The Gist
Cool climates retain more acid and produce less sugar (and so less alcohol); warm climates do the opposite. Mosel Riesling sits at one extreme — bracingly acidic and 8% alcohol — while Châteauneuf-du-Pape Grenache sits at the other, soft and 15%+. You can often place a wine on the climate map before you've identified the grape.
Mechanism
As grapes ripen, sugar accumulates and natural acid decreases — specifically malic acid is respired away in warm conditions. Cool climates: less acid respiration → higher retained acid + lower sugar at physiological ripeness → lower potential alcohol. Warm climates: more acid respiration → lower acid + more sugar → higher alcohol.
High acid + low alcohol = cool climate. Low acid + very high alcohol = warm climate. Mosel Riesling (7.5–10% alc, very high acid) → extreme cool climate. Grenache CdP (14.5–16% alc, very low acid) → extreme warm climate. The acid/alcohol ratio is often detectable before any aromatic identification is made.
Deeper mechanism
Torrontés is a useful case study: it is highly aromatic (suggesting warm climate by analogy with Gew/Viognier) but has medium-to-medium-high acid (Salta's high altitude moderates acid loss despite warm daytime temperatures). The disconnect between aromatic register and structural profile is the tell — no other aromatic white on the exam list has higher acid than Torrontés relative to its floral intensity.
Confusion analysis
Torrontés vs. Gewürztraminer
Both floral, both aromatic. Gew: very low acid, very high alcohol, full body. Torrontés: medium-plus acid, medium alcohol, lighter body. Structure directly contradicts the aromatic similarities. Read the acid first.
Related varietals
This concept comes up when tasting: Riesling, Grüner Veltliner, Gewürztraminer, Albariño, Torrontés, Grenache