How Does Climate Impact Wine?

One of the most frequently asked and difficult to answer questions about wine is seemingly straightforward: "Was this a good year or a bad year in California, France, Italy, Argentina, or anywhere else?"

Whether or not any particular vintage is good or bad or somewhere in between is a product of countless natural phenomena, most of them tied to the climate. These days, past assumptions about the climate in any particular place are no longer as reliable as they once were given the effects of climate change. It's become so dramatic that I recently wrote a book, Crushed: How a Changing Climate Is Altering the Way We Drink.

Climate is at the root, so to speak, of not just the character of any given vintage, but also of the nature of every wine region on the planet. Here's how it affects what ends up in your glass.

What Grapes Are Planted Where

Different grape varieties respond in unique ways to warm and cool climate conditions. Cabernet Sauvignon, for example, expresses itself far differently in the more maritime climate of Bordeaux than it does in the dry, sunny Napa Valley. The varieties in climate largely account for the typical overall character of Cab (or Merlot or Chardonnay or any other wine) from different regions. Terroir–soil type, underlying geology, and more–also play significant roles.

Climate also affects which grapes should be planted at all in any particular place. Riesling, for example, thrives in relatively cooler climates, where its acidity lends an almost electric sense of energy to the best wines. Hot-climate Riesling, on the other hand, tends to be flatter and lacking in the verve that its cooler-climate cousins possess. The impact temperature has on wine is challenging to overstate.

When the Grapes Are Picked

As grapes develop and ripen throughout the growing season, their sugars climb as their acids fall. Deciding when to harvest any particular vineyard or block of vines is generally based on when a perceived balance is struck between the energy of the acids and ripeness of the fruit. In hotter climates and vintages, ripeness tends to be achieved earlier than it is in cooler ones. Grapes in cooler regions often need more hang time (that is, time on the vine), developing sugars and reducing acidity, than their hot-climate counterparts do.

Unsurprisingly, climate change is affecting harvest times, too. Unusual heat spikes or the threat of wildfires are more frequently necessitating earlier picking in order to guarantee that there's usable fruit to work with. This puts more pressure on the winemaker and their team as they go about the process of selecting usable grapes, crushing them, fermenting the juice, and determining how to age it.

In response to this, some growers are experimenting with grape varieties that bud and ripen at different times from what they already have planted. This often allows them to mitigate the threat of spring frosts, hail, summertime heat spikes, and more. On top of this, growers around the world are also working with varieties that are more well-suited to the effects of climate change in their specific location. In practice, this often means planting varieties that are more heat-resistant and better able to withstand the conditions brought on by our changing climate.

Location, Location, Location

Catastrophic events like wildfires and smoke taint, torrential and extended rains just before harvest, and freak frost and freeze events are becoming more common with each passing year thanks to climate change. To paraphrase one wine professional I spoke with as I was researching my book, climate change isn't just about global warming, it's about global weirding. The climate is just plain weird these days, and doesn't show signs of correcting itself.

Yet barring extreme scenarios like those, the inherent nature of the climate in one particular region or appellation leaves its proverbial fingerprint on the wines that are grown there in predictable ways. Hotter climates tend to produce riper, more effusively fruit-driven wines, whereas cooler climates generally are home to more brisk, occasionally savory ones. Then again, there's more than climate that affects the nature of wine. In hotter regions, for example, vineyards planted at greater altitude can benefit from cooler conditions.

Your best bet, then, is not to ask about the nature of a particular vintage over an entire country or region, but to focus on a smaller appellation, look at the overall climate in general and how it manifested itself that year, and go from there. And remember: These days, past assumptions about climate are becoming increasingly more difficult to rely on.