Cool Climate, n.
Cool climate is the kind of phrase that spills from the mouths of sommeliers, winemakers, sales reps, and export managers often enough that it may risk falling from the class of 'semi-technical term' to the level of 'brandspeak'. Hopefully, this won't be the case, because the phrase describes an important effect of a wine's place of origin, and some of us are sort of in love with that effect, and don't want to see the words lose their sheen. For now, the phrase still moves us.
The phrase itself is simple, referring to an environment where average growing temperatures are relatively cool. Since most of us in the wine trade aren't actual scientists, we tend to use the term in place of more-precise but also more-cumbersome official classifiers, ones like Continental, Maritime-Temperate, or UC Davis' Region I. What 'cool climate' describes isn't extremely rigid (there aren't exact agreed-upon boundaries for temperature range or days in the warmer growing season to standardize what falls into the somewhat colloquial category), but its use is consistent and common enough to get the job done.
Cool climate means places like Burgundy, Willamette Valley, Loire Valley, certain parts of California's coast. Places where, during the growing and ripening seasons, the fruit doesn't see a whole ton of heat. Sure, there may be a few days in the 90s, but, for the most part, ripening happens in the 70s and 80s.
These mild temperatures matter because of two physiological processes at work in a ripening grape. The first is photosynthesis, and it is how the plant creates energy in the form of sugar, using sunlight. During ripening, virtually all new sugars go straight to the grape, making it sweeter as it hangs. This process happens faster in warmer temperatures, so grapes accumulate sugar at a higher rate. More sugar means more alcohol in the fully fermented wine (and often more fruit flavor, too).
The other process is called respiration, and it is how the plant burns certain acids for use as energy. Like photosynthesis, respiration is heat-sensitive, so grapes will lose acid more quickly when it is warm. Since the grape is also accumulating sugar as acidity falls, eyeballing the spot where the two are in balance—and then harvesting—is the first great trick of a skilled winemaker.
Since these two mechanisms work more slowly in a cool climate, wines from those areas tend to keep more acidity, have less alcohol, and present more subdued fruit flavors (which in turn means the wines can sometimes exhibit more mineral character). These personality traits usually add up to a very attractive, vivacious tension in a wine, and I know more than a few wine professionals who seem to have become committed, lifelong addicts to the effect, like this guy, these brothers, and Joe.