catastrophic weather accompanied the trend: hurricanes, droughts,
heat waves, deluges and thousands of heat deaths throughout Europe.
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- But when the French scientists crunched their grape numbers,
they found that the land of the pinot noir had been about as warm as the
1990s in the 1380s, 1420s and 1520s, and then through the 1630s to the
1680s, only to cool off again.
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- Pascal Yiou, an applied mathematician at Gif-sur-Yvette,
just south of Paris, who also worked on the paper, said the pinot noir
figures are significant because they underline the fact that the warming
trend through the 20th century is unprecedented.
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- While individual decades or years have been warm in Burgundy,
the anomaly now is that the warming trend has kept going for more than
a century.
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- That is a strong sign of climate change, he said.
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- The big shock, though, was the evidence from the summer
of 2003, Dr. Chuine said.
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- In Burgundy, the temperature was far hotter in 2003 than
it had been since the medieval grape harvesters began collecting data,
the French researcher said.
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- The models showed that Burgundy was 5.86 degrees Celsius
warmer than during the reference period. The next-highest anomaly was in
1523, when it was 4.10 degrees above the norm. In temperature terms, a
difference of more than a degree is considered huge.
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- Worse still, said Dr. Yiou, is that the 2003 temperature
"was completely unpredictable from what we knew before 2003."
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- He said it could be a coincidence, or troubling evidence
that climate is becoming more variable and therefore more unstable.
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- But he also said that the French are jumping on the data
to figure out what they mean because 2003 was a catastrophic year for humans
in France.
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- That year, 10,000 French residents died of heat.
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- It was a strange year around the world. The World Meteorological
Organization called 2003 the third-warmest year around the world since
1861, when weather records began.
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- There were large wildfires in British Columbia, salmon
suffocated in lethally warm streams, and a fierce drought plagued the Prairies.
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- Dr. Chuine said she has little doubt that global climate
change was responsible for the strangeness of 2003.
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- © 2004 Bell Globemedia Publishing Inc. All Rights
Reserved.
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