Perhaps no word has caused more confusion in the world of wine in the last few decades than terroir, that nebulous combination of land, weather, and tradition. Many would hold that the goal of wine-making should be to allow the sense of place to shine through, to be true to the conditions that produced the grapes of a given vintage.
Indeed, much of what sommeliers and wine lovers prize in a wine is that very sense of place. Yet we should remember that it is a very fragile thing: decisions made at every step of the process will impact the resulting wine. That's why pieces like this in my hometown Seattle Times are somewhat misleading, there are simply too many variables.
Above: some of the most iconic terroir in the world, the main slope of Barbaresco
For one, saying that grapes come from the same vineyard and thus should taste the same when made into wine, there are so many unspoken assumptions. Even relatively small vineyards can have quite different soil types, slopes, exposures to the sun, and shelter (or lack thereof) from wind. Different winemakers can ask for different regimens of leaf-pulling, green-harvesting, and other vineyard management techniques. They can pick their grapes at different times, desiring different levels of sugar, acid, and phenolic ripeness.
Once harvested, there are nearly endless ways to sort, crush, ferment, press, age, and bottle wine. Each of those decisions affects the flavor further, potentially overwhelming the sense of terroir that we lust for. Simply selecting two wines from the same vineyard source and expecting them to taste the same is, well, naive.
That's not to say that terroir is meaningless: indeed, what's remarkable is that despite all those variables, often a sense of place does shine through in bottlings from the same site. It's one of the true miracles of wine, and something to be celebrated. It's not absolute or certain though, and treating it as such is an act of folly.