Using Hadley Centre climate model (HadCM3) output and an A2 emission scenario (Pope et al., 2000)
to 2049 for 27 of the world’s top wine producing regions, Jones et al. (2005a) compared the average climates of
two periods, 1950-1999 and 2000-2049. The results suggest that mean growing season temperatures will warm
by an average 1.3ºC over the wine regions studied with Burgundy (Beaujolais), Rhine Valley, Barolo, and
Bordeaux differences ranging from 0.9-1.4ºC (Figure 4). Also, the projected changes are greater for the
Northern Hemisphere (1.3ºC) than the Southern Hemisphere (0.9ºC). Examining the rate of change projected
for the 2000-2049 period only reveals significant changes in each wine region with trends ranging from 0.2ºC to
0.6ºC per decade. Overall trends during the 2000-2049 period average 2ºC across all regions with the smallest
warming in South Africa (0.9ºC/50 years) and greatest warming in Portugal (2.9ºC/50 years). For the Burgundy
(Beaujolais), Rhine Valley, Barolo, and Bordeaux regions, decadal trends are modeled at 0.3-0.5ºC while the
overall trends are predicted to be 1.5-2.4ºC (Figure 4). In addition, Jones et al. (2005a) showed that many of the
wine regions may be at or near their optimum growing season temperature for high quality wine production and
further increases, as predicted by the differences between the means of the 1950-1999 and 2000-2049 periods,
will place some regions outside their theoretical optimum growing season climate. The magnitude of these
mean growing season changes indicate potential shifts in climate maturity types for many regions at or near a
given threshold of ripening potential for varieties currently grown in that region. Referring back to Figure 1,
where Bordeaux’s growing season climate of the last 50 years averaged 16.5ºC and add to it the overall trend in
projected warming in Bordeaux of 2.3ºC by 2049. An 18.8ºC average growing season would place Bordeaux at
the upper end of the optimum ripening climates for many of the red varieties grown there today and outside the
ideal climates for the main white varieties grown. Still more evidence of these impacts come from Napa, where a
17.5ºC historical average is projected to warm by 2.2ºC to 19.7ºC by 2049. This would place Napa at the upper
end of optimal ripening climates for nearly all of the most common varieties (Figure 1). Finally, the results also
show warming during the dormant periods which could influence hardening potential for latent buds, but